8/14/2019 Exploration Routing Semester 2
1/336
2007 Cisco Systems, Inc. All rights reserved. Cisco PublicITE PC v4.0Chapter 1 1
Introduction to Routingand Packet Forwarding
Routing Protocols andConcepts Chapter 1
8/14/2019 Exploration Routing Semester 2
2/336
ITE PC v4.0Chapter 1 2 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Objectives Identify a router as a computer with an OS and
hardware designed for the routing process.
Demonstrate the ability to configure devices andapply addresses.
Describe the structure of a routing table.
Describe how a router determines a path andswitches packets
8/14/2019 Exploration Routing Semester 2
3/336
ITE PC v4.0Chapter 1 3 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router as a Computer Describe the basic purpose of a router
-Computers that specialize in sending packets over the data
network. They are responsible for interconnecting networks byselecting the best path for a packet to travel and forwardingpackets to their destination
Routers are the network center
-Routers generally have 2 connections:
-WAN connection (Connection to ISP)
-LAN connection
8/14/2019 Exploration Routing Semester 2
4/336
ITE PC v4.0Chapter 1 4 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router as a Computer Data is sent in form of packets between 2 end devices
Routers are used to direct packet to its destination
(routing table)
8/14/2019 Exploration Routing Semester 2
5/336
ITE PC v4.0Chapter 1 5 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router as a Computer Routers examine a packets destination IP address and
determine the best path by enlisting the aid of a routing
table
8/14/2019 Exploration Routing Semester 2
6/336ITE PC v4.0Chapter 1 6 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router as a Computer Router components and their functions:
CPU - Executes operating system instructions
Random access memory (RAM) - Contains the running copy ofconfiguration file. Stores routing table. RAM contents lost when poweris off
Read-only memory (ROM) - Holds diagnostic software used whenrouter is powered up. Stores the routers bootstrap program.
Non-volatile RAM (NVRAM) - Stores startup configuration. This mayinclude IP addresses (Routing protocol, Hostname of router)
Flash memory - Contains the operating system (Cisco IOS)
Interfaces - There exist multiple physical interfaces that are used toconnect network. Examples of interface types:
-Ethernet / fast Ethernet interfaces
-Serial interfaces
-Management interfaces
8/14/2019 Exploration Routing Semester 2
7/336ITE PC v4.0Chapter 1 7 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router as a Computer Router components
8/14/2019 Exploration Routing Semester 2
8/336ITE PC v4.0Chapter 1 8 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router as a Computer Major phases to the
router boot-up process
Test router hardwarePower-On Self Test(POST)
Execute bootstrap loader
Locate & load Cisco IOSsoftware
-Locate IOS
-Load IOS
Locate & load startupconfiguration file or entersetup mode
-Bootstrap program looksfor configuration file
8/14/2019 Exploration Routing Semester 2
9/336ITE PC v4.0Chapter 1 9 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router as a Computer Verify the router boot-up process:
-The show version command is used to view information about
the router during the bootup process. Information includes:Platform model number
Image name & IOS version
Bootstrap version stored in ROMImage file name & where it was loaded from
Number & type of interfaces
Amount of NVRAMAmount of flash
Configuration register
8/14/2019 Exploration Routing Semester 2
10/336ITE PC v4.0Chapter 1 10 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router as a Computer
8/14/2019 Exploration Routing Semester 2
11/336ITE PC v4.0Chapter 1 11 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router as a Computer Router Interface is a physical connector that enables a
router to send or receive packets
Each interface connects to a separate network
Consist of socket or jack found on the outside of a router
Types of router interfaces:-Ethernet
-Fastethernet
-Serial-DSL
-ISDN
-Cable
8/14/2019 Exploration Routing Semester 2
12/336ITE PC v4.0Chapter 1 12 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router as a Computer Two major groups of Router InterfacesLAN Interfaces:
Are used to connect router to LANnetwork
Has a layer 2 MAC address
Can be assigned a Layer 3 IP
addressUsually consist of an RJ-45 jack
WAN Interfaces
Are used to connect routers to external networks thatinterconnect LANs.
Depending on the WAN technology, a layer 2 addressmay be used.
Uses a layer 3 IP address
8/14/2019 Exploration Routing Semester 2
13/336
ITE PC v4.0Chapter 1 13 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router as a Computer Routers and the Network Layer
Routers use destination IP address to forward packets
The path a packet takes is determined after a routerconsults information in the routing table.
After router determines the best path
Packet is encapsulated into a frame
Frame is then placed on network medium in form of Bits
8/14/2019 Exploration Routing Semester 2
14/336
ITE PC v4.0Chapter 1 14 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router as a Computer Routers Operate at Layers 1, 2 & 3
Router receives a stream of encoded bits
Bits are decoded and passed to layer 2Router de-encapsulates the frame
Remaining packet passed up to layer 3
-Routing decision made at this layer by examiningdestination IP address
Packet is then re-encapsulated & sent out outbound interface
8/14/2019 Exploration Routing Semester 2
15/336
ITE PC v4.0Chapter 1 15 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Configure Devices and Apply Addresses Implementing Basic Addressing Schemes
When designing a new network or mapping an existing
network you must provide the following information inthe form of a document:
-Topology drawing that Illustrates physical connectivity
Address table that provides the following information:
Device name
Interfaces used
IP addresses
Default gateway
Ex. 1.2.1.1
8/14/2019 Exploration Routing Semester 2
16/336
ITE PC v4.0Chapter 1 16 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Configure Devices and Apply Addresses Basic Router Configuration
A basic router configuration should contain the following:
-Router name - Host name should be unique-Banner - At a minimum, banner should warn againstunauthorized use
-Passwords - Use strong passwords
-Interface configurations - Specify interface type, IP addressand subnet mask. Describe purpose of interface. Issue noshutdown command. If DCE serial interface issue clock ratecommand.
After entering in the basic configuration the following tasks shouldbe completed
-Verify basic configuration and router operations.
-Save the changes on a router
8/14/2019 Exploration Routing Semester 2
17/336
ITE PC v4.0Chapter 1 17 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Configure Devices and Apply Addresses
8/14/2019 Exploration Routing Semester 2
18/336
ITE PC v4.0Chapter 1 18 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Configure Devices and Apply Addresses Verify Basic Router Configuration
-Issue the show running-configcommand
-Save the basic router configuration by Issuing the copyrunning-config startup-configcommand
-Additional commands that will enable you to further verifyrouter configuration are:
Show running-config - Displays configuration currently inRAM
Show startup-config - Displays configuration file NVRAM
Show IP route - Displays routing table
Show interfaces - Displays all interface configurations
Show IP int brief - Displays abbreviated interface
configuration information
8/14/2019 Exploration Routing Semester 2
19/336
ITE PC v4.0Chapter 1 19 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table Structure Routing Table is stored in ram and contains information
about:
Directly connected networks - this occurs when a device is
connected to another router interface
Remotely connected networks - this is a network that is notdirectly connected to a particular router
Detailed information about the networks include source ofinformation, network address & subnet mask, and Ip address ofnext-hop router
Show ip route command is used to view a routing table
8/14/2019 Exploration Routing Semester 2
20/336
ITE PC v4.0Chapter 1 20 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table Structure
Adding a connected network to the routing table-Router interfaces
Each router interface is a member of a different network
Activated using the no shutdowncommand
In order for static and dynamic routes to exist in routingtable you must have directly connected networks
8/14/2019 Exploration Routing Semester 2
21/336
ITE PC v4.0Chapter 1 21 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table Structure Static routes in the routing table
-Includes: network address and subnet mask and IP address of
next hop router or exit interface-Denoted with the code S in the routing table
-Routing tables must contain directly connected networks usedto connect remote networks before static or dynamic routing
can be used
When to use static routes
-When network only consists of a few routers
-Network is connected to internet only through one ISP
-Hub & spoke topology is used on a large network
8/14/2019 Exploration Routing Semester 2
22/336
ITE PC v4.0Chapter 1 22 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table Structure Connected and Static routes
8/14/2019 Exploration Routing Semester 2
23/336
ITE PC v4.0Chapter 1 23 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table Structure Dynamic routing protocols
-Used to add remote networks to a routing table
-Are used to discover networks-Are used to update and maintain routing tables
Automatic network discovery
-Routers are able discover new networks by sharing routingtable information
8/14/2019 Exploration Routing Semester 2
24/336
ITE PC v4.0Chapter 1 24 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table Structure Maintaining routing tables
-Dynamic routing protocols are used to share routing information withother router & to maintain and up date their own routing table.
