RIP ( Routing Information Protocol) RFC 1058 and 1723 Included in BSD UNIX in 1982 Distance vector algorithm Distance metric: number of hops (max = 15.

RIP ( Routing Information Protocol)

• RFC 1058 and 1723• Included in BSD UNIX in 1982• Distance vector algorithm• Distance metric: number of hops (max = 15 hops)• Distance vectors: exchanged every 30 sec via RIP Re

sponse Message (also called “RIP advertisement”)• 封装在 UDP 报文中 , 端口号为 520 。

Routing Information Protocol (RIP v1)

命令字： 1 请求； 2 响应通常把命令域设为 1 ，然后广播整个路由表

metric

Command (1-6) Version 0

Address Family 0

32-bit IP address

0

0

24 more routes

RIP: Routing Information ProtocolUses hop count as metric (max: 16 is infinity) Tables (vectors) “advertised” to neighbors every 30 s.

Each advertisement: up to 25 entriesNo advertisement for 180 sec: neighbor/link declared

deadroutes via neighbor invalidatednew advertisements sent to neighbors (Triggered updates)neighbors in turn send out new advertisements (if tables

changed)link failure info quickly propagates to entire netpoison reverse used to prevent ping-pong loops (infinite

distance = 16 hops)

RIPv1 Problems

• Split horizon/poison reverse does not guarantee to solve count-to-infinity problem– 16 = infinity => RIP for small networks only!– Slow convergence

• Broadcasts consume non-router resources

• RIPv1 does not support subnet masks (VLSMs) – No authentication

RIPv2

• Provides:– VLSM support– Authentication– Multicasting （地址为： 224.0.0.0)– Tags to support EGP/BGP routes.

• Uses reserved fields in RIPv1 header.

• First route entry replaced by authentication info.

Routing Information Protocol (RIP v2)

metric

Command (1-6) Version 保留Address Family

32-bit IP address

Next hop (32bit)

24 more routes

32-bit Subnet Mask

路由标记

如果在 Address Family 中的数据为 FFFF, 则整个报文为认证（ authentication) 报文。路由标记：可带 AS 号，使 RIP 能够从 EGP/BGP routes. 中接受信息

RIP problems

• Counting-to-infinity problem: – Simple configuration A->B->C. If C fails, B needs

to update and thinks there is a route through A. A needs to update and thinks there is a route thru B.

– No clear solution, except to set “infinity” to be small (eg 16 in RIP)

• Slow convergence after topology change:– Due to count to infinity problem– Also information cannot propagate thru node

until it recalculates routing info.

Properties of Distance Vector Algorithm

• Bad news propagate slowly: the count-to-infinity problem

Properties of Distance Vector Algorithm

• Good news propagate fast

RIP problems (contd)

• Black-holes:– If one node goes broke and advertises route of zero

to several key networks, all nodes immediately point to it.

• Not the optimal routing tables

the simplistic metric resulting in packets being sent over slow links when better paths are available

• Broadcasts consume non-router resources

The Bouncing Effect

A

2

1

1

B

C

B

C 21

dest cost

A

C 11

dest cost

A

B 12

dest cost

X

C Sends Routes to B

A

2 1

B

C

B

C 21

dest cost

A

C 1~

dest cost

A

B 12

dest cost

B Updates Distance to A

A

2 1

B

C

B

C 21

dest cost

A

C 13

dest cost

A

B 12

dest cost

B Sends Routes to C

A

2 1

B

C

B

C 21

dest cost

A

C 13

dest cost

A

B 14

dest cost

C Sends Routes to B

A

2 1

B

C

B

C 21

dest cost

A

C 15

dest cost

A

B 14

dest cost

How are These Loops Caused?

• Observation 1:– B’s metric increases

• Observation 2:– C picks B as next hop to A– But, the implicit path from C to A includes itsel

f!

Solution 1: Holddowns

• If metric increases, delay propagating information– In our example, B delays advertising route– C eventually thinks B’s route is gone, picks its

own route– B then selects C as next hop

• Adversely affects convergence

Other “Solutions”

• Split horizon– C does not advertise route to B– Rule: It is never useful to send information about

a route back in the direction from which it came

• Poisoned reverse– C advertises route to B with infinite distance– Rule: If two routers have routes pointing at each

other ， advertising reverse routes with a metric of 16 breaks the loop immediately

An Example Where Reverse-Poison Fails

1

1 1

1

When the link between C and D fails, C will set its distance to D as However, A will then use B to go to D, and B will use A to go to D because there is no reverse-poison between them After such updates, A (and B) will then report new path to C for D, and C will use the path; we thus have the count-to-infinity problem again

Link State Protocols

• Key: Create a network “map” at each node.

