[c-nsp] low throughput of 10GbE line

[Peter Rathlev]

On Mon, 2010-03-15 at 17:26 +0100, Jirí Procházka wrote:
> Catalyst 7606 ( IOS 12.2(33)SRD4) with WS-F6700-DFC3CXL module
> connected with C3750-E (IOS 12.2(40)SE) over TenGigabit Xenpaks. Its
> one of our backbone lines, transferring only VLAN-201.

>From the use of XenPack I assume the module is a WS-X6704-10GE.

> sitel-edge-new#show int te4/8
> TenGigabitEthernet4/8 is up, line protocol is up (connected)
[...]
>   Input queue: 0/4096/96151289/0 (size/max/drops/flushes); Total
> output drops: 0
>   Queueing strategy: fifo
>   Output queue: 0/4096 (size/max)
>   30 second input rate 4942942000 bits/sec, 410813 packets/sec
>   30 second output rate 143433000 bits/sec, 241176 packets/sec
>      34434311308 packets input, 51018973201607 bytes, 0 no buffer
>      Received 21472 broadcasts (17607 multicasts)
>      0 runts, 0 giants, 0 throttles
>      0 input errors, 0 CRC, 0 frame, 96151289 overrun, 0 ignored
>      0 watchdog, 0 multicast, 0 pause input
>      0 input packets with dribble condition detected
>      19623750753 packets output, 3094225873410 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

Input overrun would mean that the card is unable to receive the traffic
it's served. The 6704 only has 2 MB input buffers, so there isn't much
room.

You would have better luck with a WS-X6708-10G. It has 109 MB input
buffers. They come with a "free" DFC3C by the way.

Other than increasing the input buffer size (a hardware parameter)
there's nothing much to do about it, apart from making sure the traffic
is extremely non-bursty.

-- 
Peter