IP routing protocols. Example of routing protocols include:
-RIP
-IGRP
-EIGRP
-OSPF
-IS-IS
-BGP
8/14/2019 Exploration Routing Semester 2
25/336
ITE PC v4.0Chapter 1 25 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table Structure Routing Table Principles
-3 principles regarding routing tables:
Every router makes its decisions alone, based on theinformation it has in its routing table.
Different routing table may contain different information
A routing table can tell how to get to a destination but nothow to get back
8/14/2019 Exploration Routing Semester 2
26/336
ITE PC v4.0Chapter 1 26 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table Structure Effects of the 3 Routing Table Principles
-Packets are forwarded through the network from one router
to another, on a hop by hop basis.-Packets can take path X to a destination but return viapath Y (Asymmetric routing).
8/14/2019 Exploration Routing Semester 2
27/336
ITE PC v4.0Chapter 1 27 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router Paths and Packet Switching Internet Protocol (IP) packet format contains fields that
provide information about the packet and the sending
and receiving hosts Fields that are important for CCNA students:
-Destination IP address
-Source IP address-Version & TTL
-IP header length
-Precedence & type of service-Packet length
8/14/2019 Exploration Routing Semester 2
28/336
8/14/2019 Exploration Routing Semester 2
29/336
ITE PC v4.0Chapter 1 29 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router Paths and Packet Switching A Metric is a numerical value used by routing protocols helpdetermine the best path to a destination
The smaller the metric value the better the path
2 types of metrics used by routing protocols are:-Hop count - this is the number of routers a packet must travelthrough to get to its destination
-Bandwidth - this is the speed of a link also known as the data
capacity of a link
8/14/2019 Exploration Routing Semester 2
30/336
8/14/2019 Exploration Routing Semester 2
31/336
ITE PC v4.0Chapter 1 31 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router Paths and Packet Switching Path determination is a process used by a router to pick the best
path to a destination
One of 3 path determinations results from searching for the best
pathDirectly connected network
Remote network
No route determined->ICMP unreachable
8/14/2019 Exploration Routing Semester 2
32/336
ITE PC v4.0Chapter 1 32 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router Paths and Packet Switching Switching Function of Router is the process used by a
router to switch a packet from an incoming interface to
an outgoing interface on the same router.-A packet received by a router will do the following:
Strips off layer 2 headers.
Examines destination IP address located in Layer 3header to find best route to destination.
Re-encapsulates layer 3 packet into layer 2 frame.
Forwards frame out exit interface.
8/14/2019 Exploration Routing Semester 2
33/336
ITE PC v4.0Chapter 1 33 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router Paths and Packet Switching As a packet travels from one networking device to another
-The Source and Destination IP addresses NEVER change
-The Source & Destination MAC addresses CHANGE as packetis forwarded from one router to the next.
-TTL field decrement by one until a value of zero is reached atwhich point router discards packet (prevents packets from
endlessly traversing the network)
8/14/2019 Exploration Routing Semester 2
34/336
ITE PC v4.0Chapter 1 34 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router Paths and Packet Switching Path determination and switching function details. PC1
Wants to send something to PC 2 here is part of what
happensStep 1 - PC1 encapsulates packet into a frame. Framecontains R1s destination MAC address
8/14/2019 Exploration Routing Semester 2
35/336
ITE PC v4.0Chapter 1 35 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router Paths and Packet Switching
Step 2 - R1 receives Ethernet frame.
R1 sees that destination MAC address matches its ownMAC.
R1 then strips off Ethernet frame.
R1 Examines destination IP.
R1 consults routing table looking for destination IP.
After finding destination IP in routing table, R1 now looks upnext hop IP address.
R1 re-encapsulates IP packet with a new Ethernet frame.
R1 forwards Ethernet packet out Fa0/1 interface.
8/14/2019 Exploration Routing Semester 2
36/336
8/14/2019 Exploration Routing Semester 2
37/336
ITE PC v4.0Chapter 1 37 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router Paths and Packet Switching Path determination and switching function details. PC1 Wants to
send something to PC 2 here is part of what happens
Step 3 - Packet arrives at R2
R2 receives Ethernet frame
R2 sees that destination MAC address matches its ownMAC
R2 then strips off Ethernet frame
R2 Examines destination IP
R2 consults routing table looking for destination IPAfter finding destination IP in routing table, R2 now looks upnext hop IP address
R2 re-encapsulates IP packet with a new data link frame
R2 forwards Ethernet packet out S0/0 interface
8/14/2019 Exploration Routing Semester 2
38/336
ITE PC v4.0Chapter 1 38 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router Paths and Packet Switching
Path determination and switching function details. PC1 Wants tosend something to PC 2 here is part of what happens
Step 4 - Packet arrives at R3
R3 receives PPP frame
R3 then strips off PPP frameR3 Examines destination IP
R3 consults routing table looking for destination IP
After finding destination IP in routing table, R3 is directly
connected to destination via its fast Ethernet interfaceR3 re-encapsulates IP packet with a new Ethernet frame
R3 forwards Ethernet packet out Fa0/0 interface
Step 5 - IP packet arrives at PC2. Frame is decapsulated &
processed by upper layer protocols.
8/14/2019 Exploration Routing Semester 2
39/336
ITE PC v4.0Chapter 1 39 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Summary
Routers are computers that specialize in sending data over a network.
Routers are composed of:
-Hardware i.e. CPU, Memory, System bus, Interfaces
-Software used to direct the routing processIOS
Configuration file
Routers need to be configured. Basic configuration consists of:-Router name
-Router banner
-Password(s)
-Interface configurations i.e. IP address and subnet mask Routing tables contain the following information
-Directly connected networks
-Remotely connected networks-Network addresses and subnet masks
-IP address of next hop address
8/14/2019 Exploration Routing Semester 2
40/336
ITE PC v4.0Chapter 1 40 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Summary Routers determine a packets path to its destination bydoing the following
Receiving an encapsulated frame & examining destinationMAC address.
If the MAC address matches then Frame is de-encapsulatedso that router can examine the destination IP address.
If destination IP address is in routing table or there is a staticroute then Router determines next hop IP address. Router willre-encapsulate packet with appropriate layer 2 frame and sendit out to next destination.
Process continues until packet reaches destination.
Note - only the MAC addresses will change the source anddestination IP addresses do not change.
8/14/2019 Exploration Routing Semester 2
41/336
ITE PC v4.0Chapter 1 41 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
8/14/2019 Exploration Routing Semester 2
42/336
2007 Cisco Systems, Inc. All rights reserved. Cisco PublicITE PC v4.0Chapter 1 1
Static Routing
Routing Protocols andConcepts Chapter 2
8/14/2019 Exploration Routing Semester 2
43/336
ITE PC v4.0Chapter 1 2 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Objectives Define the general role a router plays in networks.
Describe the directly connected networks, different
router interfaces
Examine directly connected networks in the routingtable and use the CDP protocol
Describe static routes with exit interfaces
Describe summary and default route
Examine how packets get forwarded when usingstatic routes
Identify how to manage and troubleshoot static routes
8/14/2019 Exploration Routing Semester 2
44/336
ITE PC v4.0Chapter 1 3 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
General Role of the Router Functions of a Router
-Best Path Selections
-Forwarding packets to destination
Introducing the Topology
-3 x 1800 series routers connected via WAN links
-Each router connected to a LAN represented by a switch and aPC
8/14/2019 Exploration Routing Semester 2
45/336
8/14/2019 Exploration Routing Semester 2
46/336
ITE PC v4.0Chapter 1 5 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Interfaces Examining Router Interfaces
-Show IP router command used to view routing table
-Show Interfaces command used to show status of aninterface
-Show IP Interface brief command used to show a portion ofthe interface information
-Show running-config command used to show configurationfile in RAM
8/14/2019 Exploration Routing Semester 2
47/336
ITE PC v4.0Chapter 1 6 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Interfaces Configuring an Ethernet interface
-By default all serial and Ethernet interfaces are down
-To enable an interface use the No Shutdown command
8/14/2019 Exploration Routing Semester 2
48/336
8/14/2019 Exploration Routing Semester 2
49/336
ITE PC v4.0Chapter 1 8 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Interfaces Configuring a Serial interface
-Enter interface configuration mode
-Enter in the ip address and subnet mask
-Enter in the no shutdown command
Example:
-R1(config)#interface serial 0/0
-R1(config-if)#ip address 172.16.2.1 255.255.255.0
-R1(config-if)#no shutdown
8/14/2019 Exploration Routing Semester 2
50/336
ITE PC v4.0Chapter 1 9 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Interfaces Examining Router Interfaces
-Physically connecting a WAN Interface.
