Netgear XCM8810 - 8800 SERIES 10-SLOT CHASSIS SWITCH ユーザーズマニュアル

The last hop router converts the multicast trace query into a unicast traceroute request by 
appending response data (for the last hop router) into the received query packet, and the last 
hop router forwards the request packet to the router that it believes is the proper previous hop 
for the given source and group. Each multicast router adds its response data to the end of the 
request packet, and then forwards the modified unicast request to the previous hop.

The first hop router (the router that determines that packets from the source originate on one 
of its directly connected networks) changes the packet type to response packet and sends 
the completed response to the query generator. If a router along the multicast route is unable 
to determine the forwarding state for a multicast group, that router sends a response back to 
the originator with NO ROUTE forwarding code.

To initiate a multicast trace, use the following command:

mtrace source <src_address> {destination <dest_address>} {group <grp_address>} {from 
<from_address>} {gateway <gw_address>} {timeout <seconds>} {maximum-hops 
<number>} {vr <vrname>}

Multicast Router Information Tool

The multicast router information tool is an XCM8800 command that allows you to request 
information from a specific multicast router. For more information, see the command 
description for the following command:

mrinfo {<router_address>} {from <from_address>} {timeout <seconds>} 

{multiple-response-timeout <multi_resp_timeout>} {vr <vrname>}