Queue Limit - Cisco 10000 Series Configuration Manual

Queue Limit

In Cisco IOS Release 12.3(7)XI2, the subinterfaces on a given main interface share the single system
queue of the main interface. This allows for 32,000 subinterfaces with a three-queue model that supports
assured forwarding (AF) queues, expedited forwarding (EF) queues, and the default best effort (BE)
queues. Because a system queue is not allocated for every subinterface, queues are freed up for a
four-queue model.
Table 11-1
Table 11-1 Queue Scaling Limits
Queue Criteria
Total Number of Queues Per
1
System
No. Queues Per Link
Total Number of Packet
4
Buffers for Queue Depth
1. Includes network-control and default queues.
2. 29 user-configurable queues, 1 class-default queue, 1 system queue, and 1 reserved queue
3. 14 user-configurable queues, 1 class-default queue, 1 system queue
4. With 131,070 queues configured, the average queue limit across all of the configured queues is less than or equal to 32 packets per queue: 4,194,304
divided by 131,070 equals 32.
5. The PRE3 implements queues in such a way that this limit no longer exists.
Queue Limit
Each queue has a limit on the number of packets that the router can place onto the queue. This limit,
referred to as the depth, is a user-configurable limit. During periods of high traffic, a queue fills with
packets waiting for transmission. When a queue reaches its queue limit and becomes full, by default the
router drops packets until the queue is no longer full.
Table 11-2
Cisco 10000 Series Router Quality of Service Configuration Guide
11-2
lists the scaling limits for class queues.
PRE3
Release 12.2(31)SB2 or later
256,000
15
5
Not Applicable
describes the queuing limits for the various processor cards.
Chapter 11
PRE2 PRE2
Release 12.3(7)XI or later Release 12.2(16)BX or later
131,070 65,534
2
32 32
4,194,304 4,194,304
Managing Packet Queue Congestion
PRE1
32,766
3
16
1,048,576
OL-7433-09