• 1. Node collects the state of its connected links and forms a “Link State Packet” (LSP)

• 2. Flood LSP => reaches every other node in the network and everyone now has a network map.

• 3. Given map, run Dijkstra’s shortest path algorithm (SPF) => get paths to all destinations

• 4. Routing table = next-hops of these paths.

Dijkstra’s algorithm

Net topology, link costs known to all nodes accomplished via “link state

broadcast” all nodes have same info

computes least-cost paths from one node (‘source or root”) to all other nodes gives routing table for that n

ode iterative: after k iterations,

know least cost path to k dest.’s

Notation: c(i,j): link cost from node i

to j. cost infinite if not direct neighbors

D(v): current value of path cost from source to dest. V

p(v): predecessor node along path from source to v, that is next v

N: set of nodes whose least cost path definitively known

Dijkstra’s Algorithm1 Initialization: 2 N = {A} 3 for all nodes v 4 if v adjacent to A 5 then D(v) = c(A,v) 6 else D(v) = infty 7 8 Loop 9 find w not in N such that D(w) is a minimum 10 add w to N 11 update D(v) for all v adjacent to w and not in N: 12 D(v) = min( D(v), D(w) + c(w,v) ) 13 /* new cost to v is either old cost to v or known 14 shortest path cost to w plus cost from w to v */ 15 until all nodes in N

Dijkstra’s algorithm: example

Step012345

start NA

ADADE

ADEBADEBC

ADEBCF

D(B),p(B)2,A2,A2,A

D(C),p(C)5,A4,D3,E3,E

D(D),p(D)1,A

D(E),p(E)infinity

2,D

D(F),p(F)infinityinfinity

4,E4,E4,E

A

ED

CB

F

2

2

13

1

1

2

53

5

Dijkstra’s algorithm, discussion

Algorithm complexity: n nodeseach iteration: need to check all nodes, w, n

ot in Nn*(n+1)/2 comparisons: O(n**2)more efficient implementations possible: O

(nlogn)

OSPF (Open Shortest Path First)

• RFC 2178• A Link State algorithm

– Link costs are configured by network administrator

– Link state packet disseminated to entire AS (via flooding) periodically

– Each router maintains an identical database describing the AS's topology

– Use Dijkstra’s algorithm to compute shortest path routes to all the routers

OSPF Advanced Features• Security: all OSPF messages authenticated (to prevent malicio

us intrusion), TCP connections used• Multiple same-cost paths allowed (only one path in RIP)• Allow each link to have different costs for different TOS (Typ

e of Service) IP Packets – E.g, high-bandwidth satellite link configured to have a low cost for no

n-time-critical traffic and have a high cost for delay-sensitive traffic– Can compute different routes for each type of traffic

• Integrated unicast and multicast support: – Multicast OSPF (MOSPF, RFC 1584) provides simple extensions to

OSPF to provide for multicast routing

• Support for hierarchy within a single AS

Hierarchical OSPF• Two-level hierarchy: local area, backbone

– An AS is configured into areas, each area runs its own OSPF link-state routing algorithm

– One area in AS is configured to be the backbone area, job is to route traffic between other areas in the AS

Four types of OSPF routers:• Internal routers: in non-backbone areas and only perform intra-AS routi

ng• Area border routers: belong to both an area and the backbone, route pac

kets to outside the area• Backbone routers: perform routing within the backbone but are not area

border routers• Boundary routers: connect to other ASs, exchange routing information

with routers in other ASs

Hierarchical OSPF

OSPF in IP Packets

• OSPF is a link-state routing protocol– Relies on IP packets for delivery of routing

