Rip ( Routing information protocol)
characteristics of RIP
• RIP supports IP and IPX routing.
• RIP utilizes UDP port 520
• RIP routes have an administrative distance of 120.
• RIP has a maximum hopcount of 15 hops.
Any network that is 16 hops away or more is considered unreachable to RIP, thus the maximum diameter of the network is 15 hops. A metric of 16 hops in RIP is considered a poison route or infinity metric.
RIP Versions
RIP has two versions, Version 1 (RIPv1) and Version 2 (RIPv2). RIPv1 (RFC 1058) is classful, and thus does not include the subnet mask with its routing table updates. Because of this, RIPv1 does not support Variable Length Subnet Masks (VLSMs). When using RIPv1, networks must be contiguous, and subnets of a major network must be configured with identical subnet masks. Otherwise, route table inconsistencies (or worse) will occur. RIPv1 sends updates as broadcasts to address 255.255.255.255. RIPv2 (RFC 2543) is classless, and thus does include the subnet mask with its routing table updates. RIPv2 fully supports VLSMs, allowing discontiguous networks and varying subnet masks to exist.
RIPv2
• Routing updates are sent via multicast, using address 224.0.0.9
• Encrypted authentication can be configured between RIPv2 routers
RIPv2 can interoperate with RIPv1
• RIPv1 routers will sent only Version 1 packets
• RIPv1 routers will receive both Version 1 and 2 updates
• RIPv2 routers will both send and receive only Version 2 updates
RIP Timers
hello- 30 sec
invalid time-180 sec
hold down time - 180- sec
flush time- 240 sec
To configure the RIP timers:
Router(config)# router rip
Router(config-router)# timers basic 20 120 120 160
Split-Horizon – Prevents a routing update from being sent out the interface it was received on.
Route-Poisoning – Works in conjunction with split-horizon, by triggering an automatic update for the failed network, without waiting for the update timer to expire. This update is sent out all interfaces with an infinity metric( 16 hops count ) for that network.
RIP Passive Interfaces and configuration
RouterC(config)# router rip
RouterC(config-router)# network 10.4.0.0
RouterC(config-router)# network 10.2.0.0
RouterC(config-router)# passive-interface s0 ( s0 means serail interface )
RouterC(config)# router rip
RouterC(config-router)# network 10.4.0.0
RouterC(config-router)# network 10.2.0.0
RouterC(config-router)# passive-interface default
RouterC(config-router)# no passive-interface e0
RIPv2 Authentication
RouterA(config)# key chain MYCHAIN
RouterA(config-keychain)# key 1
RouterA(config-keychain-key)# key-string MYPASSWORD
RouterB(config)# key chain MYCHAIN
RouterB(config-keychain)# key 1
RouterB(config-keychain-key)# key-string MYPASSWORD
characteristics of RIP
• RIP supports IP and IPX routing.
• RIP utilizes UDP port 520
• RIP routes have an administrative distance of 120.
• RIP has a maximum hopcount of 15 hops.
Any network that is 16 hops away or more is considered unreachable to RIP, thus the maximum diameter of the network is 15 hops. A metric of 16 hops in RIP is considered a poison route or infinity metric.
RIP Versions
RIP has two versions, Version 1 (RIPv1) and Version 2 (RIPv2). RIPv1 (RFC 1058) is classful, and thus does not include the subnet mask with its routing table updates. Because of this, RIPv1 does not support Variable Length Subnet Masks (VLSMs). When using RIPv1, networks must be contiguous, and subnets of a major network must be configured with identical subnet masks. Otherwise, route table inconsistencies (or worse) will occur. RIPv1 sends updates as broadcasts to address 255.255.255.255. RIPv2 (RFC 2543) is classless, and thus does include the subnet mask with its routing table updates. RIPv2 fully supports VLSMs, allowing discontiguous networks and varying subnet masks to exist.
RIPv2
• Routing updates are sent via multicast, using address 224.0.0.9
• Encrypted authentication can be configured between RIPv2 routers
RIPv2 can interoperate with RIPv1
• RIPv1 routers will sent only Version 1 packets
• RIPv1 routers will receive both Version 1 and 2 updates
• RIPv2 routers will both send and receive only Version 2 updates
RIP Timers
hello- 30 sec
invalid time-180 sec
hold down time - 180- sec
flush time- 240 sec
To configure the RIP timers:
Router(config)# router rip
Router(config-router)# timers basic 20 120 120 160
Split-Horizon – Prevents a routing update from being sent out the interface it was received on.
Route-Poisoning – Works in conjunction with split-horizon, by triggering an automatic update for the failed network, without waiting for the update timer to expire. This update is sent out all interfaces with an infinity metric( 16 hops count ) for that network.
RIP Passive Interfaces and configuration
RouterC(config)# router rip
RouterC(config-router)# network 10.4.0.0
RouterC(config-router)# network 10.2.0.0
RouterC(config-router)# passive-interface s0 ( s0 means serail interface )
RouterC(config)# router rip
RouterC(config-router)# network 10.4.0.0
RouterC(config-router)# network 10.2.0.0
RouterC(config-router)# passive-interface default
RouterC(config-router)# no passive-interface e0
RIPv2 Authentication
RouterA(config)# key chain MYCHAIN
RouterA(config-keychain)# key 1
RouterA(config-keychain-key)# key-string MYPASSWORD
RouterB(config)# key chain MYCHAIN
RouterB(config-keychain)# key 1
RouterB(config-keychain-key)# key-string MYPASSWORD
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