Multiclass MLP Support on the Cisco PRE3/PRE4

Transcription

1 Multiclass MLP Support on the Cisco PRE3/PRE4 First Published: August 2008 This document describes the Multiclass MLP Support on the Cisco Series Router PRE3/PRE4 feature. In releases prior to, MC-MLP is supported on the Cisco series router PRE2 platform and you can configure up to 4 multi classes. However, MC-MLP implementation includes the following limitations: 1. You cannot configure encap-sequences for priority queues. Therefore, only interleaving fragments of low-priority packets are queued. 2. After the priority queue is configured, priority packets are interleaved with low-priority packets using the turbo-lfi mechanism. 3. Only one level of priority exists. Due to these limitations, high-priority packets are sent out of sequence in a multilink bundle with more than one member link. Because the MLP bundle carries different types of traffic, new user applications require an intermediate priority level (for example, VOIP traffic and CDMA 3G-1X traffic on same MLP bundle). The PRE2 MC-MLP feature does not support classifying traffic with more than one priority level and interleaving fragments between priority and nonpriority classes to achieve better delay and jitter for intermediate priority classes. For PRE3 and PRE4, the Hierarchical Queuing Framework (HQF) infrastructure allows you to configure two levels of priority queues and strict priority scheduling between the priority queues so that the priority queue fragments can be interleaved. Also, you can attach a priority queue to a specific multiclass. Therefore, you can send traffic that is expected to be resequenced using the MC-MLP header. History for the Multiclass MLP Support Feature Release 12.2(34)SB Modification This feature was introduced on the Cisco series router for the Performance Routing Engine 3 (PRE3) and PRE4. Finding Support Information for Platforms and Cisco IOS Software Images Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions. 1

2 Contents Contents Prerequisites for Multiclass MLP Support, page 2 Feature Overview, page 2 Restrictions on Multiclass MLP Support, page 2 Configuring Multiclass MLP Support, page 3 Configuration Example, page 4 Verifying Multiclass MLP Support, page 4 Additional References, page 5 Prerequisites for Multiclass MLP Support In, Multiclass MLP support on the Cisco Series Router PRE3/PRE4 has the following prerequisites: A policy-map specifying an encap-sequence mlp_class_id must have a queue action associated with the class such as priority, bandwidth, or shape. Each output queue can only have one mlp_class_id associated. If the MLP bundle is not configured with multiclass support, then encap-sequence configuration is not allowed on the policy attached to the MLP bundle. Priority and encap-sequence configurations cannot be overwritten. You must remove previous priorities and encap-sequences before configuring new value. Feature Overview In releases prior to Cisco IOS Release 12.2(33)SB, the number of MLP bundles in the Cisco series router was limited to This limitation was due to VCCI numbering space and the number of reassembly tables available in Cobalt memory.in Cisco IOS Release 12.2(33)SB, the MLPoLNS feature redefined the VCCI numbering scheme and increased the VCCI range for MLP bundles from 2511 to Also, the MLPoLNS feature started using XCM reassembly tables to support more MLP bundles. The limitation imposed by the MLPoLNS feature is that Cobalt reassembly tables are used for multimember MLP bundles and XCM reassembly tables are used for single-member MLP bundles. In, the XCM reassembly tables are available for multimember bundles as well as multimember MLP bundles. Restrictions on Multiclass MLP Support In, multiclass MLP support on the Cisco series router PRE3/PRE4 is implemented as per RFC 2686 with the following restrictions: MC-MLP is supported only on serial interfaces with PPP encapsulation in an MLPPP bundle. It is not supported on any ATM VCs that are in an MLPoA bundle, LFIoA bundle, or MLPoFR encapsulated serial interface. 2

