Information Technology Reference
In-Depth Information
After the BSR is selected for the network, it collects a list of candidate RPs. The BSR selects
RP to group mappings, which is called the RP-set, and distributes the selected RPs using
bootstrap messages sent to 224.0.0.13.
DVMRP
DVMRP is described in RFC 1075. It is the primary multicast routing protocol in the Multicast
Backbone (MBONE). The research community uses MBONE.
DVMRP operates in dense mode by having routers send a copy of a multicast packet out all
paths. Routers that receive the multicast packets send prune messages back to their upstream
neighbor router to stop a data stream if no downstream receivers of the multicast group exist
(either receiving routers or hosts on connected segments). DVMRP implements its own unicast
routing protocol, similar to RIP, based on hop counts. DVMRP has been known not to scale
well. Cisco's support of DVMRP is partial; usually DVMRP networks are implemented on
UNIX machines that are running the mrouted process. You usually configure a DVMRP tunnel
to connect to the DVMRP network.
DVMRP Tunnel Configuration
The commands to create a DVMRP tunnel to a DVMRP router are as follows:
interface tunnel 0
ip unnumbered any pim interface
tunnel source address
tunnel destination address
tunnel mode dvmrp
ip pim sparse-dense-mode
References Used
The following resources were used to create this chapter:
Routing TCP/IP,
Volume II, Jeff Doyle, Cisco Press, 2001, (ISBN 1-57870-089-2)
RFC 1112, “Host Extensions for IP Multicasting,” S.E. Deering
RFC 2362 (Experimental), “Protocol Independent Multicast-Sparse Mode (PIM-SM):
Protocol Specification,” D. Estrin, D. Farinacci, A. Helmy, D. Thaler, S. Deering, M.
Handley, V. Jacobson, C. Liu, P. Sharma, L. Wei
RFC 2365, “Administratively Scoped IP Multicast,” D. Meyer
Internet Protocol (IP) Multicast Technology Overview www.cisco.com/warp/public/cc/
pd/iosw/tech/ipmu_ov.htm
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