Enterprise QoS Solution Reference Network Design Guide
Enterprise QoS Solution Reference Network Design Guide
Enterprise QoS Solution Reference Network Design Guide
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Customer Edge <strong>QoS</strong> <strong>Design</strong> Considerations<br />
5-8<br />
<strong>Enterprise</strong> <strong>QoS</strong> <strong>Solution</strong> <strong>Reference</strong> <strong>Network</strong> <strong>Design</strong> <strong>Guide</strong><br />
Chapter 5 MPLS VPN <strong>QoS</strong> <strong>Design</strong><br />
that the re-marking be performed at the CE’s egress edge, not within the campus. This is because<br />
service-provider service offerings likely will evolve or expand over time, and adjusting to such changes<br />
will be easier to manage if re-marking is performed only at the CE egress edge.<br />
Additionally, in some cases, multiple types of traffic are required to be marked to the same DiffServ code<br />
point value to gain admission to the appropriate queue. For example, on high-speed links, it might be<br />
desired to send Voice, Interactive-Video, and Call-Signaling to the service provider’s Real-Time class.<br />
If this service-provider class admits only DSCP EF and CS5, two of these three applications would be<br />
required to share a common code point. The class-based marking configuration in Example 5-1 shows<br />
how this can be done (in this example, both Interactive-Video and Call-Signaling are re-marked to share<br />
DSCP CS5).<br />
Example 5-1 CE (Egress) <strong>Enterprise</strong>-to-Service Provider Re-Marking Example<br />
!<br />
class-map match-any VOICE<br />
match ip dscp ef<br />
class-map match-all INTERACTIVE-VIDEO<br />
match ip dscp af41<br />
class-map match-any CALL-SIGNALING<br />
match ip dscp af31<br />
match ip dscp cs3<br />
!<br />
policy-map CE-EGRESS-EDGE<br />
class VOICE<br />
priority percent 18<br />
class INTERACTIVE-VIDEO<br />
priority percent 15<br />
set ip dscp cs5 ! Interactive-Video is remarked to CS5<br />
class CALL-SIGNALING<br />
priority percent 2 ! Call-Signaling gets LLQ for this scenario<br />
set ip dscp cs5 ! Call-Signaling is also remarked to CS5<br />
!<br />
!<br />
interface Serial1/0<br />
service-policy output CE-EGRESS-EDGE<br />
!<br />
Verification commands:<br />
show policy<br />
show policy interface<br />
Service providers might re-mark traffic at Layer 3 to indicate whether certain flows are out of contract.<br />
Although this is consistent with DiffServ standards, such as RFC 2597, it might present minor<br />
difficulties to enterprises that require consistent end-to-end Layer 3 marking (typically, for management<br />
or accounting purposes). In such cases, the enterprise can choose to apply re-marking policies as traffic<br />
is received back from the service provider’s MPLS VPN (on the ingress direction of the enterprise’s CE).<br />
Class-based marking can be used again because it supports not only access lists for classification, but<br />
also <strong>Network</strong>-Based Application Recognition (NBAR).<br />
Continuing and expanding on the previous example, the enterprise wants to restore the original markings<br />
that it set for Interactive-Video and Call-Signaling. Additionally, it wants to restore original markings<br />
for Oracle traffic (which it originally marked DSCP 25 and is using TCP port 9000 with) and DLSw+<br />
traffic (originally marked AF21). Both of these data applications were handed off to the service provider<br />
marked as AF21, but they might have been marked down to AF22 within the service-provider cloud.<br />
Example 5-2 shows a configuration that enables such re-marking from the MPLS VPN. The “match-all”<br />
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