HP-UX Routing Services Administrator's Guide HP-UX 11i v2, HP-UX 11i v3 (B2355-91153, November 2011)

1 Overview
A router is a device that has multiple network interfaces and that transfers Internet Protocol (IP)
packets from one network or subnet to another within an internetwork. In many IP-related documents,
this device is also referred to as a gateway. The term router is used in this manual. The router stores
all the routing information in the form of a routing table. Routing tables contain the routes to reach
a particular network, and also identify the router to which the datagram packet can be passed for
this purpose. The routing tables must contain the latest routing information. Routing protocols
perform the task of updating the routing tables with the latest routing information.
The primary function of a routing protocol is to exchange routing information with other routers.
Routing daemons perform the task of exchanging routing information with other routers. The routing
daemons supported on the HP-UX 11i v2 and HP-UX 11i v3 operating systems are mrouted,
gated 3.5.9 and ramD.
A detailed description of the routing daemons, their configuration and troubleshooting information
is provided in this manual.
This chapter contains information about the following topics:
• “The mrouted Routing Daemon” (page 8)
• “The gated Routing Daemon” (page 10)
• “The ramD Routing Daemon” (page 13)
The mrouted Routing Daemon
mrouted (pronounced “M route D”) is a routing daemon that forwards IP multicast datagrams,
within an autonomous network, through routers that support IP multicast addressing. mrouted
implements the Distance-Vector Multicast Routing Protocol (DVMRP). The ultimate destination of
multicast datagrams are host systems that are members of one or more multicast groups.
Multicasting enables a client to establish one-to-many and many-to-many communication with other
hosts and is used extensively in networking applications such as audio and video teleconferencing,
where multiple hosts need to communicate with each other simultaneously.
NOTE: You cannot use the HP System Management Homepage (HP SMH) to configure mrouted.
mrouted routes multicast datagram packets only on certain network interfaces, such as EISA
Ethernet (lan2) and EISA FDDI (from a provider other than HP), and the interface types vary
depending on the system platform.
When you install the HP-UX 11i v2 or the HP-UX 11i v3 operating system, mrouted is automatically
installed on your system.
For more information on mrouted, type man 1m mrouted at the HP-UX prompt.
Multicasting Overview
This section describes the multicast routing protocol implemented in mrouted, and the multicast
addresses and groups.
DVMRP Protocol
mrouted implements the Distance-Vector Multicast Routing Protocol (DVMRP). You can use DVMRP,
an Interior Gateway Protocol (IGP), to route multicast datagrams within an autonomous network.
The primary purpose of DVMRP is to maintain the shortest return paths to the source of the multicast
datagrams. You can achieve this by using topological knowledge of the network to implement a
multicast forwarding algorithm called Truncated Reverse Path Broadcasting (TRPB).
8 Overview