-A WAN Physical Layer connection has sides:Data Circuit-terminating Equipment (DCE) This is theservice provider. CSU/DSU is a DCE device.
Data Terminal Equipment (DTE) Typically the router is theDTE device.
8/14/2019 Exploration Routing Semester 2
51/336
ITE PC v4.0Chapter 1 10 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Interfaces Configuring serial links in a lab environment
One side of a serial connection must be considered a DCE
This requires placing a clocking signal use the clock rate
command.
Example:
-R1(config)#interface serial 0/0
-R1(config-if)#clockrate 64000
Serial Interfaces require a clock signal to control the timing ofthe communcations.
8/14/2019 Exploration Routing Semester 2
52/336
ITE PC v4.0Chapter 1 11 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table and CDP Protocol Purpose of the debug ip routing command
Allows you to view changes that the router performs whenadding or removing routes
Example:
-R2#debug ip routing
-IP routing debugging is on
8/14/2019 Exploration Routing Semester 2
53/336
ITE PC v4.0Chapter 1 12 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table and CDP Protocol To configure an Ethernet interface
Example:
-R2(config)#interface fastethernet 0/0-R2(config-if)#ip address 172.16.1.1 255.255.255.0
-R2(config-if)#no shutdown
8/14/2019 Exploration Routing Semester 2
54/336
ITE PC v4.0Chapter 1 13 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table and CDP Protocol When a router only has its interfaces configured & no
other routing protocols are configured then:
-The routing table contains only the directly connected networks-Only devices on the directly connected networks are reachable
8/14/2019 Exploration Routing Semester 2
55/336
ITE PC v4.0Chapter 1 14 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table and CDP Protocol
8/14/2019 Exploration Routing Semester 2
56/336
8/14/2019 Exploration Routing Semester 2
57/336
ITE PC v4.0Chapter 1 16 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table and CDP Protocol Purpose of CDP
A layer 2 cisco proprietary tool used to gather information aboutother directly connected Cisco devices.
Concept of neighbors
-2 types of neighbors
Layer 3 neighborsLayer 2 neighbors
8/14/2019 Exploration Routing Semester 2
58/336
ITE PC v4.0Chapter 1 17 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table and CDP Protocol CDP show commands
Show cdp neighbors command
-Displays the following information:Neighbor device ID
Local interface
Holdtime value, in secondsNeighbor device capability code
Neighbor hardware platform
Neighbor remote port IDShow cdp neighbors detail command
-Useful in determining if an IP address configuration error
8/14/2019 Exploration Routing Semester 2
59/336
ITE PC v4.0Chapter 1 18 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table and CDP Protocol
Disabling CDP
To disable CDP globally usethe following command
Router(config)#no cdp run
8/14/2019 Exploration Routing Semester 2
60/336
ITE PC v4.0Chapter 1 19 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes with Exit Interfaces Purpose of a static route
A manually configured route used when routing from a networkto a stub network (a network accessed by a single route)
8/14/2019 Exploration Routing Semester 2
61/336
ITE PC v4.0Chapter 1 20 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes with Exit Interfaces IP route command
To configure a static route use the following command: ip route
Example:-Router(config)# ip route network-address subnet-mask {ip-address | exit-interface }
8/14/2019 Exploration Routing Semester 2
62/336
ITE PC v4.0Chapter 1 21 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes with Exit Interfaces Dissecting static route syntax
ip route - Static route command
172.16.1.0 Destination network address255.255.255.0 - Subnet mask of destination network
172.16.2.2 - Serial 0/0/0 interface IP address on R2, which isthe "next-hop" to this network
8/14/2019 Exploration Routing Semester 2
63/336
ITE PC v4.0Chapter 1 22 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes with Exit Interfaces Configuring routes to 2 or more remote networks
Use the following commands for R1
-R1(config)#ip route 192.168.1.0 255.255.255.0 172.16.2.2-R1(config)#ip route 192.168.2.0 255.255.255.0 172.16.2.2
8/14/2019 Exploration Routing Semester 2
64/336
ITE PC v4.0Chapter 1 23 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes with Exit Interfaces Zinins 3 routing principles
Principle 1: "Every router makes its decision alone, based onthe information it has in its own routing table.
Principle 2: "The fact that one router has certain information inits routing table does not mean that other routers have the sameinformation.
Principle 3: "Routing information about a path from onenetwork to another does not provide routing information aboutthe reverse, or return path."
8/14/2019 Exploration Routing Semester 2
65/336
ITE PC v4.0Chapter 1 24 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes with Exit Interfaces Using Zinins 3 routing principles, how would you
answer the following?
-Would packets from PC1 reach their destination?Yes, packets destined for 172.16.1.0/24 and 192.168.1.0/24
networks would reach their destination.
-Does this mean that any packets from these networks destined
for 172.16.3.0/24 network will reach their destination?
No, because neither R2 nor R3 router has a route to the172.16.3.0/24 network.
8/14/2019 Exploration Routing Semester 2
66/336
ITE PC v4.0Chapter 1 25 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes with Exit Interfaces Resolving to an Exit Interface
-Recursive route lookup - Occurs when the router has to perform multiplelookups in the routing table before forwarding a packet. A static route that
forwards all packets to the next-hop IP address goes through the followingprocess (reclusive route lookup)
The router first must match static routes destination IP address with theNext hop address
The next hop address is then matched to an exit interface
8/14/2019 Exploration Routing Semester 2
67/336
ITE PC v4.0Chapter 1 26 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes with Exit Interfaces Configuring a Static route with an Exit Interface
-Static routes configured with an exit interface are more efficient
The routing table can resolve the exit interface in a single search insteadof 2 searches
-Example of syntax require to configure a static route with an exit interface
8/14/2019 Exploration Routing Semester 2
68/336
ITE PC v4.0Chapter 1 27 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes with Exit Interfaces Modifying Static routes
Existing static routes cannot be modified. The old static routemust be deleted by placing no in front of the ip route
Example:
-no ip route 192.168.2.0 255.255.255.0 172.16.2.2
A new static route must be rewritten in the configuration
8/14/2019 Exploration Routing Semester 2
69/336
ITE PC v4.0Chapter 1 28 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes with Exit Interfaces Verifying the Static Route Configuration
-Use the following commands
Step 1 show running-configStep 2 verify if static route has been entered correctly
Step 3 show ip route
Step 4 verify if route was configured in routing tableStep 5 issue ping command to verify packets can reachdestination and that Return path is working
8/14/2019 Exploration Routing Semester 2
70/336
ITE PC v4.0Chapter 1 29 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes with Exit Interfaces
Ethernet interfaces and ARP.If a static route is configured on an Ethernet link
-If the packet is sent to the next-hop router then
the destination MAC address will be theaddress of the next hops Ethernet interface
This is found by the router consulting the
ARP table.
If an entry isnt found then an ARPrequest will be sent out
8/14/2019 Exploration Routing Semester 2
71/336
8/14/2019 Exploration Routing Semester 2
72/336
ITE PC v4.0Chapter 1 31 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Summary and Default Route Configuring a summary route
Step 1: Delete the current static route
Step 2: Configure the summary static routeStep 3: Verify the new static route
8/14/2019 Exploration Routing Semester 2
73/336
8/14/2019 Exploration Routing Semester 2
74/336
ITE PC v4.0Chapter 1 33 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Summary and Default Route Static routes and subnet masks
The routing table lookup process will use the most specificmatch when comparing destination IP address and subnetmask
Default static routes and subnet masks
Since the subnet mask used on a default static route is 0.0.0.0all packets will match.
8/14/2019 Exploration Routing Semester 2
75/336
ITE PC v4.0Chapter 1 34 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes and Packet Forwarding
Packet forwarding withstatic routes. (recallZinins 3 routingprinciples)
Router 1
Packet arrives on R1sFastethernet 0/0interface
-R1 does not have a
route to the destinationnetwork,192.168.2.0/24
-R1 uses the default
static route.
