JUNOS High Availability

Moving Services Away from a Router

High availability requirements are so common these days that pretty much all network hardware manufacturers have developed ways to support software upgrades without interrupting service. One method of doing this is to move traffic away from a router prior to a software upgrade. This way, any device downtime associated with the software upgrade is invisible to the end user. In this section, we describe configuration tweaks appropriate for redirecting traffic in a high availability network.

Interface Configuration

In some situations, simply disabling an interface is the most efficient and desirable way to force traffic onto an alternative path through the network. In Figure 6-1 (shown later), both r3 and r4 support connections to r5. Disabling ge-0/0/0 on r4 by using set disable would effectively force all traffic destined for r5 (and r6) to transit r3:

[edit interfaces ge-0/0/0]
lab@r4# set disable

[edit interfaces ge-0/0/0]
lab@r4# commit
commit complete

[edit interfaces ge-0/0/0]
lab@r4# show
description "r4 ge-0/0/0 to r5 ge-0/0/0";
disable;
unit 0 {
    family inet {
        address 10.0.1.14/30;
    }
    family mpls;
}

[edit interfaces ge-0/0/0]
lab@r4# run show interfaces terse ge-0/0/0
Interface               Admin Link Proto Local                 Remote
ge-0/0/0                down  up
ge-0/0/0.0              up    down inet  10.0.1.14/30
                                   mpls

If you choose to use the set disable command remember to change the interface description accordingly:

[edit interfaces ge-0/0/0]
lab@r4# show description "r4 ge-0/0/0 to r5 ge-0/0/0 ...