6-11
Cisco AVVID Network Infrastructure Enterprise Quality of Service Design
956467
Chapter 6 QoS with MPLS in an AVVID-Enabled Network
Implementing MPLS VPN QoS
Table 6-1
Mapping of EXP Values to Virtual Circuits
Within an ATM network that is not MPLS enabled, each ATM permanent virtual circuit looks like a
point-to-point connection to the MPLS nodes. Given that, each node must apply a per-virtual circuit
mechanism, such as CBWFQ, in order to enforce QoS. One option that can be used, but which inherently
does not scale, is to rate-limit the egress interfaces of the CE routers. This ensures that the MPLS
backbone network, which is ATM, cannot be over-subscribed. This is difficult enough to ensure in a
steady-state condition, but under failure within the ATM network, a mechanism must be used to ensure
that no PVCs are re-routed to a link that would cause over-subscription.
shows the configuration of a PE router.
In this example, the PE router uses a policer to check the inbound traffic from the customer CE router
and sets the MPLS EXP bits based on whether the traffic is in conformance with the service contract, as
agreed to by the customer and SP. The commands to implement QoS are highlighted in bold.
Example 6-2
PE Router Configuration
version 12.0
ip cef distributed
no ip finger
no ip domain-lookup
!
class-map match-all VOICE-MPLS
match mpls experimental 5
class-map match-all DATA-MPLS
match mpls experimental 1 2
class-map match-all VOICE-DSCP
match ip dscp ef
class-map match-all DATA-DSCP
match ip dscp af31 af21 af22 af23 af11 af12 af13
!
!
policy-map PE-EDGE-IN
class VOICE-DSCP
police 1280000 32000 32000 conform-action
set-mpls-exp-transmit 5 exceed-action drop
class DATA_DSCP
police 22000000 550000 550000 conform-action
set-mpls-exp-transmit 2
exceed-action set-mpls-exp-transmit 1
class class-default
set mpls experimental 0
!
!
MPLS EXP Value
VC
0
Available
1
Standard
2
Premium
3
Control
4
Available
5
Standard
6
Premium
7
Control