Extreme Networks ExtremeWare 7.3.0, Command Reference Manual

Page: 1690 / 2254

1690 ExtremeWare Software 7.3.0 Command Reference Guide
PoS Commands
unconfigure diffserv dscp-mapping ports
unconfigure diffserv dscp-mapping ports <portlist>
Description
Resets the DSCP mapping tables for the specified PoS ports to their default values.
Syntax Description
Default
N/A.
Usage Guidelines
Three DSCP mapping tables are supported per SONET port. One of the tables is used in the ingress
direction and two are used for egress flows (onto the SONET link). The two egress tables are for the
congested and non-congested states, as determined by the RED algorithm (in other words, the
congested state is when the average queue length is greater than the minimum RED threshold). If RED
is not enabled on the SONET port, then the egress congested-state mapping table is not used.
The tables are very simple. In the ingress direction, the input DSCP of a packet received from the
SONET link is replaced with an output DSCP before the packet is forwarded. The replacement is
straightforward; the input DSCP is used as an index into a 64-entry table that contains the output
DSCPs associated with each of the input DSCP values. The operation is similar in the egress direction,
with the DSCP mapping occurring before the packet is transmitted onto the SONET link(s). The
mapping operation is performed after the packet has been assigned to a QoS profile. One potential use
of the DSCP mapping capability is reconciliation of varying DiffServ policies at the boundary between
autonomous systems (for example, at the boundary between two ISPs). The availability of different
tables for the congested/non-congested states is useful for marking operations that increase the drop
probability of packets during times of congestion, as discussed in the DiffServ assured forwarding (AF)
RFC.
This command is currently only applicable to SONET ports.
Example
The following command resets the DSCP mapping tables for port 1, slot 8 of a BlackDiamond switch to
their default values:
unconfigure diffserv dscp-mapping port 8:1
History
This command was first available in an ExtremeWare IP Technology Services Release based on
v6.1.5b20.
portlist Specifies the port number(s).