[c-nsp] strange RTT increase in ASR1006

Nick Hilliard nick at foobar.org
Sat Feb 2 18:07:29 EST 2013

On 02/02/2013 11:33, Tassos Chatzithomaoglou wrote:
> The same happens in the following scenario on another ASR1006 (RP2/ESP20/SIP10); when the
> output of Te1/1/0 goes above 6G, RTT for packets flowing from Te1/0/0to router's loopback
> increases by 50-100ms (RP is at ~30% all the time).
>                    +-----+
> Te1/0/0 (6G/1G) ---|     |---Te1/1/0 (1G/6G)
>                    |     |
>                    |     |
>                    +-----+

Whatever about the problems which are occurring with the esp40 + the 3x10G
interfaces, an ESP20 should easily be able to handle 7G (=6G+1G) of simple
in/out traffic without sweating.  Microbursts cannot explain this scenario
because you cannot burst higher than 10G line rate ingress on either side.
 So if there is buffering followed by packet loss and if the box is issuing
internal flow control signals, that suggests something very peculiar is
going on.

Have you come across this document:

> http://www.cisco.com/en/US/products/ps9343/products_tech_note09186a0080af2d14.shtml

It should show you where the packets are being dropped (e.g. spa, sip or


More information about the cisco-nsp mailing list