TCP/IP & ROUTING PROTOCOLS V.Maheswaran Nair Sub Divisional Engineer BSNL,Trivandrum.
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TCP/IP
&
ROUTING PROTOCOLS
V.Maheswaran Nair
Sub Divisional Engineer
BSNL,Trivandrum.
TCP/IP(Transmission Control Protocol/
Internet Protocol)
TCP/IP Protocols provide the ability to connect machines regardless of the underlying network cabling & the Operating Systems in use.
TCP/IP is a piece of networking software for the Internet and networks worldwide.
TCP/IP
TCP/IP protocol suite contain two main things:
Network Applications HTTP (Hyper Text Transfer Protocol) WWW
Services
FTP (File Transfer Protocol) for transferring file
SMTP Simple Mail Transfer Protocol) for E Mail
DNS (Domain Name System) etc…
TCP is Used
Networking protocols
Moving packet of data from Source to Destination
Internet Protocols (IP) and Routing Protocols are used.
TCP is responsible for:
Data concurrency
Packet Sequencing
Delivery guarantee
Error Control
Retransmission
Internet address
MAC address
(Node to Node)
IP address
(Source to
Destination)
Port address
(Application)
16 bit
Decimal Notation
MAC address
48 bit (6 Bytes)
Hexa Decimal Notation
AB 0F 25 B6 C5 D2
Vendor ID Serial No
IP Address
Each Internet address consists of 4 bytes (32-bits), defining two parts:
Hostid
Netid
These parts are of varying lengths depending upon the class of the address.
Dotted Decimal Notation
128.11.3.31
10000000 00001011 00000011 00011111
Classes
There are five different IP Address Classes: A, B, C, D & E.
These are designed to cover the needs of different types of organizations.
Host IdNet Id
NIB
Each address is a pair (Netid and Hostid) where the Netid identifies a network and the Hostid identifies a host on that network.
IP Address Classes
Class A Address : N.H.H.H Class B Address : N.N.H.H Class C Address : N.N.N.H
IP address - Classes
Class A 00xxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
Network Host
Class B
Network Host
1010xxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
Class C
Network Host
110110xxxxx xxxxxxxx xxxxxxxx xxxxxxxx
•IP addressing supports five different address classes - A, B,C,D,E•CLASS A,B,C are available for commercial uses.•The left most bits indicate the network class.
Identifying a class of address
Address Identifier Network Id Host Id
0 7 bits Network Bits 24 bits Host IdA
10 14 bits Network Bits 16 bits Host IdB
110 21 bits Network Bits 8 bits Host IdC
1110 Multicast address (224.0.0.0-239.255.255.255)D
1111 Reserved for future useE
IP Address Bit Patterns
8 Bits8 Bits 8 Bits 8 Bits
Class-A:
Class-B:
Class-C:
Class-D:
Class-E:
0-127
128-191
192-223
224-239
240-255
0 0 0 0 0 0 0 0
1 0 0 0 0 0 0 0
1 1 0 0 0 0 0 0
1 1 1 0 0 0 0 0
1 1 1 1 0 0 0 0
0 1 1 1 1 1 1 1
1 0 1 1 1 1 1 1
1 1 0 1 1 1 1 1
1 1 1 0 1 1 1 1
1 1 1 1 1 1 1 1
Address space utilisation
01
0
127
00000000
01111111
A-50%
1
0
128
191
10000000
10111111
B-25%
0
1
192
223
11000000
11011111
C-12.5%
240 25
5111100001111111
1
E-6.25%
022423
9
11100000 1110111
1
D-6.25%0
1
100%
0.0.0.0 127.255.255.255
128.0.0.0 191.255.255.255
192.0.0.0 223.255.255.255
224.0.0.0 239.255.255.255
240.0.0.0 255.255.255.255
A
B
C
D
E
FROM TO
Class No. of networks No. of hosts
A 27 – 2 = 126 224 – 2 = 16,777,214
B 214 = 16,384 216 – 2 = 65,534
C 221 = 2,097,152 28 – 2 = 254
D Not Applicable Not Applicable
E Not Applicable Not Applicable
Number of networks and hosts in each Class
TCP/IP and OSI
OSI is made of seven layers. TCP/IP protocol is made of five layers.
