1

Lesson 5 Internet Protocol

Objectives :

Understanding connection-less type network architecture,

protocol and system. TCP-IP or Internet is typical connection-

less network. Basic protocols such as signaling and routing are

described.

2Fig.4.1

IP header

HeaderLengthVersion TOS Length

Identification(13 bit)

Fragment offset

TTL Protocol Checksum

Source address

Destination address

(3 bit)Flag

(4 bit) (4 bit)

Structure of IP header

IP header is used for network layer function. Packet transmission is its function.

Destination and Source address are written on the header.

3

IP address

11000001

11111111

Prefix

Mask

193.60.96.0/20193 60 96 0

255 255 240 0

prefix/mask length

255.255.255.255

D E

0.0.0.0

193.60.96.0/20193.60.0.0/16

00111100 01100000 00000000

11111111 11110000 00000000

0.0.0.0 255.255.255.255

A B C D E

Unicast

128 nets 16,384 nets 2,097,152 nets CIDR

Fig.4.2

IP address and CIDR

CIDR TECHNOLOGY → Multiple IP addresses are integrated into a single routing table.

1. The addresses share the same bits from the top of the IP address with the same bit pattern

(this is called a “prefix”).

2. The routing table 32-bit address and the 32-bit mask.

3. The routing protocol is expanded so that it can handle the 32-bit addresses and 32-bit

masks that have been introduced.

4Fig.4.3

Prefix NHR

IP forwarding table

IP header

DA=148.32.96.4148.32.0.0/16148.32.96.0/24

140.252.13.0/24129.60.0.0/16

129.60. 225.0/24 EBA

AB

224.0.0.0/16 D

Concept of “Longest prefix matching” search and the forwarding table.

Using CIDR technology, routing table becomes small. Longest prefix matching is used for packet forwarding.

5

Prefix/mask length Next hop Output port

129.66/16 129.30.166.55 3

129.66.103/24 129.30.167.13 4

176/8 129.30.168.20 6

176.10/16 129.30.169.21 5

176.10.25/24 129.30.170.169 1

Example of routing table

Table.7.2

6Fig.7.24

b d

c e g

a

f

Prefixa: 00＊b: 0001＊c: 001＊d: 0101＊e: 101＊f: 10100＊g: 111＊

0 1

0 1

0 1 0

1 1

0 1

0 1

0

1

0

1st bit

2nd bit

3rd bit

4th bit

5th bit

6th bit

101011

Trie structure

図5.4

7Fig.7.25

fb c

a d e g

Prefixa: 00＊b: 0001＊c: 001＊d: 0101＊e: 101＊f: 10100＊g: 111＊

0 1

0 101

01 1

01 11

00

Patricia tree

図5.5

8Fig.7.26

100000

101000

101010

101011

101111

111111

10101*101*1*

101101Destination address

Step-1

Step-2

Step-3

Binary search method

9Fig.7.27

Input dataOutput data（Result x）

Logic ciru

it

Entry

比較回路

比較回路

比較回路

比較回路

結果1

結果2

結果3

結果4

Reference data

Reference data

Reference data

Reference data

Comparison circuit

Comparison circuit

Comparison circuit

Comparison circuit

Result-1

Result-2

Result-3

Result-4

Typical structure of route lookup system using CAM

10Fig.7.28

129.66/16

比較回路

129.66.103/24

比較回路

比較回路

比較回路

Priority en

coder

Destination IP address

(129.66.34.40)

Output port(3)

176.10.25/24

176/8

#1

#4

#3

#6

Prefix Mask length Output port

Mask len

gth

is descen

din

g ord

er

Comparison circuit

Comparison circuit

Comparison circuit

Comparison circuit

Ternary CAM (TCAM)

11

Packet format using Ethernet header and TCP-IP header (Review)

Data

TCP header

IP header

Ethernet header

User data

Transport layer

Network layer

Data link layer

This lesson is focused on this part.

