TNETX4080GGP datasheet(44/64 Pages) TI1

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TNETX4080

ThunderSWITCH II™ 8-PORT 10-/100-MBIT/S ETHERNET™ SWITCH

SPWS050A – AUGUST 1998 – REVISED NOVEMBER 1998

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

port trunking example

This example shows how to set up the TNETX4080 to support two port trunks. The first trunk group consists

of ports 1, 3, 5, and 7 (see Table 14); the second trunk group consists of ports 0, 2, and 6 (see Table 15).

Table 14. Trunk Group 0 Port Membership (Trunk0Ports Register)

PORT

Table 15. Trunk Group 1 Port Membership (Trunk1Ports Register)

PORT

The TrunkMapx registers are used to control the distribution of traffic across the ports within a trunk group. In

this example, the traffic for trunk group 0 has been equally distributed 25% (this assumes that bits 3–1 of the

MAC addresses are random enough to give an even distribution) for each of the four ports in the trunk. For any

given source and destination address pair, the traffic always uses the same port within the trunk. This ensures

that packets do not get disordered on the trunk ports. Note that since port 4 is not a member of any port trunk

group, all the entries for this port have been set to 1. In fact, funtionally, this can be thought of as a single-port

trunk (see Table 16).

Table 16. TrunkMapx Register Settings (for Traffic Distribution on Trunk Groups 0 and 1)

MAP

TRUNK PORT

INDEX

TNETX4080GGP Datasheet(PDF) 44 Page - Texas Instruments