8/14/2019 Exploration Routing Semester 2
76/336
ITE PC v4.0Chapter 1 35 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes and Packet Forwarding
Packet forwarding with static routes. (recall Zinins 3routing principles)
Router 2
-The packet arrives on the Serial 0/0/0 interface on R2.-R2 has a static route to 192.168.2.0/24 out Serial0/0/1.
8/14/2019 Exploration Routing Semester 2
77/336
ITE PC v4.0Chapter 1 36 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes and Packet Forwarding Packet forwarding with static routes. (recall Zinins 3
routing principles)
Router 3-The packet arrives on the Serial0/0/1 interface on R3.
-R3 has a connected route to 192.168.2.0/24 out Fastethernet
0/1.
8/14/2019 Exploration Routing Semester 2
78/336
ITE PC v4.0Chapter 1 37 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes and Packet Forwarding Troubleshooting a Missing Route
Tools that can be used to isolate routing problems
include:-Ping tests end to end connectivity
-Traceroute used to discover all of the hops (routers) along the
path between 2 points-Show IP route used to display routing table & ascertainforwarding process
-Show ip interface brief- used to show status of router interfaces
-Show cdp neighbors detail used to gather configurationinformation about directly connected neighbors
8/14/2019 Exploration Routing Semester 2
79/336
ITE PC v4.0Chapter 1 38 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes and Packet Forwarding Solving a Missing Route
Finding a missing or mis-configured route requires
methodically using the correct tools-Start with PING. If ping fails then use traceroute to determinewhere packets are failing to arrive
Issue: show ip route to examine routing table.-If there is a problem with a mis-configured static route removethe static route then reconfigure the new static route
8/14/2019 Exploration Routing Semester 2
80/336
ITE PC v4.0Chapter 1 39 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes and Packet Forwarding Solving a Missing Route
8/14/2019 Exploration Routing Semester 2
81/336
ITE PC v4.0Chapter 1 40 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routes and Packet Forwarding Solving a Missing Route
8/14/2019 Exploration Routing Semester 2
82/336
S
8/14/2019 Exploration Routing Semester 2
83/336
ITE PC v4.0Chapter 1 42 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Summary Static Routes
-This is a manually configured path that specifies how the routerwill get to a certain point using a certain path.
Summary static routes
-This is several static routes that have been condensed into asingle static route.
Default route
-It is the route packets use if there is no other possible match for
their destination in the routing table. Forwarding of packets when static route is used
-Zinins 3 routing principles describe how packets are forwarded
Troubleshooting static routes may require some of the following
commands:-Ping
-Traceroute
-Show IP route
-Show ip interface brief-Show cdp neighbors detail
8/14/2019 Exploration Routing Semester 2
84/336
8/14/2019 Exploration Routing Semester 2
85/336
2007 Cisco Systems, Inc. All rights reserved. Cisco PublicITE PC v4.0Chapter 1 1
Introduction to DynamicRouting Protocol
Routing Protocols andConcepts Chapter 3
8/14/2019 Exploration Routing Semester 2
86/336
ITE PC v4.0Chapter 1 2 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Objectives Describe the role of dynamic routing protocols and
place these protocols in the context of modernnetwork design.
Identify several ways to classify routing protocols.
Describe how metrics are used by routing protocols
and identify the metric types used by dynamic routingprotocols.
Determine the administrative distance of a route and
describe its importance in the routing process.
Identify the different elements of the routing table.
8/14/2019 Exploration Routing Semester 2
87/336
ITE PC v4.0Chapter 1 3 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Dynamic Routing Protocols - History
8/14/2019 Exploration Routing Semester 2
88/336
ITE PC v4.0Chapter 1 4 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Dynamic Routing Protocols Function(s) of Dynamic Routing Protocols:-Dynamically share information between routers.
-Automatically update routing table when topology changes.-Determine best path to a destination.
8/14/2019 Exploration Routing Semester 2
89/336
8/14/2019 Exploration Routing Semester 2
90/336
8/14/2019 Exploration Routing Semester 2
91/336
ITE PC v4.0Chapter 1 7 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static Routing Protocols Advantages of static routing-It can backup multiple interfaces/networks on a router
-Easy to configure-No extra resources are needed
-More secure
Disadvantages of static routing-Network changes require manual reconfiguration
-Does not scale well in large topologies
8/14/2019 Exploration Routing Semester 2
92/336
ITE PC v4.0Chapter 1 8 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static vs Dynamic Routing Protocols
8/14/2019 Exploration Routing Semester 2
93/336
ITE PC v4.0Chapter 1 9 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classifying Routing Protocols Dynamic routing protocols are grouped accordingto characteristics. Examples include:
-RIP-IGRP
-EIGRP
-OSPF
-IS-IS
-BGP
Autonomous System is a group of routers under
the control of a single authority.
8/14/2019 Exploration Routing Semester 2
94/336
ITE PC v4.0Chapter 1 10 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classifying Routing Protocols Types of routing protocols:-Interior Gateway Protocols (IGP)
-Exterior Gateway Protocols (EGP)
8/14/2019 Exploration Routing Semester 2
95/336
ITE PC v4.0Chapter 1 11 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classifying Routing Protocols Interior Gateway Routing Protocols (IGP)-Used for routing inside an autonomous system & used to routewithin the individual networks themselves.
-Examples: RIP, EIGRP, OSPF
Exterior Routing Protocols (EGP)
-Used for routing between autonomous systems-Example: BGPv4
Classifying Routing Protocols
8/14/2019 Exploration Routing Semester 2
96/336
ITE PC v4.0Chapter 1 12 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classifying Routing Protocols
IGP: Comparison of Distance Vector & Link StateRouting Protocols
Distance vector
routes are advertised as vectors
of distance & direction.
incomplete view of network
topology.
Generally, periodic
updates.
Link state
complete view of networktopology is created.
updates are not
periodic.
8/14/2019 Exploration Routing Semester 2
97/336
ITE PC v4.0Chapter 1 13 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classifying Routing Protocols Classful routing
protocols
Do NOT send subnet maskin routing updates
Classless routingprotocols
Do send subnet mask in
routing updates.
8/14/2019 Exploration Routing Semester 2
98/336
ITE PC v4.0Chapter 1 14 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classifying Routing Protocols Convergence is defined as when all routers routingtables are at a state of consistency
8/14/2019 Exploration Routing Semester 2
99/336
8/14/2019 Exploration Routing Semester 2
100/336
ITE PC v4.0Chapter 1 16 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Protocols Metrics Metrics used in IP routing protocols-Bandwidth
-Cost-Delay
-Hop count
-Load
-Reliability
Routing Protocols Metrics
8/14/2019 Exploration Routing Semester 2
101/336
ITE PC v4.0Chapter 1 17 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Protocols Metrics
The Metric Field in theRouting Table
Metric used for each
routing protocol-RIP - hop count
-IGRP & EIGRP -
Bandwidth (used bydefault), Delay (used bydefault), Load, Reliability
-IS-IS & OSPFCost,
Bandwidth (Ciscosimplementation)
8/14/2019 Exploration Routing Semester 2
102/336
ITE PC v4.0Chapter 1 18 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Protocols Metrics Load balancingThis is the ability of a router to distribute packets amongmultiple same cost paths
8/14/2019 Exploration Routing Semester 2
103/336
ITE PC v4.0Chapter 1 19 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Administrative Distance of a Route Purpose of a metricIts a calculated value used to determine the best path to adestination
Purpose of Administrative Distance
Its a numeric value that specifies the preference of a particularroute
8/14/2019 Exploration Routing Semester 2
104/336
ITE PC v4.0Chapter 1 20 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Administrative Distance of a Route Identifying the Administrative Distance (AD) in arouting table
It is the first number in the brackets in the routing table
8/14/2019 Exploration Routing Semester 2
105/336
ITE PC v4.0Chapter 1 21 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Administrative Distance of a Route Dynamic Routing Protocols
8/14/2019 Exploration Routing Semester 2
106/336
ITE PC v4.0Chapter 1 22 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Administrative Distance of a Route Directly connected routesHave a default AD of 0
Static RoutesAdministrative distance of a static route has a default value of1
8/14/2019 Exploration Routing Semester 2
107/336
Summary
8/14/2019 Exploration Routing Semester 2
108/336
ITE PC v4.0Chapter 1 24 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Summary
Dynamic routing protocols fulfill the following functions-Dynamically share information between routers
-Automatically update routing table when topology changes
-Determine best path to a destination Routing protocols are grouped as either
-Interior gateway protocols (IGP)Or
-Exterior gateway protocols(EGP)
Types of IGPs include
-Classless routing protocols - these protocols include subnet maskin routing updates
-Classful routing protocols - these protocols do not include subnetmask in routing update
Summary
8/14/2019 Exploration Routing Semester 2
109/336
ITE PC v4.0Chapter 1 25 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Summary
Metrics are used by dynamic routing protocols to calculate thebest path to a destination.
