It depends on which version of IOS you are running. Starting around 12.2(8)T, the following commands allowed you to specify the RTP and signaling traffic QOS marking under the voip dial-peers separately:
ip qos dscp xxx signaling
ip qos dscp xxx media
(where xxx is the dscp value)
Typically, DSCP marking should be EF for media (RTP) and CS3 for signaling (in past marking for signaling was AF31 for DSCP, however there has been a shift to CS3 for signaling recently).
To see what the marking is for a particular dial-peer, use the following command:
show dial-peer voice ###
(where ### is the number of the voip dial-peer you want to look at).
Check out the values for "ip media DSCP" and "ip signaling DSCP", these will be the marking for the respective traffic.
This is all dependent on the version of IOS and earlier versions of IOS may not provide the ability to adjust packet marking for both media and signaling and typically an IP precedence value set on a dial peer on early versions of IOS applied only to the media stream only.
Without out going into a whole lot of detail, basically it comes down to this:
RFC 2597 defines the assured forwarding (AF) classes. There are four AF classes, AF1x through AF4x. Within each class, there are three drop probabilities. These drop policies are low, medium, and high. AF31 incidently falls in the low drop probablity group. From a QOS perspective, sending traffic such as voice signaling (which is critical to voice media) with a marking that might result in it being dropped (albiet the chances are low) is a bad idea. Instead by sending signaling at DSCP CS3, we've eliminated the whole drop probability associated with the Assured Forwarding DSCP marking. This isn't to say that these packets can't or won't be dropped, it's just not a built in mechanism.
The short answer is that you don't.... That isn't entirely true while at
the same time it kind of is, but for the most part you don't configure
the softkeys. You enable or disable them via TCL. Here is the long
answer. Be sure to read the whole thing or e...
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This document describe how DST changes and how time changes are
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