PHYSICAL
DATA LINK
NETWORK
TRANSPORT
APPLICATION
PHYSICAL
DATA LINK
NETWORK
TRANSPORT
SESSION
PRESENTATION
APPLICATION
OSI Model TCP/IP Model
TCP/IP Protocol Suite
D
N
T
A
ICMP IGMPRARPARP
FTPDHCP SMTP
TELNETHTTP
TFTPSNMPDNS
TCP UDP
IP
Protocols defined by the underlying networks
P
Ethernet, Token Ring, FDDI, HDLC, FR, PPP, ATM
Data Encapsulation
Frame
Data
DataPort add (TCP)
TCP Segment
DataPort add (UDP)
UDP Message
Dest MACSource MAC IP Header TCP-UDP Data
TCP-UDP DataSource IP Dest IP
Application
TPT Layer (TCP/UDP)
NW Layer (IP)
Data Link (MAC)
Physical Bits 10000010101001
IP Datagram
Well known port numbers
PORT DESCRIPTION
20 File Transfer-Data
21 File Transfer-Control
23 Telnet
25 SMTP
53 Domain Name Server
69 Trivial File Transfer
80 WWW
123 Network Time Protocol
179 Border Gateway Protocol
Domain Name System (DNS)
What is the IP Address of www.Yahoo.com
What is the IP Address of www.Yahoo.com
www.yahoo.com , IP address is 210.212.90.15
www.yahoo.com , IP address is 210.212.90.15
User traffic
yahoo.com
DNS Server
DNS Server
Internet
ROUTING PROTOCOLS
Routing Protocol
It is a language a router speaks with other routers
Functions of RP Forwarding, Sharing Updating
information about the reachability and status of the network
Static Routing
Routes to destinations are set up manually Route may be up or down but static routes
will remain in the routing tables and traffic would still be sent towards the route
Not suitable for large networks Also known as Non-adaptive routing
Dynamic Routing
Routes are learnt via an internal or external routing protocols
Network reachability is dependent on the existence and state of the network
Routing decisions change to reflect the changes in topology
Also known as Adaptive routing
Routing Table
A Data base to be maintained by each router.
Created by using algorithms.It contains
Network addressInterface address for reaching the next router (Hope)
Metric
Types of R P
Routes
Static
Dynamic
Distance Vector Protocols
Link State Protocols
RIP,IGRP
OSPF,IS-IS
Routing Protocols contd..
Distance Vector Routing Protocols eg. RIP V1 (Routing Information protocol)
RIP V2 Link State Routing Protocols eg. OSPF (Open Shortest Path First)
IS-IS (Intermediate System-Intermediate System)
Metrics Hop Count -- Distance Vector
Cost (BW) – Link State
Routing Updates
After exchanging 2 periodic updates, the network is converged.
21.0.0.020.0.0.0 22.0.0.0 23.0.0.0
.2.1 .2.1 .1.2
A B C
23.0.0.0 21.0.0.2 2 20.0.0.0 22.0.0.1 2
22.0.0.0 21.0.0.2 1 20.0.0.0 21.0.0.1 123.0.0.0 22.0.0.2 1
21.0.0.0 22.0.0.1 1
NW VIA HOP20.0.0.0 ---------- 021.0.0.0 ---------- 0
NW VIA HOP21.0.0.0 ---------- 022.0.0.0 ---------- 0
NW VIA HOP22.0.0.0 ---------- 023.0.0.0 ---------- 0
Routing Table-A Routing Table-B Routing Table-C
20.0.0.10 23.0.0.15
Routing Updates
Router-C in its next scheduled update, flags the network as unreachable and passes the information along.
21.0.0.020.0.0.0 22.0.0.0 23.0.0.0
.2.1 .2.1 .1.2
A B C
NW VIA HOP20.0.0.0 D 021.0.0.0 D 022.0.0.0 21.0.0.2 123.0.0.0 21.0.0.2 2
Routing Table-A
Routing Table-B
Routing Table-C
NW VIA HOP20.0.0.0 21.0.0.1 121.0.0.0 D 022.0.0.0 D 023.0.0.0 22.0.0.2 1
NW VIA HOP20.0.0.0 22.0.0.1 221.0.0.0 22.0.0.1 122.0.0.0 D 023.0.0.0 D 023.0.0.0 C UR23.0.0.0 22.0.0.2 UR23.0.0.0 21.0.0.2 UR
Routing Updates
Routers-A & B still have entries in the route table about 23.0.0.0.
