[c-nsp] ARP and less specific interface entries

[Peter Hicks]

Frank Bulk - iNAME wrote:

> We have some devices with management IPs in the 10.1.0.0/16 range that I 
> manage and I needed to split up into two groups.  All the devices were 
> statically assigned an IP address in the form of 10.1.3.x/255.255.0.0, so I 
> added two more secondaries for router interface fa0.5: 10.1.3.1/24 and 
> 10.1.4.1/24, the two desired groups.  We then re-IPed the devices from 
> 10.1.3.x/16 to 10.1.3.x/24 and 10.1.4.x/24.
> 
> NAGIOS went ballistic, claiming that devices from both 10.1.3.x and 10.1.4.x
>  were down.  If we attached a PC in that network with a 10.1.3.x/16 address 
> it could ping them just fine.  If we rebooted the device we were sometimes 
> able to ping it for a while, but not always.  That led me to believe it was 
> an ARP issue on the router.  The 1721 running 12.4(6)T 
> (c1700-ipbase-mz.124-6.T.bin) had all kinds of incomplete ARP entries for 
> those unpingable IPs.

There are only two types of ARP entry - complete and incomplete.

Can you post your interface configuration, please?  It's not clear whether
you're using secondary addresses or sub-interfaces.

It appears that you're trying to work with overlapping subnets on interfaces 
the same router, which won't work (unless you're using different VRFs).


Peter

-- 
Peter Hicks | e: my.name at poggs.co.uk | g: 0xE7C839F4 | w: www.poggs.com

   A: Because it destroys the flow of the conversation
   Q: Why is top-posting bad?