Administrative distance is an integer value that is used to
indicate a routers trustworthiness Components of a routing table include:
-Route source
-Administrative distance-Metric
Excercise 3.5.1
8/14/2019 Exploration Routing Semester 2
110/336
ITE PC v4.0Chapter 1 26 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
8/14/2019 Exploration Routing Semester 2
111/336
2007 Cisco Systems, Inc. All rights reserved. Cisco PublicITE PC v4.0Chapter 1 1
Distance Vector RoutingProtocols
Routing Protocols and Concepts Chapter 4
8/14/2019 Exploration Routing Semester 2
112/336
8/14/2019 Exploration Routing Semester 2
113/336
ITE PC v4.0Chapter 1 3 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Static routes VS scalability
8/14/2019 Exploration Routing Semester 2
114/336
8/14/2019 Exploration Routing Semester 2
115/336
ITE PC v4.0Chapter 1 5 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Distance Vector Routing Protocols Distance Vector TechnologyThe Meaning of Distance Vector:
A router using distance vector routing protocols knows 2things:
Distance to final destination
Vector, or direction, traffic should be directed
Distance Vector Routing Protocols
8/14/2019 Exploration Routing Semester 2
116/336
ITE PC v4.0Chapter 1 6 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Distance Vector Routing Protocols
Characteristics of Distance Vector routing protocols:
Periodic updates
Neighbors
Broadcast updates
Entire routing table is included with routing update
Distance Vector Routing Protocols
8/14/2019 Exploration Routing Semester 2
117/336
ITE PC v4.0Chapter 1 7 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Distance Vector Routing Protocols
Routing Protocol Algorithm:
-Defined as a procedure for accomplishing a certain task
8/14/2019 Exploration Routing Semester 2
118/336
ITE PC v4.0Chapter 1 8 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Distance Vector Routing ProtocolsRouting Protocol CharacteristicsCriteria used to compare routing protocols includes
Time to convergenceScalability
Classless or VLSMResource usage
Implementation & maintenance
8/14/2019 Exploration Routing Semester 2
119/336
ITE PC v4.0Chapter 1 9 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Distance Vector Routing Protocols
8/14/2019 Exploration Routing Semester 2
120/336
ITE PC v4.0Chapter 1 10 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Network Discovery Router initial start up (Cold Starts)
-Initial network discovery
Directly connected networks are initially placed inrouting table
Network Discovery
8/14/2019 Exploration Routing Semester 2
121/336
ITE PC v4.0Chapter 1 11 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Network Discovery Initial Exchange of Routing Information
If a routing protocol is configured then
-Routers will exchange routing information Routing updates received from other routers
-Router checks update for new information
If there is new information:
-Metric is updated
-New information is
stored in routing table
Network Discovery
8/14/2019 Exploration Routing Semester 2
122/336
ITE PC v4.0Chapter 1 12 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
y
Exchange of Routing InformationRouter convergence is reached when
-All routing tables in the network contain the samenetwork information
Routers continue to exchange routing information
-If no new information is found then Convergence isreached
8/14/2019 Exploration Routing Semester 2
123/336
8/14/2019 Exploration Routing Semester 2
124/336
ITE PC v4.0Chapter 1 14 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table Maintenance Periodic Updates: RIPv1 & RIPv2
These are time intervals in which a router sends
out its entire routing table.
8/14/2019 Exploration Routing Semester 2
125/336
8/14/2019 Exploration Routing Semester 2
126/336
ITE PC v4.0Chapter 1 16 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Table Maintenance Bounded Updates: EIGRP
EIRPG routing updates are
-Partial updates
-Triggered by topology changes
-Bounded
-Non periodic
Routing Table Maintenance
8/14/2019 Exploration Routing Semester 2
127/336
ITE PC v4.0Chapter 1 17 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
g
Triggered Updates
Conditions in which triggered updates are sent
-Interface changes state
-Route becomes unreachable
-Route is placed in routing table
Routing Table Maintenance
8/14/2019 Exploration Routing Semester 2
128/336
ITE PC v4.0Chapter 1 18 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
g
Random Jitter
Synchronized updates
A condition where multiple routers on multi access LAN
segments transmit routing updates at the same time.
Problems with synchronized updates
-Bandwidth consumption
-Packet collisionsSolution to problems with
synchronized updates
- Used of random variablecalled RIP_JITTER 0-25% of
default interval
Routing Loops
8/14/2019 Exploration Routing Semester 2
129/336
ITE PC v4.0Chapter 1 19 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Loops
Routing loops are
A condition inwhich a packet iscontinuouslytransmitted within
a series of routerswithout everreaching its
destination.
8/14/2019 Exploration Routing Semester 2
130/336
ITE PC v4.0Chapter 1 20 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Loops Routing loops may be caused by:
-Incorrectly configured static routes
-Incorrectly configured route redistribution
-Slow convergence
-Incorrectly configured discard routes
Routing loops can create the following issues
-Excess use of bandwidth
-CPU resources may be strained
-Network convergence is degraded
-Routing updates may be lost or not processed in a timelymanner
8/14/2019 Exploration Routing Semester 2
131/336
ITE PC v4.0Chapter 1 21 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Loops
Count to Infinity
This is a routing loop whereby packets bounceinfinitely around a network.
8/14/2019 Exploration Routing Semester 2
132/336
ITE PC v4.0Chapter 1 22 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Loops Setting a maximum (RIP = 15)
Distance Vector routing protocols set a specified
metric value to indicate infinity
Once a router counts to infinity it marks the routeas unreachable
Routing Loops
8/14/2019 Exploration Routing Semester 2
133/336
ITE PC v4.0Chapter 1 23 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
g p
Preventing loops with holddown timers
-Holddown timers allow a router to not accept any changes to aroute for a specified period of time.
-Point of using holddown timersAllows routing updates to propagate through network withthe most current information.
Routing Loops
8/14/2019 Exploration Routing Semester 2
134/336
ITE PC v4.0Chapter 1 24 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
g p
The Split Horizon Rule is used to prevent routingloops
Split Horizon rule:
A router should not advertise a network through theinterface from which the update came.
8/14/2019 Exploration Routing Semester 2
135/336
ITE PC v4.0Chapter 1 25 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Loops Split horizon with poison
reverse
The rule states thatonce a router learns ofan unreachable route
through an interface,advertise it asunreachable
Routing Loops
8/14/2019 Exploration Routing Semester 2
136/336
ITE PC v4.0Chapter 1 26 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
IP & TTLPurpose of the TTL field
The TTL field is found in an IP header and is
used to prevent packets from endlesslytraveling on a network
How the TTL field works
-TTL field contains a numeric value
The numeric value is decreased by one by
every router on the route to the destination.If numeric value reaches 0 then Packetis discarded.
