[c-nsp] Cisco 7206VXR with NPE-G1

[Matthew Huff]

Even with “ip options drop”, we are still seeing a fraction of packets being cpu switched (about 0.2% input and 1% output)  even though we are using CEF. Looks like they are mostly door-knob packets destined for the router itself (which is ACL’d) or some other annoyance. We tuned the buffers to solve the cosmetic counter issue with input/output errors. Since we increased the buffers, the counters have been clean, and the “show buffers” did show a shortage of buffers, so even on the 7200 with particles, perhaps the CLI uses the buffers construct regardless. Maybe it was just a placebo effect.

rtr-inet2#sh int gi0/1 stats
GigabitEthernet0/1
          Switching path    Pkts In   Chars In   Pkts Out  Chars Out
               Processor    2824573  677403057    2958521  196941357
             Route cache  944226953  181329390  274701286 1591461341
                   Total  947051526  858732447  277659807 1788402698

rtr-inet2#sh ip cef switching statistics

Path   Reason                          Drop       Punt  Punt2Host
RP LES Packet destined for us             0    4377823          0
RP LES Total                              0    4377823          0

RP PAS No route                        3923          0          0
RP PAS Packet destined for us             0    4933417          8
RP PAS No adjacency                    3476          0          0
RP PAS Incomplete adjacency         1204250          0          0
RP PAS TTL expired                        0          0    2709278
RP PAS Routed to Null0            392389023          0          0
RP PAS Features                   151528682          0      22614
RP PAS IP redirects                       0          0      12358
RP PAS Neighbor resolution req       399660          0          0
RP PAS Total                      545529014    4933417    2744258

All    Total                      545529014    9311240    2744258

On Jul 8, 2015, at 4:13 AM, Lukas Tribus <luky-37 at hotmail.com<mailto:luky-37 at hotmail.com>> wrote:

"on a 10000". The 7200 uses particles, not buffers...

Also, its not relevant for CEF-switched traffic. So unless your configuration
requires fast-switching or process-switching, you don't need to worry about
buffer/particle tuning at all.


Lukas