CCNA learning: Routing Protocol

Routing Protocol (Router table which define the route path): RIP / BGP / IGRP

Routed Protocol: IP / IPX

Route Table

Network Protocol      Destination Network       Exit Interface

Connected                   10.120.2.0                           E0

RIP                                172.16.1.0                           S0

IGRP                              172.17.3.0                           S1

Routing Protocol works in Transport Layer or Application Layer, define the path

Routed Protocol works in Network Layer, follow the path which defined by routing protocol to encapsulation records

One router must contain one route table.

Route require information:

Source address/Destination address/Possible path/Best path/Administrative distance

Administrative distances: the reliable in different route protocols

Reliable range: 0 - 255

0: highest

255: lowest

Reliable: Connected 0 < Static Route 1 < EIGRP 90 < IGRP 100 < OSPF 110 < RIP 120

Routing Protocol Type

Static Route: User manually define --> small and intermediate scope network, no extend plan

Static route setting: (config)#ip route network mask (address | interface) [administrator distance] [permanent]

Example:

(config)#ip route 172.16.1.0 255.255.255.0 172.16.2.1

(config)#ip route 192.168.5.0 255.255.255.0 172.16.2.2

Static route delete: (config)#no ip route network mask (address | interface) [administrator distance] [permanent] 

Example:

(config)#no ip route 172.16.1.0 255.255.255.0 172.16.2.1

Advantages:

1. save cost

2. save bandwidth

3. increase security

Disadvantages:

1. Network administrator need to know the total topo structure

2. When topo structure change, network administrator need to change manually

3. Not suitable for large network

Floating static route: change the administrator distance for protocol instead of using the default administrator distance

Default route: this will be used when there is no route information

Default route used for internet, not security

Default route setting: (config)#ip route 0.0.0.0 0.0.0.0 172.16.2.2

Dynamic Route: Routing Protocol will be adjusted automatically by flow volumn or network structure --> large scope network

Dynamic route protocol type:

1. Distance vector(routing by rumour): RIPv1, RIPv2, IGRP

2. Link state: OSPF IS-IS

3. Hybrid: EIGRP, BGP(Path Vector)

Distance Vector

Distance: how far

Vector: In which direction

Occasionally or regular send broadcast signals of route table to other routers, to calculate the distance, update information into route table in each router --> compare with static router add cost

Convergence time: the time start with network topo change, until all the router update the route table. During the time, all the package can not be transported.

Route loop: when one subnet got problem, the router update route table update according to other router, not the actural situation. The distance will be increased to  infinity.

Solution for route loop

1. Split Horizon: The information which is send by one router will not be accepted by itself.

2. Route Poisoning: When found subnet broken, set the distance to infinity and broadcast to others

3. Holddown Timers: When found subnet broken, set the subnet is down and broadcast to others. During holddown time, the subnet recover, the table will updated.

4. Triggered Updateds: Not use regular update. Only when topo update, route give out the update to others.

5. Max-hop: set max value of hop, when reach the max value, the distance will not be increased.

RIP Route Information Protocol

IGRP (cisco route protocol) used in large network, default max hop 100

RIPv1 Characters:

1. Hop(metric) to calculate the distance, Maz hop is 16

2. Router broadcast update information every 30 seconds

3. Max support 6 paths which have same hop(metric) to do load balance

4. Support CLASS, Not support VLSM, No need subnet mask

5. Not support authentication

RIPv2 Characters:

1. No class, support VLSM

2. Router multicast(224.0.0.9), not broadcast

3. Support authentication, support MD5

4. Support manually summary

RIP Port: UDP 520

RIP Information Type:

1. Request message: request for update

2. Response message: requested update

RIP Work Process:

The interface of router which start the RIP will broadcast the request messages to others, then start to wait for the feedback. The neighbor receive the request message will send response message to the interface of router

RIP Work Frequency: 30 seconds

RIP config:

Start RIP:

(config)#router rip

(config-router)#network <network-number>

network-number: Class A, B, C

Example:

Check protocol status:  #sh ip protocols

Check router table: #sh ip router

Check router table with related protocol: #sh ip router rip

RIPv2 config

(config)#router rip

(config-router)#version 2

(config-router)#network <network-number>

network-number: Class A, B, C

EIGRP

EIGRP(Enhanced IGRP): only can be used by cisco products

EIGRP support IP / IPX / Apple Talk

EIGRP: (balance hybrid routing)

1. choose best pths based on bandwidth and delay by default,

2. converge rapidly

Balance hybrid routing: share attibutes of both distance vector and link-state routing

Disadvantages:

1. only can be used by Cisco.

