05-05-2010 07:57 AM - edited 03-04-2019 08:22 AM
Would the below output snippet of "show interfaces switching" be an acceptable amount of process switched packets? Or would that be considered high? Also it appears the CEF is dropping packets due to the Cache misses, is that correct?
Protocol IP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 198527 20305755 137600 11936300
Cache misses 58283 - - -
Fast 114698940 1539757122 176439333 2845662647
Auton/SSE 0 0 0 0
05-05-2010 08:08 AM
When using process switching, the operation is to populate the fast cache, if the network is not stable, network conditions can cause an increased number of Cache misses (an instance where no cache entry matches a packet ) and can result in a high number of packets be process switched!.
Francisco
05-05-2010 08:11 AM
OK, I am troubleshooting High CPU spikes and stumbled accross the
these cache misses. But...I am unclear on
your answer...so to clearify, are you saying the amount of process switched packets in the output I provided is a High amount?
05-05-2010 08:17 AM
Can you post "show cef drop" and "show interface switching" (sorry o think you already posted show interface switching)
05-05-2010 08:38 AM
See below....
router#show cef drop
CEF Drop Statistics
Slot Encap_fail Unresolved Unsupported No_route No_adj ChkSum_Err
RP 88087 195 0 62615 0 0
router#show interfaces switching
FastEthernet0/0
Throttle count 0
Drops RP 0 SP 0
SPD Flushes Fast 0 SSE 0
SPD Aggress Fast 0
SPD Priority Inputs 201275 Drops 0
Protocol IP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 200009 20442235 138702 12022536
Cache misses 58283 - - -
Fast 114971009 1593045035 176788338 3081229314
Auton/SSE 0 0 0 0
Protocol DEC MOP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 988 76076
Cache misses 0 - - -
Fast 0 0 0 0
Auton/SSE 0 0 0 0
Protocol ARP
Switching path Pkts In Chars In Pkts Out Chars Out
--More-- Process 201217 12073028 224361 13461660
Cache misses 0 - - -
Fast 0 0 0 0
Auton/SSE 0 0 0 0
Protocol CDP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 46150 5278389 19686 8726589
Cache misses 0 - - -
Fast 0 0 0 0
Auton/SSE 0 0 0 0
Protocol PPPoE
Switching path Pkts In Chars In Pkts Out Chars Out
Process 5505 412052 224658 13533231
Cache misses 0 - - -
Fast 2830219 540707918 3517128 2544941938
Auton/SSE 0 0 0 0
Protocol Other
Switching path Pkts In Chars In Pkts Out Chars Out
Process 147 10770 59641 3578460
Cache misses 0 - - -
--More-- Fast 0 0 0 0
Auton/SSE 0 0 0 0
NOTE: all counts are cumulative and reset only after a reload.
FastEthernet0/1
Throttle count 0
Drops RP 164 SP 0
SPD Flushes Fast 0 SSE 0
SPD Aggress Fast 0
SPD Priority Inputs 13604 Drops 0
Protocol IP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 642732 58538192 653639 63688078
Cache misses 9 - - -
Fast 181742646 1495447728 118768428 1806409122
Auton/SSE 0 0 0 0
Protocol DEC MOP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 988 76076
Cache misses 0 - - -
Fast 0 0 0 0
--More Auton/SSE 0 0 0 0
Protocol ARP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 87 5220 243 14580
Cache misses 0 - - -
Fast 0 0 0 0
Auton/SSE 0 0 0 0
Protocol CDP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 9814 4035204
Cache misses 0 - - -
Fast 0 0 0 0
Auton/SSE 0 0 0 0
Protocol Other
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 59065 3543900
Cache misses 0 - - -
Fast 0 0 0 0
Auton/SSE 0 0 0 0
--More-- NOTE: all counts are cumulative and reset only after a reload.
Interface Serial0/1/0 is disabled
Interface Serial0/2/0 is disabled
Virtual-Access1
All statistics for this interface are zero.
