2011 MTSC Dynamic Routing

flutteringevergreenNetworking and Communications

Oct 29, 2013 (3 years and 11 months ago)

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2011 MTSC

Dynamic Routing

Prepared by: Moxa Net TS

Date: dd
-
mm
-
yyyy

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Agenda


RIP


RIP on Moxa L3 switches


OSPF


OSPF basic concepts


OSPF settings on Moxa L3 switches


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RIP

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Dynamic Route


RIP


Routing Information Protocol


Distance Vector routing protocol.


Uses “Hop Count” as the metric.


Routing table exchanged between adjacent routers:


Periodically (30 sec.)


Routing path changes


Selects the “Best Route (Lowest metric value)” routing path.


3 versions of RIP


RIPV1, RIPV1c, RIPV2

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RIP in
Moxa

L3 switches

Supports V1, V1c & V2

Routing entry update to
neighbors

Enable RIP in each
interface

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A

B

RIP routing entry

192.168.2.100

192.168.2.200

192.168.1.100

192.168.3.200

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OSPF

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OSPF


Open Shortest Path First.


Link State routing protocol.


Hello packet creates neighbor relation


LSA (Link State Advertisement) exchanges
topology information


Dijkstra algorithm finds the shortest path

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Link State Advertisement


Define the relationship to neighbor routers


Learn from Hello packets


Each router has its own LSA

a

b

c

d

e

f

10

20

20

20

10

10

30

Router a

Neighbor

metric

b

10

d

20

Router e

Neighbor

metric

b

20

d

20

f

10

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Link State database


The Link state database of an area


Flood to all routers


Share by all routers


Used to find the shortest path

a

b

c

d

e

f

10

20

20

20

10

10

30

Shared by all routers

a

b

c

d

e

f

b10

a10

b10

a20

b20

c30

d20

e20

f30

e20

d20

e10

c10

f10

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Shortest path


Dijkstra algorithm


Loop free tree


Each router has its own SPF








How are SPF formatted on each router?

a

b

c

d

e

f

10

20

20

20

10

10

30

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Shortest path

a

b

c

d

e

f

10

20

20

20

10

10

30

a

(0)

SFP from router a

b

(10)

d

(20)

e

(30)

c

(20)

f

(40)

SFP from router e

e

(0)

f

(10)

d

(20)

a

(30)

b

(20)

e

(40)

Each router has its own SPF!!!

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Areas of OSPF


The network is divided into areas
hierarchically


Suitable for larger networks


More routing efficiency


Each Area maintains its own Link State
database


Backbone area (Area 0) is must

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Autonomous System















Autonomous System







Area 2






Area 3






Area 1

Area 0





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L3 OSPF Network

A

B

H

F

G

J

I

K

E

C

D

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Different types of LSA


Link State Advertisement


Update link status between adjacent routers/area


Router LSA (Type 1)


By all routers within an Area (router <
-
> router)


Network LSA (Type 2)


By Designated Router (DR
-
> routers)


Summary LSA (Type 3 & 4)


By ABR (area <
-
> area)


External LSA (Type 5)


By ASBR (AS <
-
> AS)

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Area Y








Area X

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Routers in the Area

ABR

DR/BDR

Router/Network LSA

Summary LSA
















AS

External LSA

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OSPF settings on
Moxa

L3 switches

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OSPF Settings


Router ID= Current Router ID


The identification of the router


Format= xxx.xxx.xxx.xxx


IP address


One Router= One Router ID


No duplicate Router IDs on L3 switches, even across
areas



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OSPF Settings


Redistribute


The router will distribute a routing entry to an OSPF
Area.


Connected


Direct connect routing entry will be updated to neighbors
the router


Static Router


Static routing entry will be updated to neighbors


RIP


RIP routing entry will be updated to neighbors


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OSPF Area Settings


Set up the router Area

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OSPF Area Setting


Set up the area the router belongs to


Area ID


0.0.0.0 to 255.255.255.255


0.0.0.0= Backbone Area


A router can belong to multiple areas


Area Type


Normal Area, Stub Area, NSSA



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Area 2






Area 1

Area 0





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L3 Network

A

B

D

I

E

C

G

Area ID= 0.0.0.0

Router ID= 0.0.0.1

Area ID=

0.0.0.0

0.0.0.1

Router ID= 0.0.0.2

Area ID= 0.0.0.2

Router ID= 0.0.0.3



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OSPF Interface Settings

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OSPF Interface settings


Hello packet


Exchanged between routers to discover neighbors.


Router Priority


Used to elect DR


Router with bigger number has higher priority to be DR


Hello/Dead Interval


Configure time interval between Hello packets


If Hello is not seen after Dead interval, the router
declare the neighbor is down.


Authentication


MD5 or Simple (plain text)

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OSPF Interface settings


Authentication setup


By interfaces


Same setting on adjacent routers

Type: MD5

Auth. Key: xxxyyy

Auth. ID: 1


Type: MD5

Auth. Key: aaabbb

Auth. ID: 2


Interface 1

Interface 2

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Area 1.1.1.1





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A

B

C

OSPF Neighbor Table

Router ID

172.25.1.69

Router ID

172.25.1.61

172.25.1.66

172.25.1.61

172.25.1.65

172.25.1.62

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OSPF Database Table

From this database, we understand…


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OSPF database


The area is 0.0.0.11…




The area has 4 routers…




The area has 4 networks…




Router 172.25.1.61 is ABR…

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Routing Table

Local & direct
connect interfaces

Learned by OSPF

Learned by RIP

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RIP V.S. OSPF

OSPF

RIP

Link State protocol

Distance Vector protocol

No hop count limit

15 hop count limit

Routing info are exchanged
between neighbor routers

Routing info broadcasted
within the network

Routing info updates only
when routing changes.

Routing info updates
periodically & routing changes

Suitable for larger network

Suitable for smaller network

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Q & A

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Q & A