Medianet Reference Guide - Cisco

Cisco Network Analysis Module
Chapter 6
Medianet Management and Visibility Design Considerations
control and therefore the protection of service classes. When multiple service classes are mapped to a
single queue, separate drop thresholds can be implemented (on platforms that support them) to provide
differentiation of service classes within the queue. The implementation of queueing and drop thresholds
is viewed as necessary to provide the correct per-hop treatment of the video application traffic to meet
the overall desired service levels of latency, jitter, and packet loss across the medianet infrastructure. An
example of the mapping of service classes to egress queueing on a Cisco Catalyst 6500
WS-X6704-10GE line card, which has a 1P7Q8T egress queueing structure, as shown in Figure 6-22.
Note that the percentage of bandwidth allocated per queue depends on the customer environment;
Figure 6-22 shows only an example.
Figure 6-22 Example Mapping of Service Classes to Egress Queueing on a Cisco Catalyst 6500
Line Card with 1P7Q8T Structure
Application
DSCP
1P7Q4T
Network Control
(CS7)
EF
Q8 (PQ)
Internetwork Control
Voice
Multimedia Conferencing
TelePresence
Multimedia Streaming
Call Signaling
CS6
EF
AF4
CS4
AF3
CS3
CS4
CS7
CS6
CS3
CS2
AF4
Q7 (10%)
Q6 (10%)
Q5 (10%)
Q6T4
Q6T3
Q6T2
Q6T1
Transactional Data
AF2
AF3
Q4 (10%)
Network Management
CS2
AF2
Q3 (10%)
Bulk Data
Best Scavenger Effort
Best Effort
AF1
CS1 DF
DF
DF/0
AF1
CS1
Q2 (25%)
Q1 (5%)
Q1T2
Q1T1
228433
This QoS methodology can also provide enhanced visibility into the amount of traffic from individual
video application types crossing points within the medianet infrastructure. The more granular the
mapping of individual video applications to service classes that are then mapped to ingress and egress
queues, the more granular the visibility into the amount of traffic generated by particular video
applications. You can also gain additional visibility into troubleshooting video quality issues caused by
drops within individual queues on router and switch platforms.
The following high-level methodology can be useful for troubleshooting video performance issues using
the router and switch CLI. As with anything, this methodology is not perfect. Some of the shortcomings
of the methodology are discussed in the sections that cover the individual CLI commands. However, it
can often be used to quickly identify the point within the network infrastructure where video quality
issues are occurring. The steps are as follows:
1. Determine the Layer 3 hop-by-hop path of the particular video application across the medianet
infrastructure from end-to-end, starting from the Layer 3 device closest to one end of the video
session. The traceroute CLI utility can be used for this function.
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Medianet Reference Guide
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