something confusing on pg.395

[hassaan]

the output of "show ip protocols " looks something like this - starting at line 6 on page 395
------------------------
Default version control: send version 1, receive any version
Interface
Serial0/0
Serial0/1

Routing for Networks:
10.0.0.0

Routing Information Sources:
Gateway
10.168.11.14
------------------------

Now moving on to the output of "show ip int brief" command on the same page - only the first two columns of the output
------------------------
Interface IP-Address
FastEthernet0/0 192.168.18.1
Serial0/0 10.168.11.17
FastEthernet0/1 unassigned
Serial0/1 192.168.11.21
------------------------

The text after the output says, "we're using RIP routing for network 10.0.0.0"
and then it says, "only serial0/0 and serial0/1 are participating in the RIP network."

MY QUESTION IS:
How is interface serial0/1 participating in the RIP network when the network it's configured in (i.e. 192.168.11.0) is not being advertised by RIP?

[Vasilis]

Hello,

A router with RIP configured automatically sends its RIP updates out all interfaces, unless otherwise configured (passive-interface command). The s0/1 interface in this example is a part of the routing process, since it is connected and functional. The ip address of the interface is not in the 10.0.0.0 network, but remember that this is not OSPF. The interface will still advertise the configured 10.0.0.0 network no matter its ip address. The problem posted by this example is that the network in which this interface is configured in, will not be advertised by the router, what leads to incomplete routing tables.

[Fuzz]

If that's true, wouldn't the sh ip protocols also list Fa0/0 as a listed interface? Do we have enough information to make a conclusion on this?

[hassaan]

If that's true, wouldn't the sh ip protocols also list Fa0/0 as a listed interface? Do we have enough information to make a conclusion on this?

That's what I was wondering.

[hassaan]

I'd really appreciate some help from Mr. Lammle on this.

[Vasilis]

Hello,

your question is right afterall. Quote: "After you define the networks with the network command, RIP begins to advertise and listen for updates on those interfaces that are contained in that classful network. For instance, if you did not configure the network 192.168.1.0 statement in RouterA, you would never be able to send or receive updates on the serial interface..." Keep in mind that the routing protocol does not listen to or learn from advertisements on an interface, unless you include their respective networks in the routing protocol process with the network command." -end of quote
So normally, the S0/1 should not be included in the routing process since not included in the RIP process with the network command, exactly like the f0/0. I believe that's a mistake that has been made there, but I will too wait for Mr. Lammle to comment on this.

Greetings

[hassaan]

ya now we're on the same track :)
Mr. Lammle we need your assistance!

[pconlan]

Yes, the show ip protocols shows only the classful network of 10.0.0.0 will participate in RIP updates, so only interfaces configured in the 10.0.0.0 network will participate in RIP, in this example.
Thinking back, S0/1 was configured in the 10.0.0.0 network in chapter 4, but I changed it for another example and forgot to set it back to it's original IP address and I didn't notice that when writing about this new example.
Thanks!
Todd Lammle

[pconlan]

I am using Pat's computer right now (remember that Pat Conlan works for me as an instructor at GlobalNet Training), which is why my comments are showing up under his login at the moment.
Cheers!
Todd

[hassaan]

Thanks a lot sir!

[Vasilis]

Hello

I'm glad to see that this question is solved. But I would like to bring this to your attention too. In page 380 of the book it says: quote:"As shown in Figure 6.13, each router has only the directly connected networks in each routing table. Each router sends its complete routing table out to each active interface. In one of the test sets in the CD a question gives the same answer to a more general question about the behaviour of distance vector routing protocols.

If distance vector protocols actually send their routing tables only out those interfaces that are included in the advertised networks (configured with the network command) then what the book says is wrong and misleading (see my first answer to this thread which I based exactly on P.380 of the book)

[lildeezul]

routing protocols send updates out the interfaces specified in the network command, if thier active. and no passive interface is configured ( like with OSPF and EIGRP)