RIP
Information Protocol the Routing , genus IGP protocol is (sent directly routing protocol is a distance-vector protocol) distance vector type dynamic routing protocol, using UDP protocol, port number 520 .
Bellman Ford algorithm
RIPv1
l There are categories of routing protocol, routing information does not carry the mask, it does not support VLSM and CIDR
l broadcast ( 255.255.255.255 send a message form), and does not support authentication
l automatically aggregated routing information, and a summary can not be closed automatically
RIPv2
l classless routing protocol, routing information to carry subnet mask, support VLSM , CIDR
l multicast ( 224.0.0.9 ) or send unicast packets, support plain text authentication and MD5 cipher text authentication, only accept legitimate domain routing updates
l support automatic routing, manual summary (summary automatic inaccurate, usually manually override automatic summary rollup, NO Auto-Summary or NO Summary )
RIP timers :
l update timer Update-30s , routing update cycle, every 30s send the complete routing table outwardly
l failure timer invalid-180s , in 180s within a route not received update information, the routing information is invalid
l suppression timer Holddown-180s , after receiving the second-best route timing 180s effect after
l refresh timer flush-240s , the 240s within a certain route is not received updated information, the routing information is deleted
RIP prevent routing loop technology:
L RIP maximum hop count using the hop count as a metric, defined 15, more than 15 hops is unreachable network
l horizontal split, one after the interfaces receive the route entry route entry can not be sent from the interface, to avoid loops
l routing poisoning, toxic reversed, after a certain network is not reachable, immediately set the cost to 16 hops, and sent out (split-horizon may be covered) from all interfaces
l after suppression timer received suboptimal route entry to be inhibited before the timer expires updates the routing table
l triggered update, the network topology change occurs (i.e. a change in the route entry), the router sends updated routing information immediately outwardly
RIP protocol Disadvantages:
l The maximum hop count of 15 , the network size is limited
l routing update transmission cycle 30s , slow convergence network, typically 2-4 minutes
l network hops little path is not necessarily the optimal path
RIP configuration commands
[H3C] rip // Enable RIP and enter the RIP configuration view
[H3C-rip-1] version 2 // version configured RIPv2
[H3C-rip-1] undo summary // Close routing information automatically aggregate
[H3C-rip-1] network 10.0.0.0 // advertised IP belonging 10.0.0.0 network ports enable the RIP protocol
[H3C-rip-1] network 172.16.0.0 // advertised IP belonging 172.16.0.0 network ports enable the RIP protocol
[R1-Serial1 / 0] no rip split-horizon // Close S1 / 0 ports split level
[R1-Serial1 / 0] rip authentication-mode md5 rfc2453 plain 123 // S1 / 0 port enable md5 authentication is by RFC2453 , secretarial next key 123
[R1-rip-1] silent -interface Serial 1/0 // passive interfaces, interfaces muting, only accept Send Routing Information
[R1-rip-1] peer 10.1.1.1 // specified neighbor to unicast 10.1.1.1 update Send Routing
Routing black hole
Example One:
172.16.2.0/24 and 172.16.3.0/24 former 23 is bits are consistent, may be summarized as 172.16.2.0/23 , conversely can only draw 172.16.2.0 / 24 and 172.16.3.0/24 two networks, an accurate address summary no problem
Example Two:
172.16.1.0/24 and 172.16.2.0/24 former 22 is bit uniform , can be summarized as 172.16.0.0/22 , contrary to give four network 172.16.0.0/24 , 172.16.1.0/24 , 172.16.2.0/24 and 172.16. 3.0 / 24 . 172.16.0.0/24 and 172.16.3.0/24 does not exist, but will continue to be sent to other devices both data network, i.e. routing black hole is formed.