标签为 ‘QOS’的文章

ASR9k Netflow and QOS order in the inbound direction

My customer match a issue that business traffics take IP6,7 flag, then the traffics auto mapping to EXP6,7 that cause control police congestion, and ISIS flapping due to BFD flap. So they want to check which traffics have incorrect flag by netflow, so need to check ording for netflow and QOS at input direction. I check some documents, nobody notice that, so the article will show test info, you can check if you need. Finaly test result: At ingress direction, packets will be cached first by netflow, then do other action in QOS.

Btw, due to auto mapping from TOS to EXP by range, e.g: TOS 192-223 will map to EXP6; TOS 223-255 will map to EXP7. So if we want to check the issue by netflow, suggest filter EXP data, as in my follow test, check by follow command:

RP/0/RSP1/CPU0:ASR9006-G#sh flow monitor test-mpls cache brief location 0/0/cpu0 | i 7-0
Fri Jan  8 04:57:39.604 UTC
      LDP        30000-7-0        40034-7-1           -                -                -                -          Te0/0/0/2       Te0/0/0/1       Fwd                  3888         36           Egr      0xff     icmp     0          2048


Mix for Fair-Queue and WRED on ASR1k’s class-default


当我们看到下面信息,能得出什么?OK, 咱们先不管是不是有burst,咱们先看看这些信息都代表什么。从qfp static drop中可以看到大部分都是TailDrop,那么这个TailDrop是谁执行的?那WRED又是在什么时候丢的包?数据包到底在default 队列遇到了什么导致了丢包?
Packets come in —> Per-flow queue —> WRED ?





TS for 6748 output drop

When you found have output queue drop for CEF720 LC, you can check follow step:
1. which port have issue, whether at same ASIC.
2. check whether have other error or have qos on issue port.
3. whether hw queue is full.

Follow is TS example:

Problem description:

Output queue have drop
1. After checked by follow command:
– show tech
– show inter switching x/x
– show int x/x counter de
– show inter x/x summary

3560 output drop affect voice vibrate

Refer to 3560 output drop increase issue.
All voice in one vlan 36.
And have some data vlan.

Follow are topology(summary):

 +-----------+            +-----------+
 |   6509    |            |   6509    |
 +-----\-----+            +-----/-----+
        \                     //
         \                   /