[Asterisk-Users] Ast 1.0.7, IP-500's with unmanaged switch...remote end missing bits of audio

[Noah Miller]

Hi Marty -

> The complaint from the users is that calls "cut out", "kinda like when
> you have spotty cell coverage". Doesn't seem to matter whether the call
> is incoming or outgoing, although it might be true that my users hear
> the remote party cut out, while the remote party doesn't notice the 
> same
> from my users...
>
> Location 1:
>
> - SDSL 1.5 Mpbs with static IP, Netopia 4652 SDSL router (enabled
> "Prioritize Delay Sensitive Data" to recognize tos=lowdelay per Netopia
> support)
> - Dell PowerEdge SC420 with TDM04B (currently only using one port.  the
> single analog line is call forward on busy to my IAX provider)
> - Asterisk CVS-v1-0-02/22/05 using IAX to connect to my provider over
> the public internet - I have run pings for an extended period of time
> against my provider's server and get no packet loss.
> - In IAX.conf: tos=lowdelay, jitterbuffer=yes, also enabled "Prioritize
> Delay Sensitive Data" on the Netopia to support tos=lowdelay per 
> Netopia
> support
> - Average ping time to my provider: 160 ms with no packet loss
> - 8 Polycom IP-500's running SIP 1.4.1.0040 and bootrom 2.6.1 using 
> ulaw
> only
> - Small Business Server 2003 set up as DC for the network
> - Two network laser printers
> - 24 port unmanaged switch (all phones are home run back to a patch
> panel, patched from there into a switch port.  The DSL modem, printers
> and server are patched into the switch in the same way)
> - 8 pc's running XP Pro, all plugged into the switch port on the back 
> of
> the IP-500's
>
> Location 2:
>
> - Full rate data T1
> - Dell PowerEdge SC1420 with no TDM hardware at all (this location
> connects SIP directly to the T1 providers BroadSoft switch and does not
> go over the public internet)
> - Asterisk 1.0.7 - using SIP to connect with my provider (not across
> public internet, not natted since the Cisco IAD does the SIP mangling
> for us)
> - Average ping time to the broadsoft switch: 42 ms
> - 8 Polycom IP-500's running SIP 1.4.1.0040 and bootrom 2.6.1 using 
> ulaw
> only
> - Small Business Server 2003 set up as DC for the network
> - One network printer
> - 24 port unmanaged switch (all phones are home run back to a patch
> panel, patched from there into a switch port.  The DSL modem, printers
> and server are patched into the switch in the same way)
> - 8 pc's running XP Pro, all plugged into the switch port on the back 
> of
> the IP-500's

I was rather interested to read about the problem you're having.  We 
have a similar setup, and we've been experiencing the same problems.  
We have a Dell PE1600SC in the main office, and SC420's in our remote 
offices.  Main office has a full T1 with a Cisco 1721.  One remote 
office has a full T1 (but we're actually using a DSL backup for IAX 
traffic) with a Cisco 1751, and the other remote office has SHDSL with 
a Linksys.  There are a mixed bag of managed and unmanaged 3Com 
switches, and one office has 3Com hubs.  We are running the same CVS 
HEAD version (CVS-HEAD-04/09/05-08:01:41) on all machines.  I was able 
to mitigate things with a lot of jitterbuffer on the IAX, QoS rules on 
our router, and using our idle backup ISP connections for all the IAX 
traffic.  It is to the point where the sound quality is acceptable, but 
it is not commercial quality - not like Vonage or Broadvoice.  We still 
have drops and pops, and the quality is close to what it should be, but 
the remote IAX connections are NOT as good as the "local" calls on the 
same asterisk box, even though it's all the same codec.

This makes me wonder if perhaps the SC420's are the problem.  I know 
that I had a bit of a problem getting a driver installed for the 
broadcom NIC that is in them.  I think that the linux driver is a very 
recent addition for this chipset.  Do you have any other suspicions?

I did notice that you said you have 160 ms latency between your 
offices.  That is a bit high.  Our is only 20-40 ms between our various 
offices.

Maybe I'll try a different NIC in one of the SC420's.

- Noah