Built-In Fault Tolerance; Before Configuring Static Trunks; Trunk Group Configuration Rules - Juniper EX2500 Configuration Manual

EX2500 Ethernet Switch Configuration Guide

Built-In Fault Tolerance

Before Configuring Static Trunks

Trunk Group Configuration Rules

44
Trunking Overview
Each packet's particular MAC or IP address information results in selecting one line
in the trunk group for data transmission. The more data streams are feeding the
trunk lines, the more evenly traffic is distributed.
Since each trunk group is made up of multiple physical links, the trunk group is
inherently fault tolerant. As long as one connection between the switches is
available, the trunk remains active.
Statistical load balancing is maintained whenever a port in a trunk group is lost or
returned to service.
When you create and enable a static trunk, the trunk members (switch ports) take
on certain settings necessary for correct operation of the trunking feature.
Before you configure your trunk, you must consider these settings, along with
specific configuration rules, as follows:
1. Read the configuration rules provided in the section, "Trunk Group
Configuration Rules" on page 44.
2. Determine which switch ports (up to 12) are to become trunk members (the
specific ports making up the trunk).
Ensure that the chosen switch ports are set to enabled . Trunk member ports
must have the same VLAN and Spanning Tree configuration.
3. Consider how the existing Spanning Tree will react to the new trunk
configuration. See "Spanning Tree Protocol" on page 31 for Spanning Tree
Group configuration guidelines.
4. Consider how existing VLANs will be affected by the addition of a trunk.
The trunking feature operates according to specific configuration rules. When
creating trunks, consider the following rules that determine how a trunk group
reacts in any network topology:
All trunks must originate from one device, and lead to one destination device.
Any physical switch port can belong to only one trunk group.
Trunking from third-party devices must comply with EtherChannel technology.
When ports become members of a trunk, configuration parameters (except
ACL and QoS) are applied per trunk. When a trunk group is formed, these
parameters are configured for the trunk ID, which overrides the port-level
parameters.
All trunk member ports must be assigned to the same VLAN configuration
before the trunk can be enabled.