RIP & EIGRP
Day 25
RIP
RIP (Routing Information Protocol) uses hop count as its metric. The maximum hop count is 15. It is not usually used in real networks. It has three versions:
RIPv1 and RIPv2 - used for IPv4
RIPng (RIP Next Generation) - used for IPv6
It uses two message types:
Request - to ask neighbours to send their routing table
Response - to send the local router's routing table to neighbouring routers
By default, routing tables are shared every 30 seconds.
Versions
RIPv1:
only advertises classful addresses
doesn't include subnet mask information
doesn't support VLSM, CIDR
messages are broadcast to
255.255.255.255
RIPv2:
supports VLSM, CIDR
includes subnet mask information
messages are multicast to
224.0.0.9
Configuration
First, enter the RIP config mode, using the command router rip from the global config mode. Choose a version with the command version followed by the version number. To disable classful networking logic use the command no auto-summary. Then you have to use the network command. The network command tells the router to:
look for an interface with an IP address that is in the specified range
activate RIP on the interfaces that fall in the range
form adjacencies with connected RIP neighbours
advertise the network prefix of the interface
If there are no RIP neighbours connected to the interface, the interface should be configured as a passive interface so that the router doesn't send RIP advertisements out of the interface. To do so, use the command passive interface followed by the interface number. The command is entered from the RIP config mode. To advertise the default route via RIP, use the command default-information originate. To check the information on the routing protocol being used, enter the command show ip protocols from the privileged EXEC mode.
EIGRP
EIGRP (Enhanced Interior Gateway Routing Protocol) is a Cisco proprietary protocol that is considered an advanced distance vector routing protocol. It is much faster than RIP and doesn't have a 15 hop-count limit. It sends messages using a multicast address 224.0.0.10. By default, it load-balances like RIP over 4 paths but it is the only IGP that can perform unequal-cost load-balancing.
Configuration
To enter the EIGRP config mode, use the command router eigrp followed by the AS number. The AS (Autonomous System) number must match between the routers to form an adjacency. Auto-summary and passive-interface configurations are the same as in RIP. The network command assumes a classful address if the network mask is not specified. EIGRP uses a wildcard mask instead of a regular subnet mask. A wildcard mask is just an inverted subnet mask. All 1s in the subnet mask are 0 (zero) in the equivalent wildcard mask and vice versa.
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