Alternative Routes

Table 1. Alternative routes product support

Feature

Product

Release introduced

Alternative routes for IPv4

5320 Series

Fabric Engine 8.6

5420 Series

VOSS 8.4

5520 Series

VOSS 8.2.5

5720 Series

Fabric Engine 8.7

7520 Series

Fabric Engine 8.10

7720 Series

Fabric Engine 8.10

VSP 4450 Series

VSP 4000 4.0

VSP 4900 Series

VOSS 8.1

VSP 7200 Series

VOSS 4.2.1

VSP 7400 Series

VOSS 8.0

VSP 8200 Series

VSP 8200 4.0

VSP 8400 Series

VOSS 4.2

VSP 8600 Series

VSP 8600 4.5

XA1400 Series

VOSS 8.0.50

Alternative routes for IPv6

5320 Series

Fabric Engine 8.6

5420 Series

VOSS 8.4

5520 Series

VOSS 8.2.5

5720 Series

Fabric Engine 8.7

7520 Series

Fabric Engine 8.10

7720 Series

Fabric Engine 8.10

VSP 4450 Series

VOSS 5.1

VSP 4900 Series

VOSS 8.1

VSP 7200 Series

VOSS 5.1

VSP 7400 Series

VOSS 8.0

VSP 8200 Series

VOSS 5.1

VSP 8400 Series

VOSS 5.1

VSP 8600 Series

VSP 8600 6.2

XA1400 Series

Not Supported

To avoid traffic interruption, you can globally enable the alternative routes feature so the router can use the next-best route, also known as an alternative route, if the best route becomes unavailable.

Routers learn routes to a destination through routing protocols. Routers maintain a routing table of the learned alternative routes sorted in order by route preference, route costs, and route sources. The first route on the list is the best route and the route that the router prefers to use.

The alternative route concept also applies between routing protocols. For example, if an OSPFv3 route becomes unavailable and an alternative RIPng route is available, the system activates the RIPng route without waiting for the update interval to expire.