Frame relay sub-interface

[hanwucisco]

When you configure a sub-interface into Frame-relay. There are two options, one is point-to-point, the other is “multipoint”. I am just wondering what exactly is the “multipoint” used for? Or in what case is it used?

router(config)#interface s0/0.1

multipoint          Treat as a multipoint link

point-to-point     Treat as a point-to-point link

Thanks,

[#2]

The basic answer is a point-to-point sub interface will be treated as a point-to-point connection and will require a different subnet for each leg of the frame circuits. A multi point interface will be on the same subnet as all of your frame legs (circuits). There are a number of caveats to each; here is a good doc;

http://www.ciscopress.com/articles/article.asp?p=170741&seqNum=6