information– Uses protocol number 89

IP Header

Protocol Number

Frame Header

CRCPacket Payload

Frame Payload

89 - OSPF 6 - TCP17 - UDP

89 - OSPF 6 - TCP17 - UDP

OSPF TerminologyOSPF Terminology

TokenRing

Interfaces


Neighbors

TokenRing

Interfaces

Neighbors

TokenRing

Interfaces


Cost = 10

Cost = 6Cost = 1785


Neighbors

TokenRing

Interfaces

Area 1Area 0

Cost = 10

Cost = 6Cost = 1785


Autonomous System

Neighbors

TokenRing

Interfaces

Area 1Area 0

Cost = 1785

Cost = 10

Cost = 6

Autonomous System


Neighborship Database

Lists Neighbors

Neighbors

TokenRing

Interfaces

Area 1Area 0

Cost = 10

Cost = 6Cost = 1785

Autonomous System


Topology Database

Lists All Routes


Lists Neighbors

Neighbors

TokenRing

Interfaces

Area 1Area 0

Cost = 1785

Cost = 10

Cost = 6

Autonomous System


RoutingTable

Lists Best Routes

Topology Database

Lists All Routes


Lists Neighbors

Cost = 10

Cost = 1785 Cost = 6

Neighbors

TokenRing

Interfaces

Area 1Area 0

OSPF Topologies

Point-to-Point

NBMA

Broadcast Multiaccess

X.25Frame Relay

OSPF 五类报文• Type1 ,Hello 分组，用来发现和维持邻站的可达性• 2 ， Database Description, 向邻站给出自己的链路

状态数据库中的所有链路状态项目的摘要信息• 3 ， Link State Request 向对方请求发送某些链路

状态项目的详细信息• 4 ， Link State Update 用 Flooding 向全网更新链路

状态• 5 ， Link State Acknowledgement 对链路更新分组

的确认

NeighborshipNeighborship

Hello

afadjfjorqpoeru39547439070713

Router IDHello/dead intervalsNeighborsArea-IDRouter priorityDR IP addressBDR IP addressAuthentication passwordStub area flag

* *

* *

* Entry must match on neighboring routers

Hello

AA

DD EE

CCBB

每两个相邻的路由器 10 秒钟交换 Hello 报文40 秒没收到 Hello 报文，该相邻 Router 不可达

Neighborship (cont.)Neighborship (cont.)

Hello


Router IDHello/dead intervalsNeighborsArea-IDRouter priorityDR IP addressBDR IP addressAuthentication passwordStub area flag

* *

* *

* Entry must match on neighboring routers

Hello

AA

DD EE

CCBB

DR and BDRDR and BDR

DRDR BDRBDR

– Hellos elect DR and BDR to represent segment– Each router then forms adjacency with DR and BDR

– Hello packets exchanged via IP multicast – Router with highest OSPF priority elected

P=1 P=0P=1

Electing the DR and BDRElecting the DR and BDRP=3 P=2

DRDR BDRBDR

Hello

Exchange ProcessExchange Process172.16.5.1/24

E0

172.16.5.2/24

E1A BDown State

Exchange ProcessExchange Process

172.16.5.1/24

E0

172.16.5.2/24

E1

Router BNeighbors List

172.16.5.1/24, int E1

I am router ID 172.16.5.1 and I see no one.

Down State

Init State

A B


E0

I am router ID 172.16.5.2, and I see 172.16.5.1.

172.16.5.2/24

E1


172.16.5.1/24, int E1


Down State

Init State

A B


E0

I am router ID 172.16.5.2, and I see 172.16.5.1.

Router ANeighbors List

172.16.5.2/24, int E0

172.16.5.2/24

E1


172.16.5.1/24, int E1


Down State

Init State

Two-Way State

A B

Discovering RoutesDiscovering Routes

E0

172.16.5.1

DRE0

172.16.5.3

No, I will start exchange because I have a higher router ID.

I will start exchange because I have router ID 172.16.5.1.Hello


Hello


Exstart State

Discovering RoutesDiscovering Routes

Here is a summary of my link-state database.DBD


Exchange State

Here is a summary of my link-state database.DBD


E0

172.16.5.1

DRE0

172.16.5.3

No, I will start exchange because I have a higher router ID.

I will start exchange because I have router ID 172.16.5.1.Hello


Hello


Exstart State

Discovering Routes (cont.)Discovering Routes (cont.)

E0

172.16.5.1

E0

172.16.5.3

Thanks for the information!LSAck


LSAck


DR


I need the complete entry for network 172.16.6.0/24.

Here is the entry for network 172.16.6.0/24.

Thanks for the information!

LSR


LSAck


LSU


Loading State

E0

172.16.5.1

E0

172.16.5.3



LSAck


DR


Full State

I need the complete entry for network 172.16.6.0/24.

Here is the entry for network 172.16.6.0/24.

Thanks for the information!