Routing Protocols Today
8/14/2019 Exploration Routing Semester 2
137/336
ITE PC v4.0Chapter 1 27 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Factors used to determine whether to use RIP or EIGRPinclude
-Network size
-Compatibility between models of routers-Administrative knowledge
8/14/2019 Exploration Routing Semester 2
138/336
8/14/2019 Exploration Routing Semester 2
139/336
ITE PC v4.0Chapter 1 29 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Routing Protocols Today EIGRP
Features of EIGRP:-Triggered updates
-EIGRP hello protocol used to establish
neighbor adjacencies
-Supports VLSM & route summarization
-Use of topology table to maintain all routes
-Classless distance vector routing protocol
-Cisco proprietary protocol
8/14/2019 Exploration Routing Semester 2
140/336
8/14/2019 Exploration Routing Semester 2
141/336
ITE PC v4.0Chapter 1 31 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Summary D.V. routing protocols maintains routing tables byRIP sending out periodic updates
RIP using 4 different timers to ensure information is accurateand convergence is achieved in a timely manner
EIGRP sending out triggered updates
D.V. routing protocols may be prone to routing loops
routing loops are a condition in which packets continuouslytraverse a network
Mechanisms used to minimize routing loops include defining
maximum hop count, holddown timers, split horizon, routepoisoning and triggered updates
Summary
8/14/2019 Exploration Routing Semester 2
142/336
ITE PC v4.0Chapter 1 32 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Conditions that can lead to routing loops include
Incorrectly configured static routes
Incorrectly configured route redistribution
Slow convergence
Incorrectly configured discard routes
How routing loops can impact network performanceincludes:
Excess use of bandwidth
CPU resources may be strained
Network convergence is degraded
Routing updates may be lost or not processed
8/14/2019 Exploration Routing Semester 2
143/336
ITE PC v4.0Chapter 1 33 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Summary Routing Information Protocol (RIP)
A distance vector protocol that has 2 versions
RIPv1 a classful routing protocol
RIPv2 - a classless routing protocol
Enhanced Interior Gateway Routing Protocol(EIGRP)
A distance vector routing protocols that has some features oflink state routing protocols
A Cisco proprietary routing protocol
8/14/2019 Exploration Routing Semester 2
144/336
8/14/2019 Exploration Routing Semester 2
145/336
2007 Cisco Systems, Inc. All rights reserved. Cisco PublicITE PC v4.0Chapter 1 1
RIP version 1
Routing Protocols andConcepts Chapter 5
8/14/2019 Exploration Routing Semester 2
146/336
ITE PC v4.0Chapter 1 2 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Objectives Describe the functions, characteristics, and operationof the RIPv1 protocol.
Configure a device for using RIPv1. Verify proper RIPv1 operation.
Describe how RIPv1 performs automatic
summarization.
Configure, verify, and troubleshoot default routespropagated in a routed network implementing RIPv1.
Use recommended techniques to solve problemsrelated to RIPv1
8/14/2019 Exploration Routing Semester 2
147/336
ITE PC v4.0Chapter 1 3 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
RIPv1 RIP Characteristics
-A classful, Distance Vector (DV) routing protocol-Metric = hop count
-Routes with a hop count > 15 are unreachable
-Updates are broadcast every 30 seconds
RIPv1
8/14/2019 Exploration Routing Semester 2
148/336
ITE PC v4.0Chapter 1 4 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
RIP Message Format RIP header - divided into
3 fields
-Command field-Version field
-Must be zero
Route Entry - composedof 3 fields
-Address familyidentifier
-IP address
-Metric
8/14/2019 Exploration Routing Semester 2
149/336
ITE PC v4.0Chapter 1 5 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
RIPv1 RIP Operation
RIP uses 2 message types:
Request message
-This is sent out on startup by each RIP
enabled interface-Requests all RIP enabled neighbors to sendrouting table
Response message
-Message sent to requesting routercontaining routing table
RIPv1
8/14/2019 Exploration Routing Semester 2
150/336
ITE PC v4.0Chapter 1 6 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
IP addresses initially dividedinto classes
-Class A-Class B
-Class C
RIP is a classful routingprotocol
-Does not send subnetmasks in routing updates
RIPv1
8/14/2019 Exploration Routing Semester 2
151/336
ITE PC v4.0Chapter 1 7 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Administrative DistanceRIPs default administrative distance is 120
Basic RIPv1 Configuration
8/14/2019 Exploration Routing Semester 2
152/336
ITE PC v4.0Chapter 1 8 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Basic RIPv1 Configuration A typical topology suitable for
use by RIPv1 includes:
-Three router set up-No PCs attached to LANs
-Use of 5 different IP
subnets
Basic RIPv1 Configuration
8/14/2019 Exploration Routing Semester 2
153/336
ITE PC v4.0Chapter 1 9 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Router RIP Command
To enable RIP enter:
-Router ripat the global configuration prompt-Prompt will look like R1(config-router)#
Basic RIPv1 Configuration
8/14/2019 Exploration Routing Semester 2
154/336
ITE PC v4.0Chapter 1 10 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Specifying Networks
Use the networkcommand to:
-Enable RIP on allinterfaces thatbelong to this
network
-Advertise thisnetwork in RIP
updatessent to otherrouters
every 30 seconds
Verification and Troubleshooting
8/14/2019 Exploration Routing Semester 2
155/336
ITE PC v4.0Chapter 1 11 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Show ip Route
To verify andtroubleshoot routing
-Use the following
commands:
-show ip route
-show ip protocols
-debug ip rip
Verification and Troubleshooting
8/14/2019 Exploration Routing Semester 2
156/336
ITE PC v4.0Chapter 1 12 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
show ipprotocols
command-Displaysrouting
protocolconfiguredon router
Verification and Troubleshooting Debug ip rip command
8/14/2019 Exploration Routing Semester 2
157/336
ITE PC v4.0Chapter 1 13 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
ebug p p co a d
-Used to display RIP routing updates as they arehappening
Verification and Troubleshooting
8/14/2019 Exploration Routing Semester 2
158/336
ITE PC v4.0Chapter 1 14 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
e cat o a d oub es oot g
Passive interface command
-Used to prevent a router from sending updates throughan interface
-Example:
Router(config-router)#passive-interface interface-type interface-number
Verification and Troubleshooting
8/14/2019 Exploration Routing Semester 2
159/336
ITE PC v4.0Chapter 1 15 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
g Passive interfaces
Automatic SummarizationModified Topology
8/14/2019 Exploration Routing Semester 2
160/336
ITE PC v4.0Chapter 1 16 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
p gy
The original scenario has beenmodified such that:
Three classful networks are used:
172.30.0.0/16
192.168.4.0/24
192.168.5.0/24
The 172.30.0.0/16 network issubnetted into three subnets:
172.30.1.0/24
172.30.2.0/24
172.30.3.0/24
The following devices are part of the172.30.0.0/16 classful network address:
All interfaces on R1S0/0/0 and Fa0/0 on R2
Automatic Summarization
8/14/2019 Exploration Routing Semester 2
161/336
ITE PC v4.0Chapter 1 17 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Configuration Details
-To remove the RIP routing
process use the followingcommand
No router rip
-To check the configurationuse the following command
Show run
Automatic Summarization Boundary Routers
8/14/2019 Exploration Routing Semester 2
162/336
ITE PC v4.0Chapter 1 18 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
y
RIP automatically summarizes classful networks
Boundary routers summarize RIP subnets from one
major network to another.
Automatic Summarization
8/14/2019 Exploration Routing Semester 2
163/336
ITE PC v4.0Chapter 1 19 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Processing RIP Updates
2 rules govern RIPv1 updates:
-If a routing update and the interface itsreceived on belong to the samenetwork then
The subnet mask of theinterface is applied to the
network in the routing update
-If a routing update and the interface itsreceived on belong to a differentnetwork then
The classful subnet mask of thenetwork is applied to thenetwork in the routing update.
Automatic Summarization
8/14/2019 Exploration Routing Semester 2
164/336
ITE PC v4.0Chapter 1 20 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Sending RIPUpdates
RIP usesautomaticsummarization to reduce
the size of arouting table.
Automatic Summarization
8/14/2019 Exploration Routing Semester 2
165/336
ITE PC v4.0Chapter 1 21 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Advantages of automaticsummarization:
-The size ofrouting updates isreduced
-Single routes areused to representmultiple routeswhich results in
faster lookup in therouting table.
Automatic Summarization
8/14/2019 Exploration Routing Semester 2
166/336
ITE PC v4.0Chapter 1 22 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Disadvantage of Automatic Summarization:
-Does not support discontiguous networks
Automatic Summarization
8/14/2019 Exploration Routing Semester 2
167/336
ITE PC v4.0Chapter 1 23 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
DiscontiguousTopologies do not
converge with RIPv1
A router will only
advertise majornetwork addressesout interfaces that do
not belong to theadvertised route.
Default Route and RIPv1
8/14/2019 Exploration Routing Semester 2
168/336
ITE PC v4.0Chapter 1 24 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Modified Topology: Scenario C
Default routes
Packets that are not defined specifically in a routingtable will go to the specified interface for the defaultroute
Example: Customer routers use default routes toconnect to an ISP router.
Command used to configure a default route is
ip route 0.0.0.0 0.0.0.0 s0/0/1
Default Route and RIPv1
8/14/2019 Exploration Routing Semester 2
169/336
ITE PC v4.0Chapter 1 25 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Default Route and RIPv1
8/14/2019 Exploration Routing Semester 2
170/336
ITE PC v4.0Chapter 1 26 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Propagating the DefaultRoute in RIPv1
Default-informationoriginate command
-This command is used to specify that therouter is to originate default information,
by propagating the static default route inRIP update.
