wj chou wrote: > > Hi, > Can token ring carry multicast traffic?
Yes. > And what's the ip > address to mac address mapping if it does? > Thanks! That is a loaded question, seeped in history. Although IEEE 802.5 does have the same group/individual bit as Ethernet (the first bit transmitted) and theoretically should support a simple method of multicast addressing and translation from a L3 multicast to L2 multicast address, alas, it does not. Legacy problems never really disappear. Token Ring was implemented by IBM and others, mostly based on IBM's Token Ring Architectural Reference Manual, and not based entirely on IEEE specifications. One problem was that those early Token Ring implementations didn't support true multicast addresses. Instead, they supported functional addresses, of which there are only 31. Although this problem was recognized years ago, it still haunts us. RFC 1469 specifies how to support IP multicast on Token Ring by using the functional address C0-00-00-04-00-00 (in non-canonical format). All IP multicast addresses are mapped to this address, (as are a few other addresses). And that's how it is usually done, despite the fact that Token Ring chipsets could support a better method these days. Priscilla Oppenheimer > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=73926&t=73908 -------------------------------------------------- **Please support GroupStudy by purchasing from the GroupStudy Store: http://shop.groupstudy.com FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