LSR


LSAck


LSU


Loading State

E0

172.16.5.1

E0

172.16.5.3



LSAck


DR

Choosing RoutesChoosing Routes

Topology TableNet Cost Out Interface10.2.2.0 6 To010.3.3.0 7 To010.3.3.0 10 E0

TokenRing

Cost=10

Cost=6FDDI

Cost=1

A B C

This is the best route to 10.3.3.0.

10.1.1.0/24 10.2.2.0/24 10.3.3.0/24

10.4.4.0/24

Maintaining Routing InformationMaintaining Routing Information

• Router A tells all OSPF DRs on 224.0.0.6

xx

Link-State Change

LSU1

DRDR

AA BB


LSU

2


• DR tells others on 224.0.0.5

xx

Link-State Change

LSU1

DRDR

AA BB

LSU

3


LSU

2

xx

Link-State Change

LSU1

DRDR

AA BB




I need to update my routing table.

4

LSU

3

LSU

2

xx

Link-State Change

LSU1

DRDR

AA BB



Maintaining Routing Information (cont.)


Is entry inlink-state

database? LSA

LSU

No

Run SPF to calculate new routing table

Add to database

Flood LSA

End

Send LSAckto DR



Yes

Is seq. # the same?

Yes

Ignore LSAIs entry inlink-state

database? LSA

LSU

No


Add to database

Flood LSA

Send LSAckto DR

End

32bit 序号，序号越大，状态越新OSPF 规定，增长速率不超过每 5 秒一次， 600 年内不会产生重复号



No

Send LSUwith newer

information to source

Is seq. #higher?

No

Yes

Is seq. # the same?

Yes


database? LSA

LSU

No


Add to database

Flood LSA

Send LSAckto DR

End End



Yes

Go to A

A

No

Send LSUwith newer

information to source

Is seq. #higher?

No

Yes

Is seq. # the same?

Yes


database? LSA

LSU

No


Add to database

Flood LSA

Send LSAckto DR

End End

Point-to-Point Neighborship

– Router dynamically detects its neighboring router using the Hello protocol

– No election: Adjacency is automatic as soon as the two routers can communicate

– OSPF packets are always sent as multicast 224.0.0.5

外部网关协议•不同 AS 为什么不能用 IGP, 原因：• Internet 规模太大，使 Inter-AS 路由选择非常困难

• AS 内部的路由协议各自定义• Inter-AS 路由选择必须考虑有关策略。例如：我国国内的站点互访不应经过国外兜圈子

路由策略特点• 仅仅影响到达目标路由的下一跳• 不影响分组的目标地址，它影响用于到达目标的路径。

• 不允许数据流采用与 AS所选择路由不同的路径发往另一个 AS

• 仅仅影响数据流怎样到达 AS,不影响 AS内部路由• 可以实现任何于跳与跳范式相联系的规则• 检测源地址，所以它是在入站接口上进行配置• 内部路由优先于外部路由。

BGP 路由模型•在 BGP 接点中， BGP 路由表与 IP 路由表是分开的。

• BGP 路由表用来确定如何将路由信息发送给对等路由器。

• IP 路由表在组织上又可分为： a. AS 内部路由表。 b. 其他 AS 通告的路径

• IP 路由表用于最终的路由选择。

策略引擎 BGP 路由表

IP 路由表

BGP 运行过程•建立 AS 间的拓扑图。该拓扑图是通过各AS 的 BGP 路由器交换路由信息获得的。

•各 AS 通过邻居关系连接在一起，各个 AS之间的链路构成了所谓的树。

• BGP 按距离—矢量算法计算最短路径。• BGP 保留到每一个目的站的完整路由。

BGP Operations (Simplified)

Establish session on TCP port 179

Exchange all active routes

Exchange incremental updates

AS1

AS2

While connection is ALIVE exchangeroute UPDATE messages

BGP session

Internet Inter-AS Routing: BGP

• BGP (Border Gateway Protocol, FRC 1771): the de facto standard inter-AS routing protocol

• Path vector protocol:– Similar to distance vector protocol– Each BGP router broadcasts to neighbors (peers) entire path

(i.e, sequence of ASs) to a destination AS, but not the cost to destination

• E.g., Gateway X may send its neighbors the path to destination Z: Path (X,Z) = X,Y1,Y2,Y3,Z

• BGP distributes path info among ASs, but leaves the policy for making the route selections up to the network admin

BGP (cont’d)Suppose: gateway X sends its path to peer W• W may or may not select path offered by X

– Cost, policy (don’t route via competitors AS), loop prevention reasons.

