IBM SC30-3681-08 manual Connecting to the LES, Control Direct VCC bidirectional point-to-point

Overview of LAN Emulation

vBy default, ELANs use best-effort connections to connect to the BUS. For ELANs where BUS traffic is heavy, better performance can be obtained by using reserved bandwidth connections to the BUS. The characteristics of the Multicast Send VCC between the LE client and the BUS can be controlled with TLVs.

vA TLV can be used to download the ELAN segment number to source route bridges.

In addition to ®ne-tuning the con®guration, TLVs force all clients on the ELAN to operate with consistent parameters. The IBM 2210 supports all ATM Forum-de®ned TLVs along with arbitrary, user-de®ned TLVs.

Connecting to the LES

After obtaining the ATM address of the LES, the LE client initiates a Control Direct VCC to the LES. When this VCC has been established, the LE client sends an LE_JOIN_REQUEST to the LES. The LES responds by adding the LE client to the appropriate point-to-multipoint Control Distribute VCC and returning an LE_JOIN_RESPONSE. By default, the LES partitions proxy and non-proxy clients onto separate Control Distribute VCCs as illustrated in Figure 15; however, you can con®gure the LES to use a single Control Distribute VCC for all LE clients in order to reduce the number of point-to-multipoint VCCs that are required. Partitioning the VCCs is generally useful because it reduces the amount of nuisance traffic that is sent to non-proxy clients. No LE_ARP_REQUESTs are sent to non-proxy LE clients, as described in ªAddress Resolutionº on page 265.

Figure 15. Default Connections Between LE Clients and the LES

The following ATM connections are established between the LE client and the LES:

Control Direct VCC (bidirectional point-to-point)

From LE client to LES

Control Distribute VCC (point-to-multipoint)

From LES to LE client

264MRS V3.2 Software User's Guide