[c-nsp] Sup32 TCAM limit

[Julio Arruda]

 From what I understand, the 'less specific prefix' punted routes would 
not be a problem, the problem was if less specific where in the TCAMs 
while more specifics not ? This would make for some interesting routing :-)


marco at linuxgoeroe.dhs.org wrote:
>>> What I do not understand is what would happen to the routes being
>>> inserted
>>> above this limit. Would such routes be 'soft' routed ? Is there also a
>>> treshold for
>> Prefixes that cannot fit in the TCAM are punted to the MSFC, and thus
>> software switched, probably in an interrupt based CEF path.
> 
> That's what supposed to happen, yes. But I ran into this recently (with a
> SUP720 now upgraded to XL) and the box didn't punt the packets. It just
> hardware switched them based on what was in the TCAM.
> 
> Result was that the correct route was in the routing table and CEF FIB,
> but packets got dropped or shunted elsewhere without any sign except the
> TCAM_FULL messages, and those didn't look right either (no route in the
> message at all or junk chars where it should be).
> 
> This was the sup running hybrid, IOS 12.2(17d)SXB8 on the MSFC and CatOS
> 8.6(1) on the SP.
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