Virtual-Template1
All statistics for this interface are zero.
Virtual-Access2
All statistics for this interface are zero.
Virtual-Access3
Throttle count 0
Drops RP 0 SP 0
SPD Flushes Fast 0 SSE 0
SPD Aggress Fast 0
SPD Priority Inputs 333 Drops 0
Protocol IP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 1551 119275 1542 118692
Cache misses 1940 - - -
Fast 221290 35391142 405650 263132083
Auton/SSE 0 0 0 0
Protocol PPPoE
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 1 18
Cache misses 0 - - -
Fast 0 0 2572 25720
Auton/SSE 0 0 0 0
Protocol Other
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 48841 683677
Cache misses 0 - - -
Fast 134612 1608414 0 0
Auton/SSE 0 0 0 0
NOTE: all counts are cumulative and reset only after a reload.
Virtual-Access4
--More-- Throttle count 0
Drops RP 0 SP 0
SPD Flushes Fast 0 SSE 0
SPD Aggress Fast 0
SPD Priority Inputs 184 Drops 0
Protocol IP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 6 508 94 2352
Cache misses 0 - - -
Fast 407691 111053673 619356 426091885
Auton/SSE 0 0 0 0
Protocol PPPoE
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 0 0
Cache misses 0 - - -
Fast 0 0 2090 20900
Auton/SSE 0 0 0 0
Protocol Other
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 32930 460716
--More-- Cache misses 0 - - -
Fast 92261 1061814 0 0
Auton/SSE 0 0 0 0
NOTE: all counts are cumulative and reset only after a reload.
Virtual-Access5
Throttle count 0
Drops RP 0 SP 0
SPD Flushes Fast 0 SSE 0
SPD Aggress Fast 0
SPD Priority Inputs 186 Drops 0
Protocol IP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 34 2576 103 3240
Cache misses 8 - - -
Fast 182462 35921082 271895 186012176
Auton/SSE 0 0 0 0
Protocol PPPoE
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 1 24
Cache misses 0 - - -
--More-- Fast 0 0 1357 13570
Auton/SSE 0 0 0 0
Protocol Other
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 19502 272784
Cache misses 0 - - -
Fast 49611 642742 0 0
Auton/SSE 0 0 0 0
NOTE: all counts are cumulative and reset only after a reload.
Virtual-Access6
Throttle count 0
Drops RP 0 SP 0
SPD Flushes Fast 0 SSE 0
SPD Aggress Fast 0
SPD Priority Inputs 570 Drops 0
Protocol IP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 732 51861 808 56976
Cache misses 1354 - - -
Fast 256387 90681993 354825 234555456
--More-- Auton/SSE 0 0 0 0
Protocol PPPoE
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 0 0
Cache misses 0 - - -
Fast 0 0 1372 13720
Auton/SSE 0 0 0 0
Protocol Other
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 23288 325609
Cache misses 0 - - -
Fast 60972 760716 0 0
Auton/SSE 0 0 0 0
NOTE: all counts are cumulative and reset only after a reload.
Virtual-Access7
Throttle count 0
Drops RP 0 SP 0
SPD Flushes Fast 0 SSE 0
SPD Aggress Fast 0
SPD Priority Inputs 440 Drops 0
--More--
Protocol IP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 771 70982 785 55626
Cache misses 1427 - - -
Fast 344677 87538302 466489 323174015
Auton/SSE 0 0 0 0
Protocol PPPoE
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 0 0
Cache misses 0 - - -
Fast 0 0 1015 10150
Auton/SSE 0 0 0 0
Protocol Other
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 19887 278034
Cache misses 0 - - -
Fast 47650 665630 0 0
Auton/SSE 0 0 0 0
NOTE: all counts are cumulative and reset only after a reload.