8/14/2019 Exploration Routing Semester 2
171/336
Summary: Commands used by RIP
8/14/2019 Exploration Routing Semester 2
172/336
ITE PC v4.0Chapter 1 28 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Command Commands purpose
Rtr(config)#router rip Enables RIP routing process
Rtr(config-router)#network Associates a network with a RIP routing process
Rtr#debug ip rip used to view real time RIP routing updates
Rtr(config-router)#passive-interface fa0/0 Prevent RIP updates from going out an interface
Rtr(config-router)#default-information originate Used by RIP to propagate default routes
Rtr#show ip protocols Used to display timers used by RIP
8/14/2019 Exploration Routing Semester 2
173/336
8/14/2019 Exploration Routing Semester 2
174/336
2007 Cisco Systems, Inc. All rights reserved. Cisco PublicITE PC v4.0Chapter 1 1
VLSM and CIDR
Routing Protocols and
Concepts Chapter 6
ObjectivesC d l f l d l l IP
8/14/2019 Exploration Routing Semester 2
175/336
ITE PC v4.0Chapter 1 2 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Compare and contrast classful and classless IPaddressing.
Review VLSM and explain the benefits of classless IPaddressing.
Describe the role of the Classless Inter-Domain
Routing (CIDR) standard in making efficient use ofscarce IPv4 addresses
Introduction
P i t 1981 IP dd d l th fi t 8 bit t
8/14/2019 Exploration Routing Semester 2
176/336
ITE PC v4.0Chapter 1 3 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Prior to 1981, IP addresses used only the first 8 bits tospecify the network portion of the address
In 1981, RFC 791 modified the IPv4 32-bit address to
allow for three different classes IP address space was depleting rapidly
the Internet Engineering Task Force (IETF)
introduced Classless Inter-Domain Routing (CIDR)
CIDR uses Variable Length Subnet Masking(VLSM) to help conserve address space.
-VLSM is simply subnetting a subnet
Classful and Classless IP Addressing
Cl f l IP dd i
8/14/2019 Exploration Routing Semester 2
177/336
ITE PC v4.0Chapter 1 4 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classful IP addressing As of January 2007, there
are over 433 million hostson Internet
Initiatives to conserve IPv4address space include:
-VLSM & CIDR notation(1993, RFC 1519)
-Network AddressTranslation (1994, RFC1631)
-Private Addressing(1996, RFC 1918)
8/14/2019 Exploration Routing Semester 2
178/336
Classful and Classless IP Addressing Classes of IP addresses are identified by the decimal number of
th 1 t t t
8/14/2019 Exploration Routing Semester 2
179/336
ITE PC v4.0Chapter 1 6 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
the 1st octet
Class A address begin with a 0 bit
Range of class A addresses = 0.0.0.0 to 127.255.255.255Class B address begin with a 1 bit and a 0 bit
Range of class B addresses = 128.0.0.0 to 191.255.255.255
Class C addresses begin with two 1 bits & a 0 bit
Range of class C addresses = 192.0.0.0 to 223.255.255.255.
Classful and Classless IP Addressing
Th IP Cl f l Add i S (RFC )
8/14/2019 Exploration Routing Semester 2
180/336
ITE PC v4.0Chapter 1 7 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
The IPv4 Classful Addressing Structure (RFC 790)
An IP address has 2 parts:
-The network portion
Found on the left side of an IP address
-The host portionFound on the right side of an IP address
Classful and Classless IP Addressing
8/14/2019 Exploration Routing Semester 2
181/336
ITE PC v4.0Chapter 1 8 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classful and Classless IP Addressing
8/14/2019 Exploration Routing Semester 2
182/336
ITE PC v4.0Chapter 1 9 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Purpose of a subnet mask
It is used to determine the network portion of an IPaddress
Classful and Classless IP Addressing
Classful Routing Updates
8/14/2019 Exploration Routing Semester 2
183/336
ITE PC v4.0Chapter 1 10 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classful Routing Updates-Recall that classful routing protocols (i.e. RIPv1)do not send subnet masks in their routing updates
The reason is that the Subnet mask isdirectly related to the network address
Classful and Classless IP Addressing
8/14/2019 Exploration Routing Semester 2
184/336
ITE PC v4.0Chapter 1 11 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classless Inter-domain Routing (CIDR RFC 1517)
Advantage of CIDR :
-More efficient use of IPv4 addressspace
-Route summarization
Requires subnet mask to be included in routing updatebecause address class is meaningless
Recall purpose of a subnet mask:
-To determine the network and host portionof an IP address
Classful and Classless IP Addressing
Classless IP Addressing
8/14/2019 Exploration Routing Semester 2
185/336
ITE PC v4.0Chapter 1 12 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classless IP Addressing
CIDR & Route Summarization
-Variable Length Subnet Masking (VLSM)-Allows a subnet to be further sub-netted
according to individual needs
-Prefix Aggregation a.k.a. Route Summarization
-CIDR allows for routes to be summarized as asingle route
Classful and Classless IP Addressing
8/14/2019 Exploration Routing Semester 2
186/336
ITE PC v4.0Chapter 1 13 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classful and Classless IP Addressing
8/14/2019 Exploration Routing Semester 2
187/336
ITE PC v4.0Chapter 1 14 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classless Routing Protocol
Characteristics of classless routing protocols:
-Routing updates include the subnet mask
-Supports VLSM
Supports Route Summarization
Classful and Classless IP Addressing
8/14/2019 Exploration Routing Semester 2
188/336
ITE PC v4.0Chapter 1 15 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classful and Classless IP Addressing
8/14/2019 Exploration Routing Semester 2
189/336
ITE PC v4.0Chapter 1 16 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
RoutingProtocol
Routingupdates
Include
subnetMask
SupportsVLSM
Ability to sendSupernet routes
Classful No No No
Classless Yes Yes Yes
Classless Routing Protocol
VLSM
Classful routing
8/14/2019 Exploration Routing Semester 2
190/336
ITE PC v4.0Chapter 1 17 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classful routing-only allows for onesubnet mask for allnetworks
VLSM & classless routing
-This is the processof subnetting a subnet
-More than onesubnet mask can beused
-More efficient use of IPaddresses as comparedto classful IP
addressing BACKBONE
VLSM
VLSM the process of
8/14/2019 Exploration Routing Semester 2
191/336
ITE PC v4.0Chapter 1 18 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
VLSM the process ofsub-netting a subnet to fityour needs
-Example:
Subnet 10.1.0.0/16, 8more bits are borrowed
again, to create 256subnets with a /24 mask.
-Mask allows for 254 host
addresses per subnet
-Subnets range from:10.1.0.0 / 24 to
10.1.255.0 / 24
Classless Inter-Domain Routing (CIDR)
Route summarization done by CIDR
8/14/2019 Exploration Routing Semester 2
192/336
ITE PC v4.0Chapter 1 19 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Route summarization done by CIDR-Routes are summarized with masks that are lessthan that of the default classful mask
-Example:
172.16.0.0 /13 is the summarizedroute for the 172.16.0.0 /16 to172.23.0.0 /16 classful networks
Classless Inter-Domain Routing (CIDR)
8/14/2019 Exploration Routing Semester 2
193/336
ITE PC v4.0Chapter 1 20 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Steps to calculate a routesummary
-List networks in binaryformat
-Count number of left
most matching bits todetermine summaryroutes mask
-Copy the matchingbits and add zero bitsto determine thesummarizednetwork address
Summary
Classful IP addressing
8/14/2019 Exploration Routing Semester 2
194/336
ITE PC v4.0Chapter 1 21 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classful IP addressingIPv4 addresses have 2 parts:
-Network portion found on left side of an IP
address-Host portion found on right side of an IPaddress
Class A, B, & C addresses were designed to provide IPaddresses for different sized organizations
The class of an IP address is determined by the decimalvalue found in the 1st octet
IP addresses are running out so the use of Classless InterDomain Routing (CIDR) and Variable Length Subnet Mask(VLSM) are used to try and conserve address space
Summary
Classful Routing Updates
8/14/2019 Exploration Routing Semester 2
195/336
ITE PC v4.0Chapter 1 22 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Classful Routing UpdatesSubnet masks are not sent in routing updates
Classless IP addressing
Benefit of classless IP addressing
Can create additional network
addresses using a subnet maskthat fits your needs
Uses Classless Interdomain Routing (CIDR)
Summary CIDR
8/14/2019 Exploration Routing Semester 2
196/336
ITE PC v4.0Chapter 1 23 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
CIDR
Uses IP addresses more efficiently through
use of VLSM-VLSM is the process ofsubnetting a subnet
Allows for route summarization-Route summarization isrepresenting multiple contiguous
routes with a single route
8/14/2019 Exploration Routing Semester 2
197/336
8/14/2019 Exploration Routing Semester 2
198/336
ITE PC v4.0Chapter 1 25 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
8/14/2019 Exploration Routing Semester 2
199/336
2007 Cisco Systems, Inc. All rights reserved. Cisco PublicITE PC v4.0Chapter 1 1
RIPv2
Routing Protocols and
Concepts Chapter 7
Objectives Encounter and describe the limitations of RIPv1s
8/14/2019 Exploration Routing Semester 2
200/336
ITE PC v4.0Chapter 1 2 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Encounter and describe the limitations of RIPv1 slimitations.
