Avaya ERS 8800 series Configuration Manual page 35

IP static route table
The static route table is separate from the system routing table that the router uses to make
forwarding decisions. Use the static route table to directly change static routes. Although the
tables are separate, the system routing table automatically reflects the static routing table
manager entries if the next hop address in the static route is reachable and if the static route
is enabled.
The static route table is indexed by four attributes:
• Destination Network
• Destination Mask
• Next Hop
• ifIndex
The maximum number of entries is 500. You can insert static routes by using the static route
table, and you can delete static routes by using either the static route table or the system routing
table.
Important:
The system routing table stores only active static routes with the best route preference. A
static route is active only if the route is enabled and if the next hop address is reachable (for
example, if a valid ARP entry exists for the next hop).
You can enter multiple routes (for example, multiple default routes) that use different costs and
the lowest cost route that is reachable appears in the routing table. If you enter multiple next
hops for the same route with the same cost, the switch does not replace the existing route. If
you enter the same route with the same cost and a different next hop, the first route is used.
However, if that first route becomes unreachable, the second route (with a different next hop) is
activated with no connectivity loss.
Static routes configured for the management port apply using the natural mask of the network.
Because traffic that originates from the switch refers to these routes before checking the IP
routing table, the switch management traffic can be incorrectly forwarded from the
management port, even though a specific route exists in the routing table.
Black hole static routes
While aggregating or injecting routes to other routers, a router may not use a route to the
aggregated destination, which causes a "black hole." To avoid routing loops, you can configure
a black hole static-route to the destination it is advertising.
A black hole route is a route with invalid next hop, so that the switch drops data packets
destined to this network.
When you specify a route preference, be sure that you configure the preference value
appropriately so that when the black-hole route is used, it gets elected as the best route. Before
Configuration — IPv6 Routing
Routing
November 2010 35