User guide

New and Changed Information
24
Release Notes for Cisco 2500 Series for Cisco IOS Release 12.0 T
78-5563-07 Rev.H0
reports, if any. You then troubleshoot your multicast environment as normal, perhaps using the mtrace
command from the source to the Test Receiver. If the show command displays no error reports, the Test
Receiver is receiving test packets without loss or duplicates from the Test Sender.
PGM Router Assist
The PGM Router Assist feature allows Cisco routers to support the optimal operation of Pragmatic
General Multicast (PGM). The PGM Reliable Transport Protocol itself is implemented on the hosts of
the customer.
PGM is a reliable multicast transport protocol for applications that require ordered, duplicate-free,
multicast data delivery from multiple sources to multiple receivers. PGM guarantees that a receiver in
a multicast group either receives all data packets from transmissions and retransmissions, or can detect
unrecoverable data packet loss. PGM is intended as a solution for multicast applications with basic
reliability requirements. It is network-layer independent; The Cisco implementation of the PGM Router
Assist feature supports PGM over IP.
Service Assurance Agent
The Service Assurance (SA) Agent is both an enhancement to and a new name for the Response Time
Reporter (RTR) feature that was introduced in Cisco IOS Release 11.2. The feature allows you to
monitor network performance by measuring key Service Level Agreement metrics such as response
time, network resources, availability, jitter, connect time, packet loss, and application performance.
With Cisco IOS Release 12.0(5)T, the SA Agent provides new capabilities that enable you to:
• Monitor the Domain Name Server, DHCP Server, and DLSw peer stack and tunnel performance.
Thresholds can be used to trigger additional collection of time delay statistics.
• Monitor network one-way delay variance (jitter) and packet loss.
• Monitor web server response time.
Subnetwork Bandwidth Manager
Resource Reservation Protocol (RSVP) is a signalling mechanism that supports request of specific
levels of service such as reserved bandwidth from the network. RSVP and its service class definitions
are largely independent of the underlying network technologies. This independence requires that a user
define the mapping of RSVP onto subnetwork technologies.
The Subnetwork Bandwidth Manager (SBM) feature answers this requirement for RSVP in relation to
IEEE 802-based networks. SBM specifies a signalling method and protocol for LAN-based admission
control for RSVP flows. SBM allows RSVP-enabled routers and Layer 2 and Layer 3 devices to support
reservation of LAN resources for RSVP-enabled data flows. The SBM signalling method is similar to
that of RSVP itself. SBM protocol entities have the following features:
• Reside in Layer 2 or Layer 3 devices.
• Can manage resources on a segment. A segment is a Layer 2 physical segment shared by one or
more senders, such as a shared Ethernet or Token Ring wire.
• Can become candidates in a dynamic election process that designates one SBM as the segment
manager. The elected candidate is called the Designated Subnetwork Bandwidth Manager (DSBM).
The elected DSBM is responsible for exercising admission control over requests for resource
reservations on a managed segment.