IBM SC30-3681-08 manual Link Integrity Verication Report, Consolidated Link Layer Management Cllm

Using Frame Relay

The PVC status information element contains the following information: the local DLCI number for the particular PVC; the state of the PVC (active or inactive); and whether the PVC is new or an existing PVC that management already knows about.

Note: The number of PVCs supplied at the FR interface is restricted by the network frame size and the amount of individual PVC information elements that can ®t into a full status report. For example, 202 is the maximum number of PVCs for a network with a 1K frame size.

Link Integrity Veri®cation Report

The link integrity veri®cation report, sometimes referred to asheartbeat polling, contains the link integrity veri®cation element. This element is where the exchange of the send and receive sequence numbers takes place. By exchanging sequence numbers, management and the end station can evaluate the integrity of the synchronous link. The send sequence number is the current send sequence number of the message originator. The receiver looks at this number and compares it to the last send sequence number to verify that this number is incrementally correct. The receive sequence number is the last send sequence number that the originator sent out over the interface. It is the receiver's responsibility to place a copy of the send sequence number into the receive sequence number ®eld. This way the originator can ensure that the receiver receives and interprets the frames correctly.

When an end-station fails to participate in this polling process, all remote end-stations with logically attached PVCs are noti®ed through management's full status report mechanism that the PVC is inactive.

Consolidated Link Layer Management (CLLM)

CLLM is an optional FR management function that is not widely supported by the

industry but it has been adopted by some Frame Relay switch manufacturers.

CLLM provides some of the same management information provided by LMI, in

particular, outage noti®cation. CLLM's main use is to provide asynchronous

congestion noti®cation of PVCsto attaching devices. A single CLLM message may

indicate outage or congestion for multiple PVCs. The Frame Relay protocol

supports the following standards for CLLM: ANSI T1.618, ITU-T (CCITT) Q.922

Annex A, and ITU-T (CCITT) X.36 Annex C.

Frame Relay Data Rates

This section introduces data rates for Frame Relay permanent virtual circuits (PVCs).

Committed Information Rate (CIR)

The CIR is the data rate that the network commits to support for the VC under

normal, uncongested conditions. Any VC that is con®gured or is learned is provided

a CIR (by the FR service provider). The CIR is a portion of the total bandwidth of

the physical link of either 0 or between 300 bps and 2 Mbps reserved for the VC.

64 Kbps or a single DS0 channel is most common.

You de®ne the CIR with theadd permanent-virtual-circuit,change

permanent-virtual-circuit,add switched-virtual-circuit, or change

396MRS V3.2 Software User's Guide