Enterasys Networks FN 100 manual Using FN100 Trunking

Chapter 4

Using FN100 Trunking

The Trunking Table window; enabling and disabling trunking

Trunking, an extension of the 802.1D Spanning Tree protocol, allows you to increase aggregate bandwidth when two or more switches are connected. A single 10/100BASE-T connection between switches yields 10 or 100 Mbps of bandwidth, depending on the speed of the ports used for the connection. A trunk group is created when two or more ports on the same switch (for which trunking protocol is enabled) are physically connected to the same remote switch. By creating a trunk group, each additional connection results in another 10 or 100 Mbps of bandwidth, since the group of ports effectively acts as a single connection. The trunking protocol modifies Spanning Tree to allow the redundant links which form a trunk group. Trunking can be enabled or disabled for a port using the Trunking Table window (Figure 4-1). Trunking can be enabled for use on up to eight ports per switch, allowing you to configure up to four trunk groups potentially yielding 80 or 800 Mbps of bandwidth, depending on the speed of the interfaces.

NOTE

Although you can enable trunking for more than eight ports on an FN100 (if more than eight ports exist on your device), the trunking protocol prohibits the use of trunking on more than eight ports at a time. If you enable trunking and establish a valid link for a ninth port, the extra port will be in “hot standby” mode. If connections are broken for any of the original eight trunk ports, the hot standby port will then participate in trunking, provided that it has a valid link to a remote switch which is participating in a trunk group.

You can add ports of different interface speeds to the same trunk groups; however, doing so

!will cause the higher speed ports to assume the same bandwidth as the lower speed ports,

so you effectively lose any transmission speed benefits for the faster port.CAUTION

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