Routing Packets To A Gre Tunnel - Avaya G450 Manual

A GRE tunnel is set up as an IP interface, which allows you to use the GRE tunnel as a routing
destination. A GRE tunnel can transport multicast packets, which allows it to work with routing
protocols such as RIP and OSPF.
To set up a GRE tunnel, you must create the interface and assign it an IP address, a tunnel
source address, and a tunnel destination address. GRE tunnels can be configured as next hops
on static routes and policy-based routing next hop lists. Packets can also be routed to GRE
tunnels dynamically.
Note:
There may be cases in which the GRE tunnel is not used for routing. In such
Note:
cases, it may not be necessary to assign an IP address to the tunnel.
The main application for GRE tunneling is to allow packets that use protocols not supported on
the Internet, or packets that use private IP addresses that cannot be routed on the Internet, to
travel across the Internet. The following are examples of situations in which this can be useful:
Providing multiprotocol local networks over a single-protocol backbone
●
Providing workarounds for networks containing protocols that have limited hop counts,
●
such as AppleTalk
Connecting discontinuous subnetworks
●
Enabling virtual private networks (VPNs) over a WAN
●
You can also configure a GRE tunnel to serve as a backup interface. For information on
configuring backup interfaces, see
For an example of a GRE tunneling application, see
page 464.

Routing packets to a GRE tunnel

Packets can be routed to a GRE tunnel in the following ways:
The Tunnel interface is configured as the next hop in a static route. See
●
routing table
The packet is routed to the Tunnel interface dynamically by a routing protocol (RIP or
●
OSPF)
The packet is routed to the Tunnel interface via policy-based routing. See
●
policy-based routing
Backup interfaces
on page 451.
on page 619.
Configuring GRE tunneling
on page 268.
GRE tunnel application example
Issue 1 January 2008
on
Configuring the
Configuring
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