Route Redistribution - Avaya P334T-ML User Manual

Chapter 1 Overview
When the interface is enabled, the static route becomes active again.
Static routes can only be configured for remote destinations, i.e. destinations that
are reachable via another router as a next hop. The next hop router must belong to
one of the directly attached networks for which P334T-ML has an IP interface.
"Local" static routes, such as those that have no next hop, are not allowed.
Two kinds of static routes can be configured, High Preference static routes which
are preferred to routes learned from any routing protocol and Low Preference static
routes which are used temporarily until the route is learned from a routing protocol.
By default, a static route has Low Preference.
Static routes can be advertised by routing protocols (i.e. RIP, OSPF) as described
under Route redistribution.
Static routes also support load-balancing similar to OSPF. A static route can be
configured with multiple next hops so that traffic is split between these next hops.
This can be used for example to load-balance traffic between several firewalls which
serve as the default gateway.

Route Redistribution

Route redistribution is the interaction of multiple routing protocols. OSPF and RIP
can be operated concurrently in P334T-ML. In this case, P334T-ML can be
configured to redistribute routes learned from one protocol into the domain of the
other routing protocol. Similarly, gor routes may be redistributed to RIP and to
OSPF. Route redistribution should not be configured carelessly, as it involves metric
changes and might cause routing loops in the presence of other routes with
incompatible schemes for route redistribution and route preferences.
The P334T-ML scheme for metric translation in route redistribution is as follows:
• Static to RIP metric configurable (default 1)
• OSPF internal metric N to RIP metric 1
• OSPF external type 1 metric N to RIP metric 1
• OSPF external type 2 metric N to RIP metric N+1
• Static to OSPF external type 2, metric configurable (default 1)
• RIP metric N to OSPF external type 2, metric N
• Direct to OSPF external type 2, metric 1.
By default, the P334T-ML does not redistribute routes between OSPF and RIP.
Redistribution from one protocol to the other can be configured. Static routes are, by
default, redistributed to RIP and OSPF. P334T-ML allows the user to globally
disable redistribution of static routes to RIP, and separately to globally disable
redistribution of static routes to OSPF. In addition, P334T-ML lets the user
configure, on a per static route basis, whether the route is to be redistributed to RIP
and OSPF, and what metric (in the range of 1-15). The default state is to enable the
route to be redistributed at metric 1. When static routes are redistributed to OSPF,
they are always redistributed as external type 2.
12 P334T-ML User's Guide