Subject: [Diffserv] Diffserv Complaint in terms of DSCP

From: "amuratt �loglu" <[email-masked]>
Date: Fri, 27 Apr 2001 05:25:09 +0300

In RFC 791 and RFC 1812, it is recommended not to use IP PRE 6 and 7 for 
user traffic ( reserved for internetwork and network control traffic).
Can anyone argueits diffserv compatibility If somebody use 110 or 111 Class 
Selector Code point in defining user data classes.
Plaese send your comments
Ali Iloglu
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From: demir <[email-masked]>
Date: Fri, 27 Apr 2001 01:38:10 -0700 (PDT)

Ali,
Your email has been received more than one time. I think there is
something wrong. You should stop sending the same email to the group.
Answering your question:
Class selector codepoints support legacy use of the IP precedence
field. These codepoints span the TOS field as well as the predecence
field, but the TOS field is not recognized by class seelctor PHB group.
I think there is no restriction on the usage of selectors for user
data. I.e. Default PHB (DSCP: 000000) which is a class selector PHB
corresponding to the lowest level of IP predecence might offer
"best-effort" service for user data. However, all is implementation
dependant. Different implementations might offer differt services for
Class Selector PHB group using various resource allocation mechanisms.
The only requirement is that traffic marked for higher precedence level is
assured a higher or equal probability of forwarding than packets marked
with a lower level precedence level. RFC 2474 gives more on the issue in
detail.

Alper K. Demir