[c-nsp] ICMP Mask Requests on 6500

[John Neiberger]

On Fri, Jan 7, 2011 at 3:10 PM, John Neiberger <jneiberger at gmail.com> wrote:
> This is an interesting one. I have a TAC case open, but I thought I'd
> check to see if anyone had ever seen this before. We had some old
> equipment that uses ICMP mask requests to get its subnet information.
> When this equipment is connected to an old 7513 running 11.1 code, the
> router replies to the mask request with an ICMP mask reply. When we
> move that device to a 6513 (Sup720, 12.2 code) we can see the mask
> request come in, but the 6500 never sends a reply. According to Cisco,
> the code to do the reply is in the IOS, 12.2(18)SXF9, so it must be a
> bug. However, it also didn't work in 12.2(33)SXI5.
>
> I'm beginning to think the code is actually being deprecated since no
> one really uses this feature any more. Have any of you ever had to
> deal with ICMP mask requests and replies before?
>
> Thanks!
> John
>

I forgot a key piece of information. "ip mask-reply" is configured and
"show ip int" indicates that mask replies are always sent, yet they
are not actually being sent.

Thanks