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any other networking device that supports trunking to interoperate with the distributed trunking

switches (DTSs) seamlessly. Distributed trunking provides device-level redundancy in addition to

link failure protection.

DTSs are connected by a special interface called the InterSwitch-Connect (ISC) port. This interface

exchanges information so that the DTSs appear as a single switch to a downstream device, as

mentioned above. Each distributed trunk (DT) switch in a DT pair must be configured with a separate

ISC link and peer-keepalive link. The peer-keepalive link is used to transmit keepalive messages

when the ISC link is down to determine if the failure is a link-level failure or the complete failure

of the remote peer.

The downstream device is a distributed trunking device (DTD.) The DTD forms a trunk with the DTSs.

The connecting links are DT links and the ports are DT ports. A distributed trunk can span a maximum

of two switches.

NOTE: All DT linked switches must be running the same software version.

You can group together distributed trunks by configuring two individual dt-lacp/dt-trunk trunks with

the same trunk group name in each switch. The DT ports are grouped dynamically after the

configuration of distributed trunking.

NOTE: Before you configure the switch, HP recommends that you review the “Distributed trunking

restrictions” (page 168) for a complete list of operating notes and restrictions.

In Figure 64 (page 160), three different distributed trunks with three different servers have one

common ISC link. Each trunk spans only two DTSs, which are connected at the ISC ports so they

can exchange information that allows them to appear as one device to the server.

Figure 64 Example of distributed trunking with three different distributed trunks with three servers

An example of distributed trunking switch-to-switch in a square topology is shown in Figure 65

(page 161).

160 Port Trunking