[cisco-voip] QoS DSCP Markings for voice signaling - Which is right?

[Linsemier, Matthew]

All,

Over the past few weeks I have been working on reconfiguring our LAN and
WAN QoS markings in preparation for  a future upgrade to MPLS.  During
this time I have noticed several inconsistencies in regards to what DSCP
markings should be utilized (or are being utilized) for voice signaling
traffic.

 

The SRND clearly states that all voice traffic should be marked DSCP EF
and voice signaling traffic should be marked as DSCP CS3.  The old
method was marking voice signaling traffic with AF31.

 

 Here is where things get confusing:

 

*         The latest versions of AutoQoS on Catalyst 3550 and Catalyst
3750 switches map COS3 as AF31.  I believe that AutoQoS run on a router
serial port does the same.

*         The latest version of QPM 4.0 (I downloaded the evaluation)
follows AutoQoS settings on those switches that support it and changes
the settings on Catalyst 6500's running CatIOS to map COS3 to AF31.

*         An engineer on a recent TAC case that I had opened in regards
to QoS on the Catalyst 6500 recommended that the mapping of COS3 be
changed to AF31.

One would think that AutoQoS, QPM 4.0, and TAC should all be on the same
page and abide by the settings within the SRND if they are correct, but
they don't.  Does anyone know why this is?  Shouldn't AutoQoS and QPM
4.0 be based off of the SRND?

 

While I know it is easy to match on both CS3 and AF31, since I am
already rewriting my policy from scratch, my intentions are to carry one
marking for the voice signaling traffic across my LAN/WAN.  Because
several applications such as CalLManager already mark voice signaling as
CS3 by default, unless anyone tells me otherwise, this is the setting I
plan on using and will adjust the AutoQoS and COS mappings accordingly.

 

Your input would be greatly appreciated.

 

Thanks,

 

Matt

 

 

 


CONFIDENTIALITY STATEMENT
This communication and any attachments are CONFIDENTIAL and may
be protected by one or more legal privileges. It is intended
solely for the use of the addressee identified above. If you
are not the intended recipient, any use, disclosure, copying
or distribution of this communication is UNAUTHORIZED. Neither
this information block, the typed name of the sender, nor
anything else in this message is intended to constitute an
electronic signature unless a specific statement to the
contrary is included in this message. If you have received this
communication in error, please immediately contact me and delete
this communication from your computer. Thank you.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://puck.nether.net/pipermail/cisco-voip/attachments/20070625/6fa589d7/attachment.html