Specifications

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Release Notes for Cisco IOS Release 12.0 S
78-7130-11 Rev. B0
New and Changed Information
Prior to MBGP, the only way to perform interdomain multicast routing was to use the BGP
infrastructure that was in place for unicast routing. If those routers were not multicast capable, or you
had differing policies where you wanted multicast traffic to flow, you could not support it. See the
following document for further information:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t7/mbgp.htm
Multicast Distributed Switching
Platforms: Cisco 7200 series, Cisco 7500/RSP series, Cisco 12000 series
Prior to multicast distributed switching (MDS), IP multicast traffic was always switched at the Route
Processor (RP) in the Route Switch Processor (RSP)-based platforms. With Cisco IOS Release 11.2 GS
and Release 11.1 CC, IP multicast traffic can be distributed switched on RSP-based platforms with
Versatile Interface Processors (VIPs).
Furthermore, MDS is the only multicast switching method on the Cisco 12000 Gigabit Switch Router
(GSR), starting with Cisco IOS Release 11.2(11)GS.
Switching multicast traffic at the RP has the following disadvantages:
• The load on the RP is increased. This increase affects important route updates and calculations (for
BGP, among others) and can stall the router if the multicast load is significant.
• The net multicast performance is limited to what a single RP can switch.
MDS solves these problems by performing distributed switching of multicast packets received at the
line cards (VIPs in the case of an RSP, and line cards in the case of a GSR). The line card is the interface
card that houses the VIPs (in the case of RSP) and the GSR line card (in the case of a GSR). MDS is
accomplished using a forwarding data structure called a Multicast Forwarding Information Base
(MFIB), which is a subset of the routing table. A copy of MFIB runs on each line card and is always
kept up to date with the RP MFIB table.
In the case of RSP, packets received on non-VIP interface processors are switched by the RP.
MDS can work in conjunction with Cisco Express Forwarding (CEF), unicast distributed fast switching
(DFS), or flow switching. See the following document for further information:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios111/cc111/mds.htm
Multicast Routing Monitor
Platforms: Cisco 7200 series, Cisco 7500/RSP series, Cisco 12000 series
The Multicast Routing Monitor (MRM) feature is a management diagnostic tool that provides network
fault detection and isolation in a large multicast routing infrastructure. It is designed to notify a network
administrator of multicast routing problems in near real time.
MRM has three components that play different roles: the Manager, the Test Sender, and the Test
Receiver. The Manager can reside on the same device as the Test Sender or Test Receiver. You can test
a multicast environment using test packets (perhaps before an upcoming multicast event), or you can
monitor existing IP multicast traffic.
You create a test based on various test parameters, name the test, and start the test. The test runs in the
background and the command prompt returns. If the Test Receiver detects an error (such as packet loss
or duplicate packets), it sends an error report to the router configured as the Manager. The Manager
immediately displays the error report. Also, by issuing a certain show command, you can see the error