--More-- Virtual-Access8
Throttle count 0
Drops RP 0 SP 0
SPD Flushes Fast 0 SSE 0
SPD Aggress Fast 0
SPD Priority Inputs 4 Drops 0
Protocol IP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 2 48
Cache misses 0 - - -
Fast 549878 77643459 937254 676136368
Auton/SSE 0 0 0 0
Protocol PPPoE
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 0 0
Cache misses 0 - - -
Fast 0 0 1976 19760
Auton/SSE 0 0 0 0
Protocol Other
Switching path Pkts In Chars In Pkts Out Chars Out
--More-- Process 0 0 55435 776085
Cache misses 0 - - -
Fast 158559 1807258 0 0
Auton/SSE 0 0 0 0
NOTE: all counts are cumulative and reset only after a reload.
Virtual-Access9
Throttle count 0
Drops RP 0 SP 0
SPD Flushes Fast 0 SSE 0
SPD Aggress Fast 0
SPD Priority Inputs 253 Drops 0
Protocol IP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 85 6837 158 5904
Cache misses 64 - - -
Fast 275892 38647213 451171 354169113
Auton/SSE 0 0 0 0
Protocol PPPoE
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 0 0
--More-- Cache misses 0 - - -
Fast 0 0 108 1080
Auton/SSE 0 0 0 0
Protocol Other
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 20296 283775
Cache misses 0 - - -
Fast 48282 680188 0 0
Auton/SSE 0 0 0 0
NOTE: all counts are cumulative and reset only after a reload.
Loopback1
All statistics for this interface are zero.
Tunnel2
Protocol IP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 619 64716 518 43512
Cache misses 0 - - -
Fast 603324 65158992 438346 47341368
Auton/SSE 0 0 0 0
--More--
NOTE: all counts are cumulative and reset only after a reload.
router#
05-05-2010 08:58 AM
Are you having network issues on this router, routing changes or high CPU?
I am seeing number of packets dropped could be related to packet exceeding the limit for packet ounted to the RP!! Also seeing packets being dropped by CEF!!!
router#show cef drop
CEF Drop Statistics
Slot Encap_fail Unresolved Unsupported No_route No_adj ChkSum_Err
RP 88087 195 0 62615 0 0
Protocol ARP
Switching path Pkts In Chars In Pkts Out Chars Out
-- Process 201217 12073028 224361 13461660
Protocol IP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 200009 20442235 138702 12022536
Cache misses 58283
http://www.cisco.com/en/US/products/hw/routers/ps359/products_tech_note09186a00801c2af0.shtml
05-05-2010 09:36 AM
Yes, there are occasional HIGH CPU spikes. What do you mean "related to packet exceeding the limit for packet ounted to the RP!!"?
05-05-2010 09:49 AM
sorry i meant punted not ounted.
Based on your CEF output under "Encap_fail", i am seeing cef drops. I got this direct from Cisco doc saying that The "Encap_fail" field indicates the number of packets dropped after exceeding the limit for packets punted to the processor because of missing adjecency information such as an unresolved ARP request. Note that CEF throttles packets punted to the process level at a rate of one packet per second to aid in suspectibility of Dos attacks.
05-05-2010 09:50 AM
see this link for troubleshoot CEF related issues
http://www.cisco.com/en/US/products/hw/routers/ps359/products_tech_note09186a00801c2af0.shtml
05-10-2010 11:38 AM
From this cisco document, there are numerous causes for this issue.
Do any of you know if there is a typical cause? How would you recomend proceding? One thing I noticed is I see around 100,000 broadcast packets recieved on the interface which I was suspious of and have condsidered issuing Mac-address accounting in that interface to try and see if all those broadcast were coming from one source address.
The main thing that has got me concerned is the amount of CEF drops or amount of "Encap_fail". Any guidance in this issue would be greatly appreciated.
05-11-2010 10:04 AM
I would start by debuging cef drops "debug ip cef drops" to see what traffic is being cef-dropped so you can track what apps is affected.
Francisco.
05-05-2010 09:46 AM
These rates are definitely acceptable.
In most cases, process switched packets are sourced or destined for the router.
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