N o t e

Port Trunking

Distributed Trunking

Distributed Trunking

Overview

The IEEE standard 802.3ad requires that all the links in a trunk group originate from the same switch. Distributed Trunking uses a proprietary protocol that allows two or more port trunk links distributed across two switches to create a trunk group. The grouped links appear to the downstream device as if they are from a single device. This allows third party devices to interoperate with the Distributed Trunking switches (DTSs) seamlessly. Distributed trunking also provides node-level Layer 2 resiliency in a Layer 2 network if one of the switches fails.

Distributed trunking switches 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.

The downstream device is a Distributed Trunking Device (DTD). Only servers are supported as DTDs. The DTD (server) 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.

Distributed trunks can be grouped together by configuring two individual dt­ lacp trunks with the same trunk group name in each switch. The DT ports are grouped dynamically after the configuration of distributed trunking. Figure 12-13shows a basic distributed trunking configuration.

Before you configure the switch, it is recommended that you review the “Distributed Trunking Restrictions” on page 12-35for a complete list of operating notes and restrictions.

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