• If W selects path advertised by X, then Path (W,Z) = W, Path (X,Z) = W,X,Y1,Y2,Y3,Z• Note: X can control incoming traffic by controlling its

route advertisements to peers:– E.g., don’t want to route traffic to Z don’t advertise

any routes to Z

BGP (cont’d)• BGP messages exchanged using TCP, port 179• BGP messages:

– OPEN: opens TCP connection to peer, identifies and authenticates itself, sent when a BGP gateway wants to first establish contact with a BGP peer

– UPDATE: advertises new path (or withdraws old path)– KEEPALIVE: keeps connection alive in absence of UPDA

TES; also ACKs OPEN message– NOTIFICATION: reports errors in previous message; also

used to close connection

Autonomous Systems (AS)

AS = set of routers and networks under the same administrationNo theoretical limit to the size of the ASAll parts within an AS remain connected.

If two networks rely on core-AS to connect, they don’t belong to a single AS

AS is identified by a 16-bit AS numberAt least one border router per AS.

This router also collects reachability information (“external routes”) and diffuses it internally and vice versa

Autonomous Systems (Continued)

• AS types: – Stub AS => only single connection to one other AS =>

it carries only local traffic.– Multihomed AS: Connected to multiple AS, but does n

ot allow transit traffic– Transit AS: carries transit traffic under policy restrictio

ns

• Traffic types: – Local = traffic originating or terminating at AS. – Transit = non-local traffic

Many Routing Processes Can Run on a Single Router

Forwarding Table

OSPFDomain

RIPDomain

BGP

OS kernel

OSPF Process

RIP Process

RIP Routing tables

OSPF Routing tables

BGP Process

BGP Routing tables

Forwarding Table Manager

IPv6

The New Internet Protocol

Outline

• The Protocol (new ICMP)• Addressing and Routing (provider addressing)• Autoconfiguration• Security• Support of Real-time Communication• Deployment Strategy

The Design of IPv6

• IPv4 design was very good IPv6 should keep most of it

• It could only increase the size of addresses and keep every thing the same

• Experience brought lessons for improvement

IPv6 Header (40 bytes)

Version Prio Flow Label

Payload Length Next Header Hop Limit

Source Address

Destination Address

0 3116

40 bytes

128 bits

128 bits

IPv4 Header (20 bytes)

Version

identification DF MF Fragment offset

Source Address

Destination Address

0 3116

20 bytes 32 bits

32 bits

Hd len ToS

Tot len

Hd chksumprotocolTTL

Options (if any)

Note that while

the IPV6 address are four times as large as the IPV4 address,

the header length is only twice as big.

Notations of IPv6 Addresses

• 128 bit is represented as:– 8 integers (16-bit) separated by colons

• each integer is represented by 4 hex digits

Example:

FEDC:BA98:7654:3210:FEDC:BA98:7664:3210

Simplifications

• Skip leading zeros– Example:1080:0000:0000:0000:0008:0800:200C:417A – is reduced to: 1080:0:0:0:8:800:200C:417A

• A set of consecutive nulls is replaced by :: (at most one :: inside an address) – the above address is reduced to:

• 1080::8:800:200C:417A

Comparison of Headers

• V6: 6 fields + 2 addr• V4: 10 fields + 2 addr + options• Deleted:

– Header length – type of service– identification, flags, fragment offset– Header Checksum

• Added:– Priority– Flow label

• Renamed:– length -> Payload length– Protocol -> Next header– time to live -> Hop Limit

• Redefined: Option mechanism

Simplifications• Fixed format headers

– no options -> no need for header length– options expressed as Extension headers

• No header checksum– reduce cost of header processing, no checksum updates at

each router– minimal risk as encapsulation of media access protocols

(e.g..., Ethernet, PPP) have checksum

• No segmentation– hosts should use path MTU discovery– otherwise use the minimum MTU (536 bytes)

Renaming

• Total Length Payload Length– not include header length– max length 64Kbytes with provision for larger packets

using “jumbo gram” option• Protocol Type Next header, can be set to:

– Protocol type (UDP,TCP, etc..)– Type of first extension header

• TTL Hop limit– “Truth in advertising!”,– number of hops NOT number of seconds

New Fields

• Flow label & Priority– to facilitate the handling of real time traffic

Options Extension Headers

Routers treats packets with options as “second class citizens” because it is slow to process, thus programmers tend not use them and options almost became obsolete.

