srp521w qos question

Unanswered Question
Oct 25th, 2010

Hello,

I trying out the srp521w smb router and need some quidance configuraing QOS. I have enabled "Bandwidth Control' and added an entry for the voice vlan (priority high), but under QOS status i dont see any stats for the high priority queue. Another thing thats troubling me is that on the router they have a strict priority queue specified, but no place to define what traffic goes in there. we have polycom phones attached to the srp521w. Another weird thing is that i have two polycom's that i'm trying out. One has a pc port on it and the other does not. So the one that does not have an outlet for the pc to plug into gets an ip properly on the voice vlan but the other one which actually has a port for the pc connection comes up with an ip on the defualt vlan.

Thanks for the help in advance.

I have this problem too.
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Andrew Hickman Thu, 10/28/2010 - 00:44

Hi,

For the QoS question, could you let me know what firmware you are using?  Earlier versions of code for the SRP500 did not allow you to specify Strict queuing in a QoS policy defintion.  This is certainly possible in the latest version posted on Cisco.com though.  (Follow download links from www.cisco.com/go/srp500 for the latest release).

For the VLAN question: Do you have CDP enabled on both of your phones?  The SRP uses CDP by default to communicate voice VLAN information - it sounds like one of your phones has this enabled, while the other does not (this one getting an address from the data VLAN).

Hope that helps,

Andy

flyinhorse Tue, 11/09/2010 - 08:12

you were 100% correct on both issues.

Another thing that bothering me is that i cant differentiate between sip and rtp using dscp values. this is extremelu important because these devices will act as trust boundries. Do you know if there is a way to accomplish that. As if now i can only mark all voice traffic with one value.

Thanks,

Aqdas

Andrew Hickman Wed, 11/10/2010 - 06:56

Hi Aqdas,

I'm not sure that I follow the question entirely.

You can use a QoS policy to select all voice traffic originating from, say the voice VLAN and set the queuing priority and marking (remarking really) accordingly.

For example

QoS policy 1 (SIP signalling) - (Note: DSCP 0x80 == CS4)

This selects all traffic to port 5060 from VLAN 100, queues to the High Priority queue and (re)marks to CS4.

SIP.JPG

QoS Policy 2 (Media) - (Note: DSCP 0xb8 == EF)

This selects all UDP traffic using the RTP port range (limit this range if your application does), queues to the strict queue and (re)marks as EF.

media.JPG

Hope this helps,

Andy

flyinhorse Wed, 11/10/2010 - 10:57

I have to say I did'nt look at it that way. No I feel embarassed, thanks for the reply and I believe all my srp questions and concerns are now gone. The only thing I wish cisco would add to this platform or any platform is the ability to capture some packets ( kinda like tcpdump).

Thanks for all your help.

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Posted October 25, 2010 at 8:00 AM
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