User guide

24 Release Notes for Cisco 2500 Series for Cisco IOS Release 12.0 T
New and Changed Information
Token Ring MPOA is an extension to LAN Emulation (LANE). Using the Next Hop Resolution
Protocol (NHRP), and MPOA server (MPS) on the router, and MPO clients (MPCs) on the ATM
edge devices, a direct virtual channel connection (VCC) between the ingress and egress edge devices
is established. Token Ring MPOA allows Token Ring LANE clients to forward unicast IP packets
between subnets to other Token Ring LANE clients through this shortcut VCC path on the ATM
network.
Web Cache Communications Protocol Version 2 (WCCPv2)
The Web Cache Communications Protocol enables Cisco IOS routing platforms to transparently
redirect content requests (for example, web requests) from clients to a locally connected Cisco
Cache Engine (or Cache Cluster) instead of the intended origin server. When a Cache Engine
receives such a request, it attempts to service it from its own local cache if the requested information
is present. If not, the Cache Engine issues its own request to the originally requested origin server to
get the required information. When the Cache Engine retrieves the requested information, it
forwards it to the requesting client and caches it to fulfill future requests, thus maximizing download
performance and significantly reducing WAN transmission costs.
WCCPv2 provides enhancements to WCCPv1, including:
• Multihome router support enables multiple co-located, WCCP-enabled routers to share a cache
cluster.
• Improved security enables MD5 digital signature authentication (RFC 1321) to be used in Cache
Engine/WCCP router communications.
• Redirection of non-port 80 traffic enables WCCP-enabled routers to transparently redirect traffic
based on any TCP port (for example, FTP and NNTP traffic), in addition to HTTP traffic. Cache
Engine-side support for non-port 80 traffic will be provided in the future.
• Content bypass support—When a Cache Engine rejects a request and sends it back to the
WCCP-enabled router, the router knows not to redirect the request to the Cache Engine again.
• Flexible content distribution within a cache cluster—Various hashing parameters can be used to
determine content distribution within a cache cluster.
X.25 Load Balancing
As the number of users accessing the same host has grown, competition for these application
resources has become a problem. Internet service providers (ISPs) have had to increase the number
of users they could support by increasing the number of X.25 lines to the host.
In order to support a large number of virtual circuits (VCs) to a particular destination, configuration
of more than one serial interface to that destination was needed. When a serial interface is configured
to support X.25, there is a fixed number of VCs available for use.
Using a facility called “hunt-group” (the method for X.25 load balancing), a switch is able to view
a pool of X.25 lines going to the same host as one address and assign VCs on an “idle logical
channel” basis. With this feature, X.25 calls can be load-balanced among all configured outgoing
interfaces to fully use and balance all managed lines. The benefits include, the choice of two
load-balancing distribution methods (rotary or vc-count) and improved performance of serial lines.
New Software Features in Release 12.0(2)T
There are no new features supported by the Cisco 2500 series in Cisco IOS Release 12.0(3)T.