3 Configuring Multiclass MLP Support If MC-MLP is enabled on the bundle and encap-sequence is not configured, an MC-MLP bundle has an encap-sequence of zero by default. For PRE4, the maximum number for mlp_class_id is 16 classes per bundle, depending on the platform. For PRE 3, the maximum number is 4. The encap-sequence none command is allowed only in a priority level 1 class. When an encap-sequence is shared by multiple classes, interleaving is not performed for those classes. Interleaving is allowed for priority level 1 traffic when encap-sequence is not configured on priority queue (PQ) 1. Interleaving is allowed for priority level 2 with lower level traffic only when encap-sequence is configured. When classes at priority level 2 or lower not have an encap-sequence assignment, the default mlp_class_id assignment is 0. The following restrictions on interleaving assume only two levels of priority: Interleaving is hierarchical based on priority level. Priority level 1 packets may interleave priority level 2 and nonpriority fragments. Priority level 2 packets should not interleave nonpriority fragments as well as priority level 1 packets. Priority level 2 packets are subject to fragmentation to bound latency for priority level 1 packets. Priority level 1 packets are never fragmented. Configuring Multiclass MLP Support For information on configuring multiclass MLP support on the Cisco series router PRE3/PRE4, see the Multiclass Multilink PPP feature guide at the following URL: Note When configuring multiclass MLP support on the Cisco series router PRE3/PRE4, note the following restrictions: Priority level 1 with no encap-sequence or encap-sequence none results in PQ1 traffic using PPP encapsulation. Priority level 2 with no encap-sequence results in PQ2 traffic using MLP encapsulation and not interleaving with non-pq traffic. The encapsulation sequence range is 0 to15, but cannot be more than the value for negotiated multiclass. The encap-sequence command cannot be defined for a default class. For more information on priority level configuration, see the Multi-Level Priority Queues feature guide at the following URL: 3

4 Configuration Example Configuration Example This section contains the following configuration example: Configuring Using Priority Levels Configuring Using Priority Levels Example 1 shows how to configure multiclass MLP support using priority levels. Example 1 Configuring Multiclass MLP Support Router(config)# policy-map prec1 Router(config-pmap)# class voice Router(config-pmap-c)# priority level 1 Router(config-pmap-c)# police 128 Router(config-pmap-c)# encap-sequence 1 Router(config-pmap-c)# exit Router(config-pmap)# class video Router(config-pmap-c)# priority level 2 Router(config-pmap-c)# police 1000 Router(config-pmap-c)# encap-sequence 2 Router(config-pmap-c)# exit Router(config-pmap)# class game Router(config-pmap-c)# bandwidth 1000 Router(config-pmap-c)# encap-sequence 3 Router(config-pmap-c)# exit Router(config-pmap)# class class-default Verifying Multiclass MLP Support Example 1-2 shows how you can use the show ppp multilink interface multilink 1 command to see the multi-member MLP bundles using XCM reassembly tables. Example 1-2 Multi-member MLP bundles Using XCM Reassembly Tables Router# show ppp multilink interface multilink 1 Multilink1 Bundle name: Remote Endpoint Discriminator: [2] Local Endpoint Discriminator: [2] Bundle up for 00:21:25, total bandwidth 1536, load 1/255 4 receive classes, 4 transmit classes Receive buffer limit bytes per class, frag timeout 1000 ms Bundle is Distributed Receive Class 0: 0x64D received sequence Receive Class 1: 0x0 received sequence 4

5 Additional References Receive Class 2: 0x0 received sequence Receive Class 3: 0x0 received sequence Transmit Class 0: 0x507 sent sequence Transmit Class 1: 0x150 sent sequence Transmit Class 2: 0x0 sent sequence Transmit Class 3: 0x0 sent sequence, 4 receive classes, 4 transmit classes C10K Multilink PPP info Bundle transmit info TX Class Send seq-num 0 0x x x0 3 0x0 Bundle reassembly info RX Class Expected seq-num 0 0x64D 1 0x0 2 0x0 3 0x0 Member links: 1 active, 0 inactive (max 10, min not set) Se1/0/0.1/3:0, since 00:21:27, 5760 weight, 1496 frag size Additional References The following sections provide references related to the multiclass MLP support feature. Related Documents Related Topic No new or modified documents are supported by this feature, and support for existing standards was not modified by this feature. Document Title Standards Standard No new or modified standards are supported by this feature, and support for existing standards was not modified by this feature. Title 5

6 MIBs MIB No new or modified MIBs are supported by this feature, and support for existing MIBs was not modified by this feature. MIBs Link To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator at: RFCs RFC RFC 2686 Title The Multi-Class Extension to Multi-Link PPP 6