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Configuring Redundant Trunk Links for Faster Recovery (CLI Procedure)

You can manage network convergence by configuring both a primary link and a secondary link on an EX Series switch; this is called a redundant trunk group (RTG). If the primary link in a redundant trunk group fails, it passes its known MAC address locations to the secondary link, which automatically takes over. You can configure a maximum of 16 redundant trunk groups on most standalone switches or on Virtual Chassis. The EX8200 switch and EX8200 Virtual Chassis, however, support up to 254 redundant trunk groups.

Generally, you configure a redundant trunk group by configuring one primary link (and its interface) and one unspecified link (and its interface) to serve as the secondary link. A second type of redundant trunk group, not shown in the procedure in this topic, consists of two unspecified links (and their interfaces); in this case, neither of the links is primary. In this second case, the software selects an active link by comparing the port numbers of the two links and activating the link with the higher port number. The procedure given here describes configuring a primary/unspecified configuration for a redundant trunk group because that configuration gives you more control and is more commonly used.

Rapid Spanning Tree Protocol (RSTP) is enabled by default on EX Series switches to create a loop-free topology, but an interface is not allowed to be in both a redundant trunk group and in a spanning-tree protocol topology at the same time.

A primary link takes over whenever it is able. You can, however, alter the number of seconds that the primary link waits before reestablishing control by configuring the primary link’s preempt cutover timer.

Before you configure the redundant trunk group on the switch, be sure you have:

  • Disabled RSTP on all switches that will be linked to your redundant trunk group.
  • Configured at least two interfaces with their port mode set to trunk; be sure that these two interfaces are not part of any existing RTG. See Configuring Gigabit Ethernet Interfaces (CLI Procedure) .

To configure a redundant trunk group on a switch:

  1. Turn off RSTP:
    [edit]
    user@switch# set protocols rstp disable
  2. Name the redundant trunk group while configuring one primary and one unspecified trunk interface:
    [edit ethernet-switching-options]
    user@switch# set redundant-trunk-group group name interface interface-name primary
    user@switch# set redundant-trunk-group group name interface interface-name
  3. (Optional) Change the length of time (from the default of 1 second) that a re-enabled primary link waits to take over from an active secondary link:
    [edit ethernet-switching-options]
    set redundant-trunk-group group name preempt-cutover-timer seconds
 

Related Documentation

 

Modified: 2016-01-26

Supported Platforms

 

Related Documentation

 

Modified: 2016-01-26

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