User guide

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Release Notes for Cisco 2500 Series for Cisco IOS Release 12.0 T
78-5563-07 Rev.H0
New and Changed Information
IOS STP Enhancements
IOS Spanning Tree Protocol enhancements broaden the original IOS STP implementation with
increased port identification capability, improved path cost determination, and support for a new VLAN
bridge spanning-tree protocol.
Layer Two Tunneling Protocol (L2TP)
Layer Two Tunneling Protocol (L2TP) is an emerging Internet Engineering Task Force (IETF) standard
that combines the best features of two existing tunneling protocols: Cisco's Layer Two Forwarding
(L2F) and Microsoft's Point-to-Point Tunneling Protocol (PPTP). L2TP is an extension to the
Point-to-Point Protocol (PPP), which is an important component for Access Virtual Private Networks
(VPNs). Access VPNs allow mobile users to connect to their corporate intranets or extranets, thus
improving flexibility and reducing costs.
Traditional dial-up networking services only supported registered IP address, which limited the types
of applications that could be implemented over Virtual Private Networks (VPNs). L2TP supports
multiple protocols and unregistered and privately administered IP addresses over the Internet. This
allows the existing access infrastructure, such as the Internet, modems, access servers, and ISDN
terminal adaptors (TAs), to be used.
L2TP can be initiated wherever PPTP or L2F is currently deployed and can be operated as a client
initiated tunnel, such as PPTP, or a network access server (NAS) initiated tunnel, such as L2F.
PPP Over Frame Relay
The PPP over Frame Relay feature allows a router to establish end-to-end Point-to-Point Protocol (PPP)
sessions over Frame Relay. IP datagrams are transported over the PPP link using RFC 1973 compliant
Frame Relay framing. This feature is useful for remote users running PPP to access their Frame Relay
corporate networks.
PPP over Frame Relay provides the following benefits:
• Allows end-to-end PPP sessions over Frame Relay.
• Supports the 90i IDSL Channel Unit that supports both Frame Relay and Point-to-Point Protocol
(PPP) on an ISDN DSL.
Data Compression Advanced Interface Module
This document describes how to configure, verify, and troubleshoot the Data Compression features of
the Advanced Interface Module (AIM) on Cisco 2600 Series Routers. The Data Compression AIM
provides hardware-based compression and decompression of packet data transmitted and received on
the serial network interfaces of Cisco 2600 Series Routers without occupying the Port Module Slot, that
might otherwise be used for additional customer network ports. Supported are the industry standard
LZS and MPPC compression algorithms. The Data Compression AIM requires Cisco IOS Release
12.0(1)T, or later 12.0 T releases.
ATM PVC Trap Support
The ATM PVC Trap Support feature provides Simple Network Management Protocol (SNMP)
notification for permanent virtual circuit (PVC) failures, and it provides SNMP access to PVC status
tables.