2. when used in WAN, router will be stuck in active(SIA) status for long time.

EIGRP Characters:

1. Update of router table frequency unregularly. When topo change or metric(hop) standard change, partly update router table

2. Update information including subnet mask(Classless), support VLSM, support unconnect subnet

3. Follow the information of IGRP

EIGRP has three tables: Neighbor Table; Topology Table; Routing Table

Neighbor Table(by hellow package, every 5 seconds, 60 seconds dead interval): Next-hop Router, Interface

Topology Table: Destination 1, Successor(best path); Destination 1 Feasible Successor(Useful path)

Routing Table: Destination 1, Successor

When Best path got problem, it will use useful path to instead of best path --> Save convergence time

IGRP vs EIGRP

Same:

1. metric calculation

IGRP: Metric=BW(min)+DLY(sum)

EIGRP: Metric=256*[BW(min)+DLY(sum)]

2. Support load balance on same metric or different metric

Difference:

1. EIGRP support VLSM, unconnect subnet

2. EIGRP support summary manually

3. EIGRP converge rapidly

4. EIGRP update only when change

EIGRP config

Start EIGRP:

(config)#router eigrp {Autonomous System-number}

(config-router)#network {network-number}

Example

Verify EIGRP:

Check Neighor Information: (config)#sh ip eigrp neighbors

Check topo information: (config)#sh ip eigrp topology

Check routing table information: (config)#sh ip route eigrp

Check protocol: (config)#show ip protocols

Check traffic: (config)#show ip eigrp traffic

OSPF

OSPF: Open Shortest Pass First

Advantage:

1. Rapidly response to network change

2. Triggered update when network change

3. Support VLSM

4. Easily manage

Trace the link state:

1. Neighbr information

2. All router in area

3. Best path to target network

OSPF has three tables:

1. neighbr table(send hello package, default every 10 seconds, 40 seconds dead interval, in same area): neighbr router information

2. topology table: link state database (LSDB)

3. routing table: best path

OSPF Area Type:

1. Backbone Area --> Area 0

2. Area --> Area 1, Area 2, ....

All area should connect with backbone area

OSPF packages:

1. Hello

2. Database Description(DBD)

3. Link-State Request

4. Link-State Update

5. Link-State Acknowledgement

RID(Router ID)

1. Router symbol

2. Choose max IP address in logical port or max IP address in physical ports

OSPF DR / BDR

DR:     the manage router

BDR:   ther backup of manage router

DROTHER: the left routers

Choose DR / BDR: priority

Default: all router's priority is 1

Compare the RID of router, the top RID is DR, the second RID is BDR

Network Administrator may change priority manually

(config-if)#ip ospf cost {priority}

priority: 0 - 255

When network change, Router will send message to 224.0.0.6, DR/BDR receive the message from 224.0.0.6; Then DR/BDR use 224.0.0.5 to other DROTHERS, DROTHERS receive messge from 224.0.0.5

OSPF LSDB/LSA Process

OSPF neighbr relation establish process:

1. Down state --> start the OSPF protocol

2. Init state --> Router A send out hello information, Router B receive hello information, Router B send out hello information out, Router A receive.

3. Two Way state

4. Exstart State: find out who is DR

5. Exchange State: exchange DBD information and send LSAck messages to confirm receive.

6. Loading State: exchange the topo information

7. Full State: Establish Neighbr Connection

OSPF config

Start OSPF:

(config)#router ospf <process-id>

(config-router)#network <address> <wild card bits> area area-id

Router A:

(config)#router ospf 1

(config-router)#network 172.16.1.1 0.0.0.0 area 0

(config-router)#network 10.0.0.0 0.255.255.255 area 0

Router B: (could be updated to below)

(config)#router ospf 2

(config-router)#network 10.0.0.0 0.255.255.255 area 0

Check protocol: #sh ip protocols

Check Routing table: #sh ip route

Check OSPF area: #sh ip ospf interface

Check neighbor: #sh ip ospf neighbor