Fig.2.15

12Fig.2.16

31161040

Code BitReserved

Urgent Pointer

Window

Option

DEST PORT (destination port number)

DATA

Checksum

HLEN(header length)

ACK (acknowledgment number)

SEQ (source sequence number)

SRC PORT (source port number)

TCPheader

FIN

SYN

RST

PSH

ACK

URG

Structure of TCP header (Review)

For rate control

Port number

TCP header is used for transport layer functions. Reliable transmission, flow control and error recovery are functions.

13Fig.4.4

AS2

AS3EGP

IGPAS1

IGP and EGP（Inside-AS routing and Inter-AS routing）

Interior Gateway Protocol Exterior Gateway protocol

14Ｔable 4.1

Type Outline Example

Distance vector Seeks the next hop in the shortest route by exchanging a distance vector table (includes destination address information, etc). Bellman-Ford algorithm is used.

RIP, IGRP

Path vector Selects the route with the shortest path length that is possible to avoid a routing loop by exchanging a path vector (includes through node information to destination address, etc.)

BGP

Link state Each node has topology information by exchanging a link state and calculates the shortest route by using topology information.

OSPFIS-IS

Categorization and operation principle of routing protocol (Overview)

15Fig.4.5

Distance vector type

5276

BC

AD

Distance

Next hopDestination

B

X C

A

Only next hop router and distance to the destination are listed.

D

16Fig. 4.11

Destination=APath=D-B-A

E

F

A

B

D

C

Path vector type protocol

Set of destination and path is listed.

Path = D－B－A is the shortest path from F to A.

17Fig. 4.15

A

32

1

1

3

5

4

1

B

Source

F

1

3

Link state type routing protocol

C

E

D

Distance information from source to all nodes are calculated. This “Map” is called “Link state”.

18Table 4.2

Distance vector table (Distance vector type)

Destination Next hop Distance

129.60. 225.0/24148.32.0.0/16148.32.96.0/24224.0.0.0/16140.252.13.0/24129.60.0.0/16

EBADAB

3327

2910350

19

Concept of operation of distance vector type routing protocol

50BA

Distance

Next hopDestination

52101

BC

AA

Distance

Next hopDestination

100CA

Distance

Next hopDestination

B

X C1

2

A

Select this

50

100

Only next hop router (NHR) and distance are known.

Fig.4.5

20Fig.4.6

Bellman’s formula

i

j

D(t,i)

d(i,j)

D(t,j)

Destination

SourceD(t+1,i) = min(D(t,i), d(i,j)+D(t,j))

Shortest distance from source to destination can be determined by Bellman’s formula. It selects shorter path among alternative routes.

21Fig.4.7

ABC

Src. Dst.A (0,A) (0,A) (0,A) (0,A) (0,A) (0,A) (0,A)B (1,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B)C (2,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B)A (1,A) (Inf,A) (3,C) (3,C) (5,C) (5,C) (7,C)B (0,B) (0,B) (0,B) (0,B) (0,B) (0,B) (0,B)C (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C)A (2,B) (2,B) (2,B) (4,B) (4,B) (6,B) (6,B)B (1,B) (1,B) (1,B) (1,B) (1,B) (1,B) (1,B)C (0,C) (0,C) (0,C) (0,C) (0,C) (0,C) (0,C)

(dist,nh)

5 6Time 1 2 3 4

A

B

C

0Detect link down

Counting to Infinity problem

22Fig. 4.8

ABC

Src. Dst.A (0,A) (0,A) (0,A) (0,A) (0,A) (0,A) (0,A)B (1,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B)C (2,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B)A (1,A) (Inf,A) (Inf,C) (Inf,C) (Inf,C) (Inf,C) (Inf,C)B (0,B) (0,B) (0,B) (0,B) (0,B) (0,B) (0,B)C (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C)A (2,B) (2,B ) (2,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B)B (1,B) (1,B) (1,B) (1,B) (1,B) (1,B) (1,B)C (0,C) (0,C) (0,C) (0,C) (0,C) (0,C) (0,C)

(dist,nh)

A

B

C

0 5 6Time 1 2 3 4Detect link down

Poison-reverse

Split horizon/Poison reverse method

23Fig. 4.9

Src. Dst.

