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New Member

Routing table strangeness

I was checking the routing table on my 3750 stack and noticed something that appears abnormal to me.  My route statements are:

ip route 24.52.116.0 255.255.255.0 10.0.6.254

ip route 24.52.117.224 255.255.255.248 10.0.6.254

ip route 72.240.116.0 255.255.255.0 10.0.6.254

ip route 156.154.33.0 255.255.255.0 10.0.5.2

ip route 172.30.10.0 255.255.254.0 10.255.255.251

When I look in the routing table, the first two appear to be fine:

     24.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

S       24.52.116.0/24 [1/0] via 10.0.6.254

S       24.52.117.224/29 [1/0] via 10.0.6.254

When I look at the other three, they do not - they appear to be subnetting incorrectly:

     72.0.0.0/24 is subnetted, 1 subnets

S       72.240.116.0 [1/0] via 10.0.6.254  <-- this should be a /24

    172.30.0.0/23 is subnetted, 1 subnets

S       172.30.10.0 [1/0] via 10.255.255.251

     156.154.0.0/24 is subnetted, 1 subnets

S       156.154.33.0 [1/0] via 10.0.5.2

'ip classless' is on for the switch.  Any ideas?  Is it still routing correctly despite what these entries say?

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Silver

Routing table strangeness

The original poster is confused and seems to want the routing table to correctly identify each network with its classful identity as class A or class B or class C. But what the routing table does when there is only a single subnet in the network is to identify the network using the mask specified by the configured route.

So if the static route says 172.30.10.0 255.255.254.0

then the routing table says 172.30.0.0/23 which corresponds exactly to the configured mask.

HTH

Rick

5 REPLIES
New Member

Routing table strangeness

whats wrong? i dont understand...  is a /24 and reachable with a static route. The first 2 was from the same net 24.0.0.0 and after specify that one is a /24 and other /29... tryng to add a 72.240.117.0/23 and you will see a /8 and after a /24 and a /23.

Is this what you mean?

Purple

Routing table strangeness

Hi,

everything is normal and to test it just do traceroutes.

Regards.

Alain

Don't forget to rate helpful posts.
Hall of Fame Super Silver

Routing table strangeness

The original poster is confused and seems to want the routing table to correctly identify each network with its classful identity as class A or class B or class C. But what the routing table does when there is only a single subnet in the network is to identify the network using the mask specified by the configured route.

So if the static route says 172.30.10.0 255.255.254.0

then the routing table says 172.30.0.0/23 which corresponds exactly to the configured mask.

HTH

Rick

New Member

Routing table strangeness

Thanks Rick - that was what was throwing me off.

Hall of Fame Super Silver

Routing table strangeness

I am glad that my explanation did help to clarify the issue for you. Thank you for using the rating system to mark this question as answered (and thanks for the points). It makes the forum more useful when people can read a question and can know that a correct answer was provided. Your marking has contributed to this process..

HTH

Rick

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