[c-nsp] Cisco ME-3400 and queue drops after IOS upgrade

[Ivan Gasparik]

FE ports of ME3400 with default configuration have output queue 
limited to 48 packets. It's not enough for burstable traffic, 
especially when the uplink of your ME3400 runs at 1Gb/s.
If you don't need any QoS, just attach a service-policy like:

policy-map max-queue
  class class-default
    queue-limit 544

to FE port (outbound direction).
QoS on ME3400 works, you can use hierarchical policy-map with 
traffic-shape at parent level and strict priority for VoIP data at 
child level. My experiences with this plattform showed a lot of 
limitations of QoS features, but in simple setup, when you don't need 
huge queues or many different classes it works well.

Ivan



On Tuesday 12 February 2008, Robert Hass wrote:
> Hi
>
> After IOS upgrade Cisco ME-3400 switch from IOS version 12.2(25)SEG
> to version 12.2(44)SE we occuring Output drops on FE ports. Before
> IOS upgrade we didn't saw any Output drops on these ports. Maybe
> previous version of IOS just didn't show drops in theris output ?
>
> FastEthernet0/5 is up, line protocol is up (connected)
>   ...
>   Full-duplex, 100Mb/s, media type is 10/100BaseTX
>   ...
>   Last clearing of "show interface" counters 1d00h
>   Input queue: 0/75/0/0 (size/max/drops/flushes); Total output
> drops: 5505 Queueing strategy: fifo
>   Output queue: 0/40 (size/max)
>   30 second input rate 4992000 bits/sec, 1405 packets/sec
>   30 second output rate 8840000 bits/sec, 9603 packets/sec
>      53058626 packets input, 20174009810 bytes, 0 no buffer
>      Received 259044 broadcasts (1054 multicasts)
>      0 runts, 0 giants, 0 throttles
>      0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
>      0 watchdog, 1054 multicast, 0 pause input
>      0 input packets with dribble condition detected
>      423839255 packets output, 57209899496 bytes, 0 underruns
>      0 output errors, 0 collisions, 0 interface resets
>      0 babbles, 0 late collision, 0 deferred
>      0 lost carrier, 0 no carrier, 0 PAUSE output
>      0 output buffer failures, 0 output buffers swapped out
>
> It's first my Catalyst switch smaller than 6500 which showing us
> Output drops in 'show interface' output, curios.
>
> BTW. Did anyone already configured some QoS for VoIP at ME-3400
> switches ? QoS here is a little different than MLS QoS at
> 3560/3750... All our voice/VoIP traffic is marked with Precedence
> 5.
>
> Robert
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