[Asterisk-Users] FWIW- Cisco 1750 dropped packets and choppy audio

[Adam Goryachev]

On Thu, 2004-06-10 at 23:27, Rich Adamson wrote:
> This email is intended to document an issue for anyone searching the archives.
> 
> We had a problem yesterday with _all_ iax2 and sip sessions; no reasonable
> conversation could be established due to extremely choppy audio in one
> direction only (outbound from * to distant sip phones and distant * boxes).
> We were running HEAD from June 8th.
> 
> While diagnosing the root cause, we monitored bandwidth utilization at the
> asterisk-connected managed-switch as well as at the Cisco 1750 Internet
> interface. We observed consistent/even data flows to/from the * box, however
> the outbound Cisco interface indicated more inbound traffic than outbound
> traffic by a considerable/noticeable amount. Both iax2 and sip sessions were 
> impacted exactly the same regardless of the codec being used.
> 
> In the haste to identify the root-cause, the Cisco 1750 was rebooted
> (Version 12.2(4)T7) and the problem disappeared. A Service-Policy had been
> applied to the outbound interface for QoS purposes. Removing the policy
> while a poor quality session was in progress had zero impact. Unfortunitly, 
> no other Cisco data was gathered before the reboot. We're waiting for
> reoccurrence to gather additional doc. We are 100% confident this is a
> Cisco issue as opposed to * or any other resource. (Someone, maybe Eric, 
> mentioned a Cisco QoS bug previously on this list. Indications are this 
> might be the bug that person had mentioned.)
> 
> The Cisco had been in use for a couple of years and we've never seen this
> issue arise prior to yesterday. The * box had been in semi-production since
> late last year and has been stable (given the expected issues associated
> with using HEAD as opposed to Stable).
> 
> There were no logged messages from the Cisco even though syslog messages are
> normally monitored closely.

This may or may not be related, I have a Cisco 8xx (something, ADSL
router) and had very poor audio in both directions, I was seeing very
large number of packets/sec in both directions. I solved it by turning
off all the debugging on the cisco. (I had debug ip packet turned on for
packets matching a specific access-list).

As a side note, I first noticed the CPU load on the cisco sitting on
100% during an attempted phone call.

Re-booting your router would have also disabled all debugging, but that
may not have been your issue, it is difficult to say.

Hope this helps someone else go DoH! like I did :)

Regards,
Adam