[c-nsp] ARP and less specific interface entries

[Frank Bulk - iNAME]

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.  

After poking around in Google at some ARP stuff, I decided to remove the
10.1.0.1/16 entry from fa0.5, and voila, everything started working again.

Does IOS have some kind of issue with properly creating ARP entries for
clients if there is a less-specific and more-specific entry on an interface?

Regards,

Frank