[c-nsp] Problems with secondary ip address on subinterfaces

[Shakeel Ahmad]

>>> however when these address are configured as secondarys it doesnt want
to work.

Have you tried extended ping ?? with same subnet source ?



On 12/17/06, Paul Cairney <lists at cairney.me.uk> wrote:
>
> Hi,
>
> I am having some odd issues with secondary IP addresses configured on a
> couple of 2821's running c2800nm-spservicesk9-mz.124-7b.bin.
>
> Basically I have an MPLS link between two sites and will have a pair of
> 2800's at each end. Until the second site is up and running I have got the
> provider to add some SVI's on their kit at each end with RFC1918 ip's to
> allow me to verify connectivity. Both 2821's have Gi0/0 into a 3560G and the
> provider circuit also termiates on this (the 3560 is not doing any layer3
> for the time being).
>
> When these ip's are configured as the primary ip's on this subinterface
> (either standalone or with my own ip's as secondarys) then I can ping the
> providers ip's no problem (10.0.25.2 and 10.0.25.3) however when these
> address are configured as secondarys it doesnt want to work.
>
> I currently have router1 with the desired configuration of my own ip's as
> the primary and the provider issued rfc1918 ip's as secondary, the plan
> being to remove these when I have my own kit at the other end of the link.
> To try and establish the cause of the issue I configured things the other
> way arround on route2 (see below for configs) and this appears to work fine;
> I can ping both the providers remote ip's and I can also ping between my own
> IP's (blah1 and blah2).
>
> The really weird thing is that my own IP's work fine regardless of which
> way round they are configured as does pings between these two routers using
> the 10.0.25.4/10.0.25.05 address (which will not touch the providers
> network). I have also tried reversing the configuration on both routers so
> the 10.0.25.0/24 ip's are primary and secondary on both routers to no
> avail... it just doesnt want to work at all on a router when configured as a
> secondary.
>
>
> Hopefully there is a known issue and I am not trying to do anything silly,
> I know secondarys can cause issues with OSPF but I have never had any real
> issues with seconary ip's at this low a level.
>
>
> I have tried to include as much relevant info as I can think of; if anyone
> can suggest further information that may assist in diagnosis then please let
> me know.
>
>
> Thanks,
>
> Paul
>
>
>
>
>
> CONFIGS SNIPPETS:
>
> router1:
>
> interface GigabitEthernet0/0.1025
> encapsulation dot1Q 1025
> ip address 10.0.25.4 255.255.255.0 secondary
> ip address <blah1> 255.255.255.240
> end
>
> router2:
>
> interface GigabitEthernet0/0.1025
> encapsulation dot1Q 1025
> ip address <blah2> 255.255.255.240 secondary
> ip address 10.0.25.5 255.255.255.0
> end
>
> ROUTES:
>
> router1#sh ip route 10.0.25.2
> Routing entry for 10.0.25.0/24
> Known via "connected", distance 0, metric 0 (connected, via interface)
> Redistributing via ospf 65071
> Routing Descriptor Blocks:
> * directly connected, via GigabitEthernet0/0.1025
>      Route metric is 0, traffic share count is 1
>
> router2#sh ip route 10.0.25.2
> Routing entry for 10.0.25.0/24
> Known via "connected", distance 0, metric 0 (connected, via interface)
> Redistributing via ospf 65071
> Routing Descriptor Blocks:
> * directly connected, via GigabitEthernet0/0.1025
>      Route metric is 0, traffic share count is 1
>
> CEF:
>
> router1#sh ip cef gi0/0.1025
> Prefix              Next Hop             Interface
> 10.0.25.0/24        attached             GigabitEthernet0/0.1025
> 10.0.25.2/32        10.0.25.2            GigabitEthernet0/0.1025
> 10.0.25.3/32        10.0.25.3            GigabitEthernet0/0.1025
> 10.0.25.5/32        10.0.25.5            GigabitEthernet0/0.1025
>
> router2#sh ip cef gi0/0.1025
> Prefix              Next Hop             Interface
> 10.0.25.0/24        attached             GigabitEthernet0/0.1025
> 10.0.25.2/32        10.0.25.2            GigabitEthernet0/0.1025
> 10.0.25.3/32        10.0.25.3            GigabitEthernet0/0.1025
> 10.0.25.4/32        10.0.25.4            GigabitEthernet0/0.1025
>
> PINGS:
>
> router1#ping <blah2>
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to <blah2>, timeout is 2 seconds:
> !!!!!
> Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
>
> router1#ping 10.0.25.2
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 10.0.25.2, timeout is 2 seconds:
> .....
> Success rate is 0 percent (0/5)
>
> router1#ping 10.0.25.3
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 10.0.25.3, timeout is 2 seconds:
> .....
> Success rate is 0 percent (0/5)
>
> router1#ping 10.0.25.5
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 10.0.25.5, timeout is 2 seconds:
> !!!!!
> Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms
>
>
> router2#ping <blah1>
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to <blah1>, timeout is 2 seconds:
> !!!!!
> Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
>
> router2#ping 10.0.25.2
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 10.0.25.2, timeout is 2 seconds:
> !!!!!
> Success rate is 100 percent (5/5), round-trip min/avg/max = 76/76/76 ms
>
> router2#ping 10.0.25.3
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 10.0.25.3, timeout is 2 seconds:
> !!!!!
> Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
>
> router2#ping 10.0.25.4
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 10.0.25.4, timeout is 2 seconds:
> !!!!!
> Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms
>
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