From: Jay Hennigan (jay@west.net)
Date: Sun May 25 2003 - 23:35:04 GMT-3
On Mon, 26 May 2003, Tom Young wrote:
> hi, group
>
> Look the config below, I don't want to use inver-arp on
> the interface, but on the p2p interface, It seems I
> haven't choose, only the inver-arp that I have to use.
> Why?
>
>
> r4(config-subif)#frame map ip 133.3.13.3 403 b
> FRAME-RELAY INTERFACE-DLCI command should be used on
> point-to-point interfaces
On a point-to-point interface, packets leaving have only one possible
destination, the other point. You don't need inverse-arp. Use the
frame-relay interface-dlci command to map the DLCI to the subinterface
and assign the local IP address to it. Do the same on the other end.
For example:
r4(config)# interface serial0/1
r4(config-if)# encapsulation frame-relay ietf
r4(config-if)# interface serial 0/1.403 point-to-point
r4(config-subif)# ip address 133.3.13.4 255.255.255.0 [note 1]
r4(config-subif)# frame-relay interface-dlci 403
If you have traffic with a next-hop of 133.3.13.3 it will leave that
subinterface, and the only thing on the other side of DLCI 403 has to
be 133.3.13.3.
If you had a multipoint frame interface, then you would have to map
IP addresses to DLCIs so that the router could determine the correct
layer 2 DLCI on which to send IP traffic based on the map. For example
you might have a multipoint interface with DLCIs 402, 403 and 405, each
of which goes to a different router with a different next-hop IP address.
In this case you would need to map each next-hop IP to its DLCI in
order to ensure that IP traffic leaves on the appropriate PVC.
For example:
r4(config)# interface serial0/1
r4(config-if)# encapsulation frame-relay ietf
r4(config-if)# interface serial0/1.400 multipoint
r4(config-subif)# ip address 133.3.13.4 255.255.255.0
r4(config-subif)# frame-relay map ip 133.3.13.2 402 broadcast
r4(config-subif)# frame-relay map ip 133.3.13.3 403 broadcast
r4(config-subif)# frame-relay map ip 133.3.13.5 405 broadcast
[note 1] In the real world, a /30 mask for point-to-point links makes
more sense, but won't work with your example having .3 as the last octet.
Why this won't work is left as an exercise for the reader. :-)
-- Jay Hennigan - CCIE #7880 - Network Administration - jay@west.net NetLojix Communications, Inc. - http://www.netlojix.com/ WestNet: Connecting you to the planet. 805 884-6323
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