6.3.1 Protocol Overview

## 6.3 Multicast Protocol Statements

### 6.3.1 Protocol Overview

### 6.3.2 Intra-Domain Routing Protocols

Interior protocols are used to exchange reachability information within an autonomous system (AS). They are referred to as a class by the acronym igp. There are two interior protocols currently supported by this version of GateD:

DVMRP
  Distance Vector Multicast Routing Protocol (DVMRP) is the original IP Multicast routing protocol. It was designed to run over both multicast capable lans (like Ethernet) as well as through non-multicast capable routers. In this case, the IP Multicast packets are "tunneled" through the routers as unicast packets. This replicates the packets and has an effect on performance, but has provided an intermediate solution for IP Multicast routing on the Internet while router vendors decide to support native IP Multicast routing.

PIM
  PIM was designed to take advantage of two existing multicast routing protocols, DVMRP and CBT. It exibits the behavior of a protcol in a region of dense group membership flooding multicast packets using Reverse Path Multicasting, while also taking advantage of the work done for sparse group membership in Core Based Trees. Hence, the protocol has two modes: dense mode (PIM-DM), and sparse mode (PIM-SM). Currently, only dense mode is implemented in Gated

PIM-DM
  Intermediate System to Intermediate System (ISIS) is a link state interior gateway protocol (IGP) originally developed for routing ISO/CLNP (International Organization for Standardization/Connectionless Network Protocol) packets. The version distributed with GateD can route IP packets as well.
PIM-SM

### 6.3.3 Inter-Domain Routing Protocol

M-BGP

### 6.3.4 Other Routing Protocols

### 6.3.5 Other Support

IGMP
Internet Group Management Protocol (IGMP) was primarily designed for hosts on multi-access networks to inform locally attached routers of their group membership information. This is performed by hosts multicasting IGMP Host Membership Reports. Multicast routers listen for these messages and can then exchange group membership information with other multicast routers. This allows distribution trees to be formed to deliver multicast datagrams.
MBR

Last updated April 26, 1997 (11:59AM)

gated@gated.merit.edu