RE: a token ring question [7:73908]
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
RE: a token ring question [7:73908]
thanks a lot for the reply. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=73936&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
a token ring question [7:73908]
Hi, Can token ring carry multicast traffic? And what's the ip address to mac address mapping if it does? Thanks! Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=73908&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
RE: a token ring question [7:73908]
According to cco cat 3900/5000 can switch multicast on TR. http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr mc_r/mult/1rfmult2.htm#1078651 ip multicast use-functional To enable the mapping of IP multicast addresses to the Token Ring functional address 0xc000.0004., use the ip multicast use-functional command in interface configuration mode. To disable the function, use the no form of this command. ip multicast use-functional no ip multicast use-functional Syntax Description This command has no arguments or keywords. Defaults IP multicast address are mapped to the MAC-layer address 0x... Usage Guidelines This command is accepted only on a Token Ring interface. Neighboring devices on the Token Ring on which this feature is used should also use the same functional address for IP multicast traffic. Because there are a limited number of Token Ring functional addresses, other protocols may be assigned to the Token Ring functional address 0xc000.0004.. Therefore, not every frame sent to the functional address is necessarily an IP multicast frame. Examples The following example configures any IP multicast packets going out Token Ring interface 0 to be mapped to MAC address 0xc000.0004.: interface token 0 ip address 1.1.1.1 255.255.255.0 ip pim dense-mode ip multicast use-functional Martijn -Oorspronkelijk bericht- Van: wj chou [mailto:[EMAIL PROTECTED] Verzonden: dinsdag 12 augustus 2003 7:55 Aan: [EMAIL PROTECTED] Onderwerp: a token ring question [7:73908] Hi, Can token ring carry multicast traffic? And what's the ip address to mac address mapping if it does? Thanks! **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 Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=73909&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
