Did you copy/paste that right out of a textbook? =) Before I even saw anything indicating that you authored that post, I got about 1/2 way through the paragraph and was thinking to myself "This had to be from Priscilla".....
Mike W. "Priscilla Oppenheimer" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > At 04:42 PM 6/27/02, Lopez, Robert wrote: > >At what OSI layer do IP multicasts lie? Reading through CCO has made me > >more doubtful in my choices. > > IP multicasts are sent to a layer 3 IP multicast address. That address is > converted to a data-link-layer multicast address. The Internet Assigned > Numbers Authority (IANA) owns a block of MAC-layer addresses that are used > for group multicast addresses. The range of addresses for Ethernet is > 0x01:00:5E:00:00:00 through 0x01:00:5E:7F:FF:FF. When a host sends a frame > to an IP group that is identified by a Class D address, the host inserts > the low-order 23 bits of the Class D address into the low-order 23 bits of > the MAC-layer destination address. The top 9 bits of the Class D address > are not used. The top 25 bits of the MAC address are 0x01:00:5E followed by > a zero bit (00000001 00000000 01011110 0 in binary). > > IP multicast gets used for many purposes and those purposes may be at > different layers: > > Sending routing updates (EIGRP, OSPF, RIPv2) - Layer 3 > Establishing routing protocol neighbor relationships (EIGRP, OSPF) - Layer 3 > Sending multimedia streaming audio or video - Layer 7 with some help from > Layer 6 (MPEG or whatever), Layer 5 (RTSP), and Layer 4 (UDP) > Finding services (Service Location Protocol) - Layer 7 > Joining groups (IGMP) - Layer 3 > Determining a dynamic L3 address assignment (IPv6) - Layer 3 > > There's probably lots of others too! > > Layer 2 multicasts are used for IP multicast, but for many other purposes > too, such as BPDU, CDP, VTP, DISL, AppleTalk Name Binding Protocol (NBP) > lookups, etc. > > Priscilla > > > >TIA > > > >Robert > ________________________ > > Priscilla Oppenheimer > http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=47627&t=47591 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
