Cisco CRS-1 - Carrier Routing System Router Migration Guide

3-76
Cisco CRS-1 Carrier Routing System to Cisco CRS-3 Carrier Routing System Migration Guide
OL-13669-03
Chapter 3 Cisco CRS-3 Carrier Routing System Router Command Changes
QoS Features Changes
QoS Features Changes
General
• Layer 2 VPN QoS features are not supported.
• Cisco CRS Series Modular Services Card 140G (CRS-MSC-140G) uses "layer-all" accounting. For
Ethernet interfaces, this translates to 20 bytes of Layer 1 overhead in addition to the Layer 2
overhead. Cisco CRS Series Modular Services Card 40G (CRS-MSC-40G) does Layer 3 QoS
accounting for ingress queueing. CRS-MSC-40G does Layer 2 QoS accounting for egress queueing,
egress policing, and ingress policing.
Queueing
Changes Common to Ingress and Egress Queuing
• High priority traffic under all ports and groups is serviced before any low priority traffic. This means
that the scope of priority assignment at the queue level is global - it is not limited to the parent group
(such as on CRS-MSC-40G) or port. This is referred to as high priority propagation, which improves
low latency treatment for high priority traffic, such as real-time voice and video traffic.
• Priority assignment at the group level for an egress interface policy is not supported.
• A policer must be configured to limit the traffic entering priority queues.
Ingress Queuing Only
• Maximum number of ingress queues and groups (or virtual ports) on each line card:
– 49,152 low priority queues
– 16,384 virtual high priority queues (up to 1 under each virtual port - same as for
CRS-MSC-40G)
– 16,384 groups or virtual ports
• Smallest step size supported is 32 kbps for groups and 32/3 kbps (10.67 kbps) for queues. Step size
increases with the rate value. Rounding error does not exceed 0.4 per cent or 8 kbps, whichever is
higher.
Egress Queuing Only
• Maximum number of egress queues and groups on each line card:
– 65,536 queues, of which up to 16,384 can be high priority queues
– Up to 1 high priority queue per level under each group (same as for CRS-MSC-40G)
– 16,384 groups
– Two high priority levels are supported.

Cisco CRS-1 - Carrier Routing System Router Specifications

General

Brand	Cisco
Model	CRS-1 - Carrier Routing System Router
Category	Network Router
Language	English