Daisy Chain of Headers

TCP Header + Data

IPv6 HeaderNext Header=TCP

TCP Header + DataIPv6 HeaderNext Header=Routing

Routing HeaderNext Header=TCP

IPv6 extension headers

• Hop-by-hop options

• Routing

• Fragment

• Destination options

• Authentication

• Encryption Security Payload

Protocol & Header Types

Decimal Keyword Header Type0 HBH hop-by-hop3 ICMP Inet Control4 IP v4 encapsul.6 TCP17 UDP43 RH Routing hdr

Routing HeaderNext Header 0 Num addrs Next Addr

strict/loose bit mask (24)Reserved

Address[0]

Address[Num Addrs -1]

………………………...

Routers will only look at the routing header if they recognize one of their addresses in the destination field of the main header

Fragment Header• Routers do not fragment oversized packets

• Sender is to fragment &

Receiver is to reassemble

Next Header Reserved Fragment offset Res M

Identification

Destination Option Header

Will only be examined by the station

specified in the destination address.

Next Header Hdr Ext Len

Options

Option Type Opt Data Len Option Data

Hop-by-Hop Option Header

Will be examined by each router.

Has same form as destination options hdr.

194 Opt Len = 4

Jumbo Payload Length

To satisfy networking requirement of supercomputers,the Jumbo payload option is used to send very large packets (the IPv6 length field is set to zero):

ICMP…. Streamlined

• Removed unused functions in ICMP of v4

• Incorporate IGMP of v4

Type Code Checksum

Message Body

ICMP Error Messages

1 Destination Unreachable. Codes: 0 No route to destination 1 destination prohibited 3 Address unreachable 4 Port unreachable

2 Packet Too Big contain next hop MTU. used for path MTU discovery

3 Time Exceeded. Codes: 0 Hop limit exceeded 1 Fragment reassebly time exceed

4 Parameter ProblemNo error message in response to multicast or ICMP packets

Other ICMP messages128 Echo Request129 Echo Reply

130 Group Membership Query131 Group Membership Report132 Group Membership Termination

133 Router Solicitation134 Router Advertisement135 Neighbor Solicitation136 Neighbor Advertisement137 Redirect

Impact on Upper LayersUpper-layer Checksums

pseudoheader transport header transport data

Source Address

Destination Address

0 Next header Payload Length

: Mandatory (even UDP)

Domain Name Service32-bit address to 128-bit address

Programming interfaceAddress data structures AF_INET6, PF_INET6, in_addr6, sockaddr_in6

Name-to-address translation functions Address conversion functions

Points of ControversyPoints of Controversy

• Do we need more than 255 Hops?– allowing hop count to be very large, looping packets

will be relayed many times before being discarded

• Should packets be larger than 64K?– allowing very large packets increase the size of queues

and the variability of queuing delays

• Can we live without checksum?– Some IPv4 routers started to cut corners by not

verifying checksums to gain advantage over competition. By removing checksum altogether offers all routers the same advantage.

Real-time Support & Flows

• A proper handling of flows is required for high-quality multimedia communications in the new Internet

• A flow is a sequence of packets sent from a particular source to a particular (unicast or multicast) destination for which the source desires special handling by the intervening routers.

Real-time flows & Data Queues

S

R1

R2

R3

data

The flow label & source address are used to assert which packets belong to what flows

In IPv6 port numbers deep inside due to daisy chaining Even may not be visible due to encryption

SecurityIf security is provided at the IP level it

becomes standard service that all applications can use

It is absolutely necessary to implement if we want to develop of commercial use the Internet, e.g...., to deter sniffing attacks on passwords and credit card numbers.

HeadersAuthentication header

Guarantee that the source address is authentic &

the packet has not been altered during transmission.

Encryption headerGuarantee that only legitimate receivers

will be able to read the content of the packet

Transitioning the Internet

• At the beginning, all IPv6-capable hosts will also be IPv4-capable so as to retain connectivity with the existing Internet.

• To transform IPv4 into a dual-stack IPv6-capable host, it should include:– The IPv6 basic code– Handling IPv6 within TCP & UDP– Modify socket interface to support new addresses– Handling the interface with the name service

The 6-Bone• The Similar to the M-Bone, Initially the

connectivity is achieved by tunneling

• IPv6 packet will be encapsulated within IPv4 packets.

IPv6 domain

IPv6 domain

R R

IPv4 onlyNetwork

RIP ( Routing Information Protocol) RFC 1058 and 1723 Included in BSD UNIX in 1982 Distance vector algorithm Distance metric: number of hops (max = 15.

Documents

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routes slide

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authentication slide

b s metric