qos for video and voice

[simsim]

HI,

I am using cisco expressway (sip and  h323),What is the recommendation for qos 

Thanks

[OtakarKlier]

Hello,

The answer is it depends. It depends on how much bandwidth is between the sites. How much of that traffic is voice/video. and what you are comfortable with.

i.e. lets say you have 100M between sites and only see usage of about 10-15 megs of voice/video. In this case I would probably set my QoS to be 25% (just my 2 cents) of the total bandwidth. This would allow for spikes in traffic and still give a small buffer.

Just remember that youre not saving that bandwidth, i.e. not usuable for anything other than voice/video. All its saying is that if there is voice/video, give it priority upto 25% of the 100M.

https://live.paloaltonetworks.com/t5/Featured-Articles/Getting-Started-Quality-of-Service/ta-p/68633

I look at it as a moving target rather than a set and forget it setting. 

Hope that helps.

[fjwcash]

We use QoS for prioritisation of packets, rather than limiting/guaranteeing bandwidth.

By default, all traffic is put into Class 4 on the firewall.  Then we have two QoS Profiles:

  - one that matches SIP traffic that we put into Class 2

  - one that matches RTP/RTSP traffic that we put into Class 1

That way, all traffic is delivered in a first-come/first-served manner ... until there's network congestion. At that point, RTP/RTSP traffic gets sent out first, STP traffic gets sent out next, and everything else is sent when there's room.

All of the firewalls in our WAN are configured the same, with MPLS or direct fibre links connecting them back to the central firewall.  That handles sending the traffic out from the firewalls.

On the LAN side of things, we use DSCP in our VoIP/videoconferencing systems (af for SIP traffic, ef for RTP/RTSP traffic) with all the switches configured to respect DSCP tags.  And we have the Security Profiles on the firewalls configured to set the DSCP tag for SIP/RTP/RTSP traffic.

The only issue we ran into was the 1 Gbps limit for interfaces with QoS enabled, regardless of what the interface could actually handle.  We had a 2 Gbps LACP interface (using two 1 Gbps physical interfaces) that was being limited to 1 Gbps because we had enabled QoS on it.  This was fixed in PanOS 7.1.11 ... we were running 7.1.10.  🙂  We've since upgraded and re-enabled QoS on the LACP interface and no longer have that limit.

VoIP/videoconferencing traffic has been working nicely with the above setup.  Not sure if it's "the perfect setup", but it's working for us.  🙂  Always open to suggestions, though.  😄