Frame relay multipoint and point to point.

Can any one confirm this is correct please.

by default the physical interface is multipoint, and the sub interface is point to point.

And the difference is that, split horision is disabled on multipoint but enabled on point to point.

Or what else does the command

#int f1/0.1 point-to-point / multipoint achieve?

Because as far as I can see you can still set up and interface with either the, interface delci command, or the framerelay map method (point to point / multipoint). which ever you chose? ( so the command ccan still be seen but it does stop you running it!, but still is this the only thing that setting the link type affects?)

Cheers

Aaron

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Comments

Forsaken_GA

split horizon isn't disabled for all protocols on multi-point by default, I think IPX and AppleTalk both still get pissy about it in multipoint. So if you configure subinterfaces, traffic which comes in one interface can still go back out that interface because the router considers the subinterfaces to be unique

multipoint subinterfaces are really only useful if you've got a multipoint network and you're migrating to a point to point structure. Since you can't really take it all down at once to migrate without taking the entire network offline, you define the multipoint subinterfaces to keep your multipoint network intact, but then you can convert individual links to point-to-point and not violate any split horizon rules

DevilWAH

but does the actual command do? it seems a bit redundent. apart from determining what frame relay commands will run. are there actualy any changes to the interface the pointt to point or multi point command achives?

Forsaken_GA

If you need a single interface to support both point-to-point connections and point-to-multipoint connections, you need your subinterfaces to be able to function as either. If the multipoint designation for the subinterfaces didn't exist, you'd be forced to choose instead of being able to do both.

DevilWAH

coming back to the multipoint and point to point interfaces.

I am correct in thinking that point to point will forward broadcast by default to form neighbours? and with multipoint you have to add it to the framer relay map? arnt I ?

Forsaken_GA

DevilWAH wrote: »

coming back to the multipoint and point to point interfaces.

I am correct in thinking that point to point will forward broadcast by default to form neighbours? and with multipoint you have to add it to the framer relay map? arnt I ?

I'm assuming you actually mean multicast

Yeah, point to point subs will forward broadcast/multicast traffic without any additional manipulation, the other types you have to use frame relay maps to tell the router to convert broadcasts to unicasts

mella060

DevilWAH wrote: »

coming back to the multipoint and point to point interfaces.

I am correct in thinking that point to point will forward broadcast by default to form neighbours? and with multipoint you have to add it to the framer relay map? arnt I ?

Well yes, multipoint subinterfaces act like an NBMA physical interface which means that they will not send broadcasts/multicasts by default.

Point to point subinterfaces emulate a normal point to point leased line link, so they will send the broadcasts just like they would on a normal point to point serial link.