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New Member

Fixing QOS on network - need help

Let's me just start by saying QOS is new to me.  I've never had to deal with it before.  I've been slowly upgrading the company's network, making a lot of changes.  My predecessors had made some forays into CoS to prioritize voice traffic on the old switches, and I need to get it straigtened out as we seem to be encountering some quality issues.

The company has two different voice products that it uses.  VLAN 6, labeled SIP, utilizes SIP based hosted stations.  The host they connect to is outside the network.  VLAN 8, labeled VOIP, is internal to the company, connecting to an Avaya PBX with VIOP capabilities.  Each VLAN has a different private subnet, and both route through a 3750G stack set up to be the core.  I have ASAs at the edge.  In addition to the corporate office, we have a secondary site interconnected by a pair of fiber runs (etherchannel, different routes for redundancy).  These two sites are on a flat network.  That is to say, they both share the same vlans, subnets, etc.  Traffic is not routed between them.  We also have a half-dozen remote sites, also connected via fiber links, but those have their own subnets/vlans and are routed through a single subnet with OSPF.

To further complicate things, most of the access switches in use are HP ProCurve switches.  One or two of them have qos priority settings on the VLAN interfaces.  I'm also told that the SIP phones are set to transmit with DSCP values (I'm currently trying to find out from the SIP team what value that is).

I've been doing a lot of reading, and I will admit a lot of it goes over my head.  I'm looking for help to get the network properly prioritizing the voice traffic througout.  I've attached a logical network diagram - please note that it does not show the HP ProCurve access switches.  Most of the HP switches at the HQ are hanging off a single 5308 connected to the 3750 core switch stack.  At the secondary location, most of them are on the 3750 stack directly. 

I look forward to your input.

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5 REPLIES
Cisco Employee

Fixing QOS on network - need help

Wow.. you got a world of different vendors connected together

I would point you to the Medianet QOS campus design guide which will come handy to plan for QOS depolyment on your 3750 switches.

http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND_40/QoSCampus_40.html

Hope this helps.

New Member

Fixing QOS on network - need help

Thanks.  I will review it.  In the mean time, a question:  From what I've read, the auto qos feature appears to mainly be designed for Cisco equipment.  Can auto qos be used with Avaya voip or Polycom hosted stations?

Fixing QOS on network - need help

Yes.. Auto qos be used with Avaya voip or Polycom hosted stations. We did the same in our infra. Cisco POE switches with auto QOS enabled - still using kind of old model 4625 IPphones and 4690 conf units. No issues so far.

Hth

MS

New Member

Fixing QOS on network - need help

Campus design guide is still a bit over my head...

In terms of the Auto QoS and my etherchannels - it  doesn't look like I can set auto qos trust dscp on the inteferfaces that  are port channel members.  Should I use mls qos trust dscp instead?   Most of the switches are interconnected to the core stacks with  etherchanneled links for redundancy purposes - I need to make sure the  QoS values follow through.

New Member

Fixing QOS on network - need help

Finally heard back from the SIP guy.  He says the phones are set as follows:

  • Signaling; DSCP = 0X1a: Assured Forwarding 31, TOS = 0X68
  • RTP; DSCP = 0X2e: Expedited Forwarding, TOS=0X68
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