Introduction to Distance vector algorithm

Reprinted from Http://blog.sina.com.cn/s/blog_635e1a9e0100z41v.html

The distance vector routing (vector-distance) algorithm sends the complete routing table to neighboring routers, and the neighboring routers combine the received routing table entries with their original routing tables to perfect the routing table.

Rumored route: Using the distance vector routing algorithm, because the router received updates only from the neighboring routers to the remote network confirmation information, it did not go to the field to find, so this way is dubbed as rumored route.

Pinhole congestion: (as shown below) when the RIP protocol is used to reach the network 172.16.10.0 has the same ad value of 120 and the same measure 1 jump, so the router automatically performs cyclic load balancing. Because the network 172.16.30.0 is a T1 link bandwidth is 1.544mb/s, and the network 172.16.20.0 is a 56K link but this is not known for RIP, this situation is called pinhole congestion.

Distance vector algorithm:

Update message contains fields: Destination network n, next hop router x, distance d.

An answer message sent by an adjacent router with an address of X, "Next hop" is changed to X, "distance" value plus 1;

There is no destination network N━┳━--Join the routing table

┗━━ have ━━ next jump is not X━┳━━ is---Update routing table

┗━ is not ━━d and the size of the original distance ━┳━━ small--Update routing table

┗━ is not small---do nothing