Enterprise QoS Solution Reference Network Design Guide

Customer Edge QoS Design Considerations
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Enterprise QoS Solution Reference Network Design Guide
Chapter 5 MPLS VPN QoS Design
that the re-marking be performed at the CE’s egress edge, not within the campus. This is because
service-provider service offerings likely will evolve or expand over time, and adjusting to such changes
will be easier to manage if re-marking is performed only at the CE egress edge.
Additionally, in some cases, multiple types of traffic are required to be marked to the same DiffServ code
point value to gain admission to the appropriate queue. For example, on high-speed links, it might be
desired to send Voice, Interactive-Video, and Call-Signaling to the service provider’s Real-Time class.
If this service-provider class admits only DSCP EF and CS5, two of these three applications would be
required to share a common code point. The class-based marking configuration in Example 5-1 shows
how this can be done (in this example, both Interactive-Video and Call-Signaling are re-marked to share
DSCP CS5).
Example 5-1 CE (Egress) Enterprise-to-Service Provider Re-Marking Example
!
class-map match-any VOICE
match ip dscp ef
class-map match-all INTERACTIVE-VIDEO
match ip dscp af41
class-map match-any CALL-SIGNALING
match ip dscp af31
match ip dscp cs3
!
policy-map CE-EGRESS-EDGE
class VOICE
priority percent 18
class INTERACTIVE-VIDEO
priority percent 15
set ip dscp cs5 ! Interactive-Video is remarked to CS5
class CALL-SIGNALING
priority percent 2 ! Call-Signaling gets LLQ for this scenario
set ip dscp cs5 ! Call-Signaling is also remarked to CS5
!
!
interface Serial1/0
service-policy output CE-EGRESS-EDGE
!
Verification commands:
show policy
show policy interface
Service providers might re-mark traffic at Layer 3 to indicate whether certain flows are out of contract.
Although this is consistent with DiffServ standards, such as RFC 2597, it might present minor
difficulties to enterprises that require consistent end-to-end Layer 3 marking (typically, for management
or accounting purposes). In such cases, the enterprise can choose to apply re-marking policies as traffic
is received back from the service provider’s MPLS VPN (on the ingress direction of the enterprise’s CE).
Class-based marking can be used again because it supports not only access lists for classification, but
also Network-Based Application Recognition (NBAR).
Continuing and expanding on the previous example, the enterprise wants to restore the original markings
that it set for Interactive-Video and Call-Signaling. Additionally, it wants to restore original markings
for Oracle traffic (which it originally marked DSCP 25 and is using TCP port 9000 with) and DLSw+
traffic (originally marked AF21). Both of these data applications were handed off to the service provider
marked as AF21, but they might have been marked down to AF22 within the service-provider cloud.
Example 5-2 shows a configuration that enables such re-marking from the MPLS VPN. The “match-all”
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