Cisco Cisco IOS Software Release 12.2(1)DX

Platforms: Cisco 7200 and Cisco 7400 series routers

The PPPoE Session Limit feature enables you to limit the number of PPPoE sessions that can be created 
on a router or on an ATM PVC, PVC range, or VC class, or Ethernet subinterface.

Before the introduction of this feature, there was no way to limit the number of PPPoE sessions that 
could be created on a router. Not having a limit was potentially a problem because it was possible that 
the router could create so many PPPoE sessions that it would run out of memory. 

To prevent the router from using too much memory for virtual access, the PPPoE Session Limit feature 
introduces a new command and a modification to an existing command that enable you to specify the 
maximum number of PPPoE sessions that can be created. The new pppoe limit max-sessions command 
limits the number of PPPoE sessions that can be created on the router. The modified pppoe max-sessions 
command limits the number of PPPoE sessions that can be created on an ATM PVC, PVC range, VC 
class, or Ethernet subinterface.

Platform: Cisco 7200 VXR using a Network Services Engine (NSE)

The Modular Quality of Service Command-Line Interface (Modular QoS CLI) and many of the 
associated class-based QoS features are now available on PXF.

The following class-based QoS features are being introduced for PXF:

Traffic Policing—The police command in policy map class configuration mode.

Class-Based Weighted Fair Queueing (CBWFQ)—The bandwidth and fair-queue commands in 
policy map class configuration mode.

Low Latency Queueing (LLQ)—The priority command used in policy map class configuration 
mode.

Class-Based Weighted Random Early Detection (CBWRED) and Differentiated Services- 
Compliant Weighted Random Early Detection (DiffServ-Compliant WRED)—The random-detect 
command used simultaneously with the bandwidth command in policy map class configuration 
mode.

Flow-Based Weighted Random Early Detection—The random-detect command used 
simultaneously with the bandwidth command in policy map class configuration mode.

Class-Based Marking—The set command used in policy map class configuration mode. 
Class-Based Marking support is limited to 32 traffic classes per traffic policy, and QoS group 
marking (set qos-group) is not supported.

The Committed Access Rate (CAR) feature configured to use an access list with rate-limiting policies 
(the access-list rate-limit command in interface configuration mode) is also now available on PXF. If 
you wish to rate-limit traffic without using an ACL, use the Modular QoS CLI to configure the Traffic 
Policing feature.

Because of the addition of the Modular QoS CLI, traditional WRED (the random-detect command in 
interface configuration mode) and Fair Queueing (the fair-queue command in interface configuration 
mode) are no longer configurable. If you would like to configure WRED or Fair Queueing, you can use 
the Modular QoS CLI to configure Class-Based WRED or Class-Based Weighted Fair Queueing on a 
per-class rather than a per-interface basis.