A (0,A) (0,A) (0,A) (0,A) (0,A) (0,A) (0,A) (0,A) (0,A) (0,A)B (1,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B)C (2,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B)D (2,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B) (Inf,B)A (1,A) (Inf,A) (Inf,A) (Inf,A) (4,C) (4,C ) (4,C) (7,C) (7,C ) (7,C)B (0,B) (0,B) (0,B) (0,B) (0,B) (0,B) (0,B) (0,B) (0,B) (0,B)C (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C)D (1,D) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C)A (2,B) (2,B) (3,D) (3,D) (3,D) (3,D) (6,D) (6,D) (6,D) (9,D)B (1,B) (1,B) (1,B) (1,B) (1,B) (1,B) (1,B) (1,B) (1,B) (1,B)C (0,C) (0,C) (0,C) (0,C) (0,C) (0,C) (0,C) (0,C) (0,C) (0,C)D (1,D) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C)A (2,B) (2,B) (2,B) (Inf,B) (Inf,B) (5,B) (5,B ) (5,B) (8,B) (8,B)B (1,B) (1,B) (1,B) (1,B) (1,B) (1,B) (1,B) (1,B) (1,B) (1,B)C (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C) (1,C)

D (0,D) (0,D) (0,D) (0,D) (0,D) (0,D) (0,D) (0,D) (0,D) (0,D)

(dist,nh)

A

C

D

0

B

5 9Time 1 2 3 4 6 87

ABC

D

Detect link down

Problem of Split horizon/Poison reverse

24

Path vector type protocol

Destination=APath=D-B-A

Destination=APath=E-B-A

Destination=APath=E-C-A

E

F

A

B

D

C

Fig.4.11

25Fig. 4.12

A

Link state L

Flooding

C E

A

B D

Concept of link state and “Flooding”

Link state information is flooding to all the nodes. Each link state table is updated by this flooding information.

26Fig. 4.15

Link state type routing protocol

1

32

1 A

1

3

5

4

1

C

B

D

dji=1

2Dj

Destination node

Q

Calculates Dj=min(Dj,dij+Di) for node-j.Determines the group of nodes Q that Dj becomes minimum.Remove it from Q

A=1 determinedRest nodes: B,C,DB=min(3,1+1)=2 → this is the smallestC=min(4,5+1)=4D=min(3,2+1)=3B=2 determined

F

1

3

E

Shortest path is found by “Dijkustra’s algorithm”

27Fig. 4.16

Example of advertising the link state

(b) Example of network LSA

D B

AC

A BLink state of router-B

A D CLink state of router-B

A BLink state of router-CB D C

Link state of router-A

D

B

A

C

Network aa

Link state of router-A

ABCD

(a) Example of router LSA

Abstracted information into one Network LSA.

28

Flooding between areas

Fig. 4.17

C

E

A

B

D

C1 C2

C3 C4C5

C6

Area 0.0.0.2

Area 0.0.0.0 (Backbone)

Area 0.0.0.1

Summary-LSA by D- prefix = A- cost = min(C1+C3, C2+C5)

Summary-LSA by C- prefix = A- cost = C2

Summary-LSA by E- prefix = A- cost = min(C1+C4, C2+C6)

Summary-LSA by B- prefix = A- cost = C1

29

Structure of LSA header

0 1 2 30 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| LS age | Options | LS type |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Link State ID |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Advertising Router |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| LS sequence number |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| LS checksum | length |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Elapsed time from LSA occurred (0～30 min)

Currently used when OSPF Hello Database Description Indicates LSA type (Note)

Independent numeric value

Sequential number

LSA header+container value(1～65535 byte)

LSA originatingrouter ID

LSA Type=1 Router LSAType=2 Network LSAType=3 Summary LSAType=4 ASBR Summary LSAType=5 AS-External LSA

Fig. 4.18

(Note)

30

Structure of Router-LSA(Type-1, for routers connected by point-to-point)

