Cisco 10000 Series User Manual

19-3
Cisco 10000 Series Router Quality of Service Configuration Guide
OL-7433-09
Chapter 19 Configuring Quality of Service for PVC Bundles
PVC Bundles
Note IP precedence and MPLS EXP have eight levels that you can assign and DSCP has 64 levels. To include
all DSCP values, you can assign a range of DSCP values (for example, 9-16) to a particular DLCI and
assign the remaining DSCP values to another DLCI using the dscp other command.
Traffic Bumping
Traffic bumping provides a way to keep a PVC bundle up and traffic flowing even though some
individual PVCs might be down. You can configure each PVC bundle member to bump traffic to another
PVC in the bundle when the bundle member does down. You can also specify that a particular PVC can
never accept bumped traffic from another PVC. The default is to accept bumped traffic.
You can specify traffic bumping as either implicit or explicit bumping. Implicit bumping diverts the
traffic from a failed PVC to the PVC having the next lower service level. Explicit bumping forces the
traffic to a specific PVC rather than allowing it to find a PVC carrying traffic of the next lower service
level. The default is to perform implicit traffic bumping.
For example, consider a sample configuration with two PVCs: PVC1 and PVC2. You configure PVC1
to carry precedence level 3 traffic, PVC2 to accept bumped traffic and to carry precedence level 6 traffic,
and PVC1 to bump its traffic to PVC2. If PVC1 goes down, the following occurs:
• PVC2 takes over.
• If PVC2 is already down or goes down later, the router selects an alternate PVC based on the
bumping rule for PVC2.
• If the router cannot find an alternate PVC for the bumped traffic, the entire PVC bundle goes down.
If a bundle member allows PVC bumping, the router selects the next lower precedence level PVC when
a PVC goes down. You can specify only one precedence level for bumping. If the PVC that carries the
bumped traffic fails, the router applies the bumping rules specified for the failed PVC to the traffic. When
the original PVC is up again, the router restores traffic to the original PVC.
PVC Bundle Protection Rules
PVC bundle protection rules provide a way to force the PVC bundle down even though some individual
PVCs are up and might be able to handle all of the traffic, though perhaps not in a satisfactory manner.
The protection rules add flexibility for controlling the state of the PVC bundle.
You can configure a PVC bundle member as an individually protected PVC or as part of a PVC bundle
protected group. Only one protected group can exist within a PVC bundle; however, many individually
protected PVCs can exist.
When a bundle goes down, the router cannot forward traffic using the bundle, even if some of the PVCs
in the bundle are still up. The entire bundle goes down when:
• One individually protected PVC goes down
• All of the PVCs in a protected group go down.
If you do not specify a protection rule, the PVC bundle goes down only when all of the PVCs go down.
However, if a PVC that has no place to bump its traffic goes down, the router brings down the entire
bundle despite any protection rules that have been set up.

Cisco 10000 Series Specifications

General

Brand	Cisco
Model	10000 Series
Category	Network Router
Language	English