Chapter 4

Ports and Trunking

Trunk groups can provide super-bandwidth, multi-link connections between switches or other trunk-capable devices. A trunk group is a group of ports that act together, combining their bandwidth to create a single, larger virtual link. This chapter provides configuration background and examples for trunking multiple ports together.

„Trunking Overview on page 43

„Port Trunking Configuration Example on page 45

„Configurable Trunk Hash Algorithm on page 47

„Link Aggregation Control Protocol on page 47

NOTE: Port trunking is also known as link aggregation.

Trunking Overview

When using port trunk groups between two switches, as shown in Figure 10 on page 45, you can create a virtual link between the switches, operating at up to

120 gigabits per second, depending on how many physical ports are combined. Each EX2500 switch supports up to 12 static trunk groups (portchannels) and up to 24 Link Aggregation Control Protocol (LACP trunk groups, consisting of 1 to 12 ports in each group.

Trunk groups are also useful for connecting a EX2500 switch to third-party devices that support link aggregation, such as routers and switches with EtherChannel technology (not ISL trunking technology) and Sun's Quad Fast Ethernet Adapter. Trunk group technology is compatible with these devices when they are configured manually.

Statistical Load Distribution

Network traffic is distributed statistically between the ports in a trunk group. The switch can use a combination of Layer 2 MAC and Layer 3 IP address information, present in each transmitted frame, to determine load distribution.

Trunking Overview „ 43

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Juniper Networks EX2500 manual Ports and Trunking, Trunking Overview, Statistical Load Distribution