sho ip route "longer" parameter question

From: Hank Nussbacher (hank@att.net.il)
Date: Sun Feb 24 2002 - 07:42:25 EST


According to the Cisco documentation:

[http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/np1_r/1rprt1/1rindep.htm]

The following is sample output using the longer-prefixes keyword. When the
longer-prefixes keyword is included, the address and mask pair becomes the
prefix, and any address that matches that prefix is displayed. Therefore,
multiple addresses are displayed.

In the following example, the logical AND operation is performed on the
source address 128.0.0.0 and the mask 128.0.0.0, resulting in 128.0.0.0.
Each destination in the routing table is also logically ANDed with the mask
and compared to that result of 128.0.0.0. Any destinations that fall into
that range are displayed in the output...

Here are samples we have run:

show ip route 192.168.168.16 255.255.255.248 longer
      192.168.168.0/24 is variably subnetted, 4 subnets, 4 masks
S 192.168.168.16/30 [1/0] via 104.90.64.134
S 192.168.168.16/28 [1/0] via 104.90.64.130

c751e1#show ip route 192.168.168.16 255.255.255.252 longer
      192.168.168.0/24 is variably subnetted, 4 subnets, 4 masks
S 192.168.168.16/30 [1/0] via 104.90.64.134
S 192.168.168.16/28 [1/0] via 104.90.64.130

c751e1#show ip route 192.168.252.0 255.255.255.128 longer
S 192.168.252.0/24 [4/0] via 192.168.8.2

dexamol>sho ip rou 192.168.72.0 255.255.255.0 longer
B 192.168.72.224/27 [15/0] via 192.168.75.42, 6d00h
B 192.168.72.208/28 [15/0] via 192.168.72.194, 6d00h
B 192.168.72.192/28 [15/0] via 192.168.177.2, 6d00h
B 192.168.72.160/27 [15/0] via 192.168.177.2, 6d00h
B 192.168.72.128/27 [15/0] via 192.168.177.2, 6d00h
O E2 192.168.72.32/27 [110/20] via 10.2.2.8, 3d00h, FastEthernet0/0
B 192.168.72.0/27 [15/0] via 192.168.75.42, 6d00h
S 192.168.72.0/21 is directly connected, Null0

I just can't understand if there is some Cisco bug we are hitting (commands
were run on multiple versions) or whether we are not understanding properly
the "longer" attribute. Any help appreciated.

Thanks,
Hank



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