Optimizing Port Usage Through Traffic Control and

Optimizing Port Usage Through Traffic Control and Port Trunking

Port Trunking

Table 6-5. General Operating Rules for Port Trunks

Media: All ports on both ends of a trunk group must have the same media type and mode (speed and duplex). The switch blocks any trunked links that do not conform to this rule. (For the Switch 2512 and 2524, HP recommends leaving the port Mode setting at Auto or, in networks using Cat 3 cabling, Auto-10.)

Port Configuration: The default port configuration on the Switch 2512/2524 is Auto, which enables a port to sense speed and negotiate duplex with an Auto-enabled port on another device. HP recommends that you use the Auto setting for all ports you plan to use for trunking. Otherwise, you must manually ensure that the mode setting for each port in a trunk is compatible with the other ports in the trunk.

Recommended Port Mode Setting for LACP

All of the following operate on a per-port basis, regardless of trunk membership:

•Enable/Disable

•Flow control (Flow Ctrl)

•Broadcast limit (Bcast Limit) (Note that the switch automatically adjusts the Bcast Limit setting on individual ports in the trunk to match the trunked port with the highest broadcast limit.) When a broadcast limit is configured on a trunk, removing a port from the trunk sets the broadcast limit for that port to 0 (the default).

LACP is a full-duplex protocol. See “Trunk Group Operation Using LACP” on page 6-24.

Trunk Configuration: All ports in the same trunk group must be the same trunk type (LACP, Trunk, or FEC). All LACP ports in the same trunk group must be either all static LACP or all dynamic LACP.

A trunk appears as a single port labeled Dyn1 (for an LACP dynamic trunk) or Trk1 (for a static trunk of any type: LACP, Trunk, or FEC) on various menu and CLI screens. For a listing of which screens show which trunk types, see “How the Switch Lists Trunk Data” on page 6-28.

For STP or VLAN operation, configuration for all ports in a trunk is done at the trunk level. (You cannot separately configure individual ports within a trunk for STP or VLAN operation.)

Traffic Distribution: All of the switch trunk protocols use the SA/DA (Source Address/Destination Address) method of distributing traffic across the trunked links. See “Outbound Traffic Distribution Across Trunked Links” on page 6-28.

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