Chapter 5


1

RIP uses UDP port 520.

2

RIP uses a hop count metric. An unreachable network is indicated by setting the hop count to 16, which RIP interprets as an infinite distance.

3

RIP sends periodic updates every 30 seconds minus a small random variable that prevents the updates of neighboring routers from becoming synchronized.

4

A route entry is marked as unreachable if six updates are missed.

5

The garbage collection timer, or flush timer, is set when a route is declared unreachable. When the timer expires, the route is flushed from the route table. This process allows an unreachable route to remain in the routing table long enough for neighbors to be notified of its status.

6

The random timer, whose range is one to five seconds, prevents a "storm" of triggered updates during a topology change.

7

A Request message asks a router for an update. A Response message is an update.

8

A Request message might either ask for a full update, or in some special cases, it might ask for specific routes.

9

A Response is sent when the update timer expires, or upon reception of a Request message.

10

RIP updates do not include the subnet mask of the destination address, so a RIP router depends on the subnet masks of its own interfaces to determine how an attached major network address is subnetted. If a router does not have an attachment to a particular major network address, it has no way to know how that major network is subnetted. Therefore, no subnets of a major network address can be advertised into another major network.




CCIE Professional Development Routing TCP/IP (Vol. 12005)
Routing TCP/IP, Volume 1 (2nd Edition)
ISBN: 1587052024
EAN: 2147483647
Year: 2005
Pages: 233

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