0 1 2 30 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| LS age | Options | 1 |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Link State ID |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Advertising Router |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| LS sequence number |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| LS checksum | length |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| 0 |V|E|B| 0 | # links |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Link ID |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Link Data |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Type | # TOS | metric |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| |

... | |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Type | # TOS | TOS metric |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Link ID |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Link Data |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| ... |

Enter the same values

ＬＳ Type=1

LSA originating router’s ID

Number of links from router

Metrics(specified with 0～65535)

Link 1

Link i

Router TypeFor example,neighboring router’s ID

Link Type(Point-to-point,Transit, Stub, Virtual link)

FlagV: VirtualE: ASBRB: ABR

Fig. 4.19(Origin) Link1 (Destination)

31

What is the metric?

Metric examples (0～65535)

1. Number of router hops (7hops)2. Distance (km)3. Number of wavelength (32 wavelength)4. Link bandwidth (1Gb/s)5. Bandwidth utilization (20%)6. Wavelength utilization / vacant number of

wavelength･･･

32

Structure of Network-LSA

Fig. 4.20

0 1 2 30 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| LS age | Options | 2 |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Link State ID |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Advertising Router |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| LS sequence number |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| LS checksum | length |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Network Mask |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Attached Router |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| ... |

Enter value of DR(A)

Specify subnet mask

Enter all the routers within subnet

(A, B, C, D)

DR : Distinguished Router

ABCD

Networkα B C

DADR

33

Summary-LSA from router-A to Arena X

Fig. 4.21

0 1 2 30 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| LS age | Options | 3 |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Link State ID |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Advertising Router |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| LS sequence number |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| LS checksum | length |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Network Mask |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| 0 | metric |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| ... |

LS Type=3 : Summary LSA

ID of router-B

Metric(C1)

ID of router-A

Mask of Area A(0.0. 0.1)

TOS=0=normal service BSummary LSA

A

C1

Area0.0.0.1

34

Concept of operation of BGP-4 （Path vector type protocol and loop detection）

Fig. 4.25

AS1

AS2AS3

10.1.1.1via AS4

10.1.1.1via AS3-AS4

10.1.1.1via AS1-AS3-AS4

10.1.1.1via AS2-AS1-AS3-AS4

IBGP

EBGP

AS4

35

Border router (BGP speaker) and BGP session

Fig. 4.26

AS1

AS2 AS3

Border router

BGP session

EBGP

IBGP

：BGP speaker：Non BGP speaker

36Fig. 4.32

Routing control of Outbound traffic using Local Ｐref attribute

R12R11

AS1

IBGP

AS4

AS2 AS3

128.213.0.0/16 128.213.0.0/16c

(Set local pref to 200)

(Set local pref to 300)

>128.213.0.0/16-- 300128.213.0.0/16-- 200

Select the route having a larger value of local pref

128.213.0.0/16

(AS1 to AS4 traffic control)

Select larger local pref value. It can create traffic control.

37Fig. 4.33

R2

R12R11

MED = 120

MED = 200

128.213.0.0/16

AS2

AS1

Use smaller MED as a speaker

Routing control of Inbound traffic using MED attribute (AS2→AS1 access control)

Please use R11 for boarder

38Fig. 4.36

EBGP

IBGPLearn routes

Don’t learn routes

IBGP is full meshed within AS

Never hops over multiple IBGP

Rule of advertising via IBGP session and EBGP session

In AS, each BGP router are connected with mesh topology.

39Fig. 4.37

Scalability

EBGP

Full mesh2

)1( NN

IBGP mesh

40Fig. 4.38

EBGPIBGP

AS1

AS2

AS3

RR

RR-Client

ＲＲ

RR-client

Route reflector

41Fig. 4.39

Sub-AS10Sub-AS12

Sub-AS11

AS confederation 1

AS2

AS3

EBGP

EIBGP

IBGP

Confederation

The AS is divided into multiple SubAS, and each SubAS functions like a single AS.

42

Conclusions for Lesson 5

To understanding connection-less protocol,detail IP networking issues were studied. ICPIP packet structure and functions wereintroduced. Basic routing protocols were alsoshown in this session.