Nortel 4524GT Configuration page 31

"Default QoS fields by class of interface--IPv4 only" (page 31)
default guidelines the switch uses to re-mark various fields of IPv4 traffic
(and layer 2 traffic matching IPv4) based on the class of the interface.
These actions occur if the user does not intervene at all; they are the default
actions of the switch.
Default QoS fields by class of interface--IPv4 only
Type of filter Action
IPv4 filter DSCP
criteria or
Layer 2
filter criteria
matching IPv4
IEEE 802.1
p
The default for layer 2 non-IP traffic is to pass the traffic through all interfaces
classes with the QoS values for 802.1p and drop precedence unchanged.
The Nortel Ethernet Routing Switch 4500 Series does not trust the DSCP of
IPv4 traffic received from an untrusted port, however, it does trust the DSCP
of IPv4 traffic received from a trusted port.
L2 non-IP traffic, received on either a trusted port or an untrusted port,
traverses the switch with no change.
IPv4 traffic, received on a trusted port, has the 802.1p user priority value
re-marked and the drop precedence set, based on the DSCP in the received
IP packet.
If an IPv4 packet is received from a trusted port, and either it does not match
any of the classifier elements installed by the user on this port or it does
match a classifier element but is not dropped, the Nortel Ethernet Routing
Switch 4500 Series uses default system classifiers to change the packet
IEEE 802.1p and drop precedence based on the DSCP of the packet.
Copyright © 2007, Nortel Networks
.
The 802.1p user priority value is updated based on the DSCP-to-CoS
mapping data associated with the best effort DSCP, which is 0.
Trusted
Does not
change
Updates based
on DSCP
mapping table
value
Nortel Ethernet Routing Switch 4500 Series
Configuration — Quality of Service
NN47205-504 (322816-B)
5.1 23 November 2007
Trusted, untrusted, and unrestricted interfaces 31
Untrusted
• Tagged--Updates to 0
(Standard)
• Untagged--Updates using
mapping table and port's
default value
Updates based on DSCP
mapping table value
ATTENTION
03.01 Standard
shows the
Unrestricted
Does not
change
Does not
change