The information is no longer valid but there is no router to inform them of this fact, thus creating a black-hole in the network.
21.0.0.020.0.0.0 22.0.0.0 23.0.0.0
.2.1 .2.1 .1.2
A B C
NW VIA HOP20.0.0.0 D 021.0.0.0 D 022.0.0.0 21.0.0.2 123.0.0.0 21.0.0.2 2
Routing Table-A
Routing Table-B
Routing Table-C
NW VIA HOP20.0.0.0 21.0.0.1 121.0.0.0 D 022.0.0.0 D 023.0.0.0 22.0.0.2 1
NW VIA HOP20.0.0.0 22.0.0.1 221.0.0.0 22.0.0.1 122.0.0.0 D 023.0.0.0 D 0
Route Invalidation Timer
Another Timer, Garbage Collection or Flush Timer, 60 Seconds longer than RIT, is set.
On the expiry of which the route entry will be flushed from the routing table.
21.0.0.020.0.0.0 22.0.0.0 23.0.0.0
.2.1 .2.1 .1.2
A B C
NW VIA HOP TIME20.0.0.0 C 0 RIT21.0.0.0 C 0 RIT22.0.0.0 21.0.0.2 1 RIT23.0.0.0 21.0.0.2 2 RIT
Routing Table-A
Routing Table-B
Routing Table-C
NW VIA HOP TIME20.0.0.0 21.0.0.1 1 RIT21.0.0.0 C 0 RIT22.0.0.0 C 0 RIT23.0.0.0 22.0.0.2 1 RIT
NW VIA HOP TIME20.0.0.0 22.0.0.1 2 RIT21.0.0.0 22.0.0.1 1 RIT22.0.0.0 C 0 RIT23.0.0.0 C 0 RIT0 023.0.0.0 22.0.0.2 UR23.0.0.0 21.0.0.2 UR
RIP Timers
Update Timer 30 Seconds
Route Invalidation Timer 180 Seconds (6 Times the Update Timer)
Garbage Collection Timer 240 seconds (60 Seconds longer than RIT)
OSPF operation….
OSPF- Routers send Hello packets out OSPF-enabled interfaces
Two routers sharing a common link, after exchanging Hello packets, become neighbors
OSPF operation…
Link State Advertisements (LSAs) i.e. router’s links and their state, are exchanged between adjacent routers
Each router receiving an LSA from a neighbor records the LSA in Link State Database and sends a copy of the LSA to all of its other neighbors
LSAs are exchanged, until all the routers build identical Link State Databases i.e. the link state databases have been synchronized
OSPF operation….
Each router uses SPF algorithm to calculate a shortest path to every known destination, with itself as root
Each router builds its router table from its SPF Tree
After this, in a stable internetwork, all activities stop except Hello packets are exchanged, after regular intervals of
10 seconds (Hello Interval) between neighbors, as keepalives
LSAs are exchanged every 30 minutes
Metrics
Speed Cost
>= 100Mbps 1
Ethernet/802.3 10
E1(2.048Mbps) 48
64Kbps 1562
Metric=108/Interface Speed in bits per sec.e.g. 100000000/2048000=48.828125
Shortest Path Tree of Router-A
A B
C D
4 4
20 5
2 2
5 3
3
A B
C D
4
5
2
20
PATH VECTOR ROUTING
Path vector routing is similar to distance Path vector routing is similar to distance vector routing. There is at least one node, vector routing. There is at least one node, called the speaker node, in each AS that called the speaker node, in each AS that creates a routing table and advertises it to creates a routing table and advertises it to speaker nodes in the neighboring ASs..speaker nodes in the neighboring ASs..
Boarder Gateway Protocol
Between Two AS
Autonomous System
DefinitionAn autonomous system is a network
under a common administration
Autonomous systems
Autonomous systems
AS-1 AS-2
AS-0
IGP
IGP IGP
BGP
BGP
BGP
In distance vector routing, each node shares the knowledge about the entire
AS with its immediate neighbors periodically .
Note:Note:
Initial routing tables in path vector routing
Popular routing protocols
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