Apply the basic Routing Information Protocol Version2 (RIPv2) configuration commands and evaluateRIPv2 classless routing updates.
Analyze router output to see RIPv2 support for VLSMand CIDR
Identify RIPv2 verification commands and commonRIPv2 issues.
Configure, verify, and troubleshoot RIPv2 in hands-on labs
Introduction
Chapter focus
8/14/2019 Exploration Routing Semester 2
201/336
ITE PC v4.0Chapter 1 3 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Chapter focus-Difference between RIPv1 & RIPv2
RIPv1
-A classful distance vector routing protocol-Does not support discontiguous subnets
-Does not support VLSM
-Does not send subnet mask in routing update
-Routing updates are broadcastRIPv2
-A classless distance vector routing protocol that is anenhancement of RIPv1s features.
-Next hop address is included in updates
-Routing updates are multicast
-The use of authentication is an option
Introduction
8/14/2019 Exploration Routing Semester 2
202/336
ITE PC v4.0Chapter 1 4 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Similarities between RIPv1 & RIPv2
-Use of timers to prevent routing loops-Use of split horizon or split horizon with poisonreverse
-Use of triggered updates
-Maximum hop count of 15
RIPv1 Limitations
Lab Topology
8/14/2019 Exploration Routing Semester 2
203/336
ITE PC v4.0Chapter 1 5 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
ab opo ogy
Scenario:
3 router set up
Topology is discontiguous
There exists a static summaryroute
Static route information can beinjected into routing table updatesusing redistribution.
Routers 1 & 3 contain VLSMnetworks
8/14/2019 Exploration Routing Semester 2
204/336
RIPv1 Limitations Null Interfaces
8/14/2019 Exploration Routing Semester 2
205/336
ITE PC v4.0Chapter 1 7 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
This is a virtual interface that does not need to becreated or configured
-Traffic sent to a null interface is discarded
-Null interfaces do not send or receive traffic
Static routes and null interfaces
null interfaces will serve as the exit interface forstatic route
-Example of configuring a static supernet route with anull interface
-R2(config)#ip route 192.168.0.0 255.255.0.0 Null0
8/14/2019 Exploration Routing Semester 2
206/336
RIPv1 Limitations
8/14/2019 Exploration Routing Semester 2
207/336
ITE PC v4.0Chapter 1 9 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Verifying and Testing Connectivity
Use the following commands: show ip interfaces brief
ping
traceroute
RIPv1 Limitations
RIPv1 a classful routing protocol
8/14/2019 Exploration Routing Semester 2
208/336
ITE PC v4.0Chapter 1 10 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
RIPv1 a classful routing protocol
-Subnet mask are not sent in updates
-Summarizes networks at major network boundaries
-if network is discontiguous and RIPv1 configured
convergencewill not be reached
RIPv1 Limitations
Examining the routing tables
8/14/2019 Exploration Routing Semester 2
209/336
ITE PC v4.0Chapter 1 11 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
g g
-To examine the contents ofrouting updates use the
debug ip ripcommand
-If RIPv1 is
configured thenSubnet masks will not beincluded with the
network address
RIPv1 Limitations
RIPv1 does not supportVLSM
8/14/2019 Exploration Routing Semester 2
210/336
ITE PC v4.0Chapter 1 12 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
ppVLSM
Reason: RIPv1 does not
send subnet maskin routing updates
RIPv1 does summarize
routes to the Classfulboundary
Or uses the Subnet mask
of the outgoing interfaceto determine whichsubnets to advertise
RIPv1 Limitations
8/14/2019 Exploration Routing Semester 2
211/336
ITE PC v4.0Chapter 1 13 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
No CIDR Support
In the diagram R2 will not
include the static route in itsupdate
Reason: Classful routingprotocols do not supportCIDR routes that aresummarized with a smallermask than the classfulsubnet mask
8/14/2019 Exploration Routing Semester 2
212/336
Configuring RIPv2
8/14/2019 Exploration Routing Semester 2
213/336
ITE PC v4.0Chapter 1 15 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Enabling and Verifying RIPv2
Configuring RIP on a Cisco routerBy default it is running RIPv1
8/14/2019 Exploration Routing Semester 2
214/336
8/14/2019 Exploration Routing Semester 2
215/336
Di bli A t
Configuring RIPv2
8/14/2019 Exploration Routing Semester 2
216/336
ITE PC v4.0Chapter 1 18 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Disabling Auto-Summary in RIPv2
To disable automaticsummarization issuethe no auto-summary
command
8/14/2019 Exploration Routing Semester 2
217/336
8/14/2019 Exploration Routing Semester 2
218/336
VLSM & CIDR
8/14/2019 Exploration Routing Semester 2
219/336
ITE PC v4.0Chapter 1 21 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
CIDR uses Supernetting
Supernetting is a bunch of contiguous classfulnetworks that is addressed as a singlenetwork.
VLSM & CIDR
To verify that
8/14/2019 Exploration Routing Semester 2
220/336
ITE PC v4.0Chapter 1 22 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
To verify thatsupernets arebeing sent andreceived use thefollowing commands
-Show ip route
-Debug ip rip
Verifying & Troubleshooting RIPv2
Basic Troubleshooting stepsCh k th t t f ll li k
8/14/2019 Exploration Routing Semester 2
221/336
ITE PC v4.0Chapter 1 23 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
-Check the status of all links
-Check cabling
-Check IP address & subnet mask configuration
-Remove any unneeded configuration commands
Commands used to verify proper operation of RIPv2
Show ip interfaces brief
Show ip protocolsDebug ip rip
Show ip route
Verifying & Troubleshooting RIPv2
Common RIPv2 Issues
8/14/2019 Exploration Routing Semester 2
222/336
ITE PC v4.0Chapter 1 24 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Common RIPv2 Issues
When trouble shooting RIPv2 examine the following issues:
Version
Check to make sure you are using version 2
Network statements
Network statements may be incorrectly typedor missing
Automatic summarization
If summarized routes are not needed then disableautomatic summarization
Verifying & Troubleshooting RIPv2
Reasons why its good to authenticate routing information
8/14/2019 Exploration Routing Semester 2
223/336
ITE PC v4.0Chapter 1 25 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
-Prevent the possibility of accepting invalid routingupdates
-Contents of routing updates are encrypted
Types of routing protocols that can use authentication
-RIPv2
-EIGRP
-OSPF
-IS-IS
-BGP
8/14/2019 Exploration Routing Semester 2
224/336
8/14/2019 Exploration Routing Semester 2
225/336
ITE PC v4.0Chapter 1 27 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
8/14/2019 Exploration Routing Semester 2
226/336
2007 Cisco Systems, Inc. All rights reserved. Cisco PublicITE PC v4.0Chapter 1 1
The Routing Table: ACloser Look
Routing Protocols and
Concepts Chapter 8
Objectives Describe the various route types found in the routing
table structure
8/14/2019 Exploration Routing Semester 2
227/336
ITE PC v4.0Chapter 1 2 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
table structure
Describe the routing table lookup process.
Describe routing behavior in routed networks.
Introduction
8/14/2019 Exploration Routing Semester 2
228/336
ITE PC v4.0Chapter 1 3 2007 Cisco Systems, Inc. Al