Juniper Networks EX2500 User Manual

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Trunking Overview
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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. 
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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.
NOTE: 
Port trunking is also known as link aggregation.