"Variably subnetted" & EIGRP/OSPF Questions

Bill Kaster

I've set up a couple basic serial WAN links between three 2524 routers with chap authentication. I get the following output:

R2#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route

Gateway of last resort is not set

192.168.2.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.2.0/30 is directly connected, Serial0
C 192.168.2.1/32 is directly connected, Serial0
192.168.3.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.3.2/32 is directly connected, Serial1
C 192.168.3.0/30 is directly connected, Serial1

The WAN links themselves are fine; LCP is being sent when it should and everything is fine on that end in general. I set up a /30 mask for both WAN links, as it wastes the fewest amount of address space, yet I see a /32 there, and that's what is puzzling. Maybe I need to refresh myself on subnetting, but I believe /32 doesn't exist, so what's the deal?[/b]

dtlokee

the /32 is a host route, it is there to define the neighbor at the other end of the link, installed by NCP during the PPP negotiation. If you use the "no peer neighbor-route" command on the serial interface it will remove it.

Bill Kaster

I just tried no peer neighbor-route in interface configuration mode, but still get the same "variably subnetted" output with a show ip route command.

Not that it's a big deal. I just wanted to make sure I had set everything up correctly.

dtlokee

You need to shut no shut the interface, this will cause NCP to remove the route.

Bill Kaster

Thanks, that worked great.

One last question; if I try to implement EIGRP or OSPF or some other routing protocol in this 3 router network, do I have to disable ppp or something? Because I tried applying eigrp just now and my ip route command shows this:

R2#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route

Gateway of last resort is not set

192.168.2.0/30 is subnetted, 1 subnets
C 192.168.2.0 is directly connected, Serial0
192.168.3.0/30 is subnetted, 1 subnets
C 192.168.3.0 is directly connected, Serial1

Obviously, I want those two "C" to be D's for EIGRP to actually be running.

dtlokee

do you have any routes being advertised by the other routers that are not directly connected? Remember connected routes have an AD of 0 and EIGRP has an AD of 90, so the connected route will override the EIGRP route. You can check the "sh ip eigrp topology" command to see if you're learnign any EIGRP routes.

Bill Kaster

All I get when I do an show topology is this:

R0#show ip eigrp topology
IP-EIGRP Topology Table for AS(100)/ID(192.168.6.254)
R0#

The output that the 5th edition Sybex book shows for show ip eigrp topology is quite different. Is there another command that expands the topology command results?

dtlokee

I think there is a glitch in your configuration of EIGRP somewhere, check to see if you have eighbors (sh ip eigrp neighbors) if you don't check your network statements, if you do then make sure the neighbors have networks to advertise and the interfaces are all in an up/up state (for example if you're trying t advertise an Ethernet network without it being up/up then the router won't advertise the link, there is a workaround to this you can put the command "no keepalives" on the ethernet interface and it will always be up/up even if you don't connect it to anything)

mwgood

Bill Kaster wrote:

192.168.2.0/30 is subnetted, 1 subnets
C 192.168.2.0 is directly connected, Serial0
192.168.3.0/30 is subnetted, 1 subnets
C 192.168.3.0 is directly connected, Serial1

Obviously, I want those two "C" to be D's for EIGRP to actually be running.

Your "C" should stay "C" - even with EIGRP working. You need to ensure that you have EIGRP enabled on your other routers, and that you also have networks other than connected networks being advertised. There is no reason for a router to install a network from EIGRP when it already knows about it as connected. The administrative distances are setup to prevent that from happening.