Ip Multicast Dvmrp Tunnels Define - 3Com 4007 Command Reference Manual

ip multicast dvmrp
tunnels define
Layer 2
Switching
Modules
Multilayer
Switching
Modules
Defines one end point of a DVMRP tunnel. The other tunnel end point lies
on an IP multicast routing interface on a different system and
subnetwork. One or more unicast routers lie between these tunnel end
points.
Valid Minimum Abbreviation
ip m d t d
Important Considerations
Configure a tunnel only if you need to have IP multicast traffic
forwarded through one or more routers that do not understand IP
multicast protocols and would therefore filter IP multicast packets.
Because IP multicast packets are encapsulated in unicast format at the
tunnel entrance point, the interim routers in the tunnel forward the
packets onward toward the other tunnel exit point.
You can define up to 8 tunnels (tunnel end points) per Multilayer
Switching Module.
You can define multiple tunnel end points on the same local routing
interface in your module, but these tunnels must lead to different
remote routing interfaces.
Think of an IP multicast tunnel end point as being layered on top of a
regular DVMRP routing interface. Therefore, before you can define a
multicast tunnel end point in your module, you must first define at
least one IP virtual LAN (VLAN), enable IP routing, define at least one
IP interface, and enable DVMRP on the interface.
The remote tunnel end point must lie on a different system and
subnetwork.
You must define the tunnel on both end points — that is, on both the
local system and the remote system — even though you specify the
address of the remote interface in the local system (module).
When you define a tunnel with local and remote addresses, the
module automatically assigns the value 1 as both the tunnel metric
and the tunnel TTL threshold, as shown in the IP multicast DVMRP
tunnel summary display. You can change these values through menu
options.
IP multicast interfaces and tunnels have similar characteristics, such as
TTL threshold and metric. The characteristics of a tunnel do not have
to match the characteristics of the interface on which it is configured.
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