[c-nsp] 7301 NPE-G1 gigabit overruns

[john douglas]

Hi All,

I am hoping someone may have some guidance.

We have some 7301 NPE-G1 running 12.2(33)SRC3 connected to Catalyst
3560 switch, dot1q trunking with a few Vlans. I find on the 7301
router whenever I try to drive a given gigabit sub interface beyond
about 200mbps I begin to see Input Errors (Overruns) incrementing on
the physical interface and begin exhibiting packet loss. Under the
show controller information I see rx_overrun and rx_int_drop
incrementing - all other Rx error values under "Statistics" section
are zero. On the switch I see pause input incrementing, but no errors.
Cpu is 40%.

I have read other postings about this being attributed to microburst
of traffic but I am still a little unclear I am trying to work out

1) Does the G1 correctly support pause frames?

2) Are there any knobs we can tweak - or we simply hitting the limits
of the silicon?

The short term solution has been to spread the vlan sub interfaces
over the 3 gig interfaces however this leaves me in a situation where
I cannot really use EEM to migrate sub interface config from one
gigabit interface to another should there be a failure, as the target
interface will being exhibiting overruns and loss.

Any advice appreciated,

Kind regards,

John