HP 6125G HP 6125G & 6125G/XG Blade Switches IP Multicast Configuration - Page 73

Introduction to multicast traceroute packets, Process of multicast traceroute, Configuration task

Page 73 highlights

• First-hop router-The router that directly connects to the multicast source is called the "first-hop router". • Querier-The router that sends multicast traceroute requests is called the "querier". Introduction to multicast traceroute packets A multicast traceroute packet is a special IGMP packet that is different from common IGMP packets in that its IGMP Type field is set to 0x1F or 0x1E and its destination IP address is a unicast address. The following types of multicast traceroute packets are available: • Query, with the IGMP Type field set to 0x1F, • Request, with the IGMP Type field set to 0x1F, and • Response, with the IGMP Type field set to 0x1E. Process of multicast traceroute 1. The querier sends a query to the last-hop router. 2. After receiving the query, the last-hop router turns the query packet into a request packet by adding a response data block (which contains its interface addresses and packet statistics) to the end of the packet. It then forwards the request packet through unicast to the previous hop for the given multicast source and group. 3. From the last-hop router to the multicast source, each hop adds a response data block to the end of the request packet and unicasts it to the previous hop. 4. When the first-hop router receives the request packet, it changes the packet type to indicate a response packet. Then, it sends the completed packet through unicast to the querier. Configuration task list Task Enabling IP multicast routing Configuring multicast routing and forwarding Configuring static multicast routes Configuring a multicast routing policy Configuring a multicast forwarding range Configuring the multicast forwarding table size Tracing a multicast path Remarks Required Optional Optional Optional Optional Optional IMPORTANT: IP multicast does not support secondary IP address segments. Namely, multicast can be routed and forwarded only through primary IP addresses even if secondary addresses are configured on the ports. For more information about primary and secondary IP addresses, see Layer 3- IP Services Configuration Guide. Enabling IP multicast routing Before you configure any Layer 3 multicast functionality, you must enable IP multicast routing. 62

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62
First-hop router
—The router that directly connects to the multicast source is called the "first-hop
router".
Querier
—The router that sends multicast traceroute requests is called the "querier".
Introduction to multicast traceroute packets
A multicast traceroute packet is a special IGMP packet that is different from common IGMP packets in
that its IGMP Type field is set to 0x1F or 0x1E and its destination IP address is a unicast address. The
following types of multicast traceroute packets are available:
Query, with the IGMP Type field set to 0x1F,
Request, with the IGMP Type field set to 0x1F, and
Response, with the IGMP Type field set to 0x1E.
Process of multicast traceroute
1.
The querier sends a query to the last-hop router.
2.
After receiving the query, the last-hop router turns the query packet into a request packet by adding
a response data block (which contains its interface addresses and packet statistics) to the end of
the packet. It then forwards the request packet through unicast to the previous hop for the given
multicast source and group.
3.
From the last-hop router to the multicast source, each hop adds a response data block to the end
of the request packet and unicasts it to the previous hop.
4.
When the first-hop router receives the request packet, it changes the packet type to indicate a
response packet. Then, it sends the completed packet through unicast to the querier.
Configuration task list
Task
Remarks
Enabling IP multicast routing
Required
Configuring multicast routing and
forwarding
Configuring static multicast routes
Optional
Configuring a multicast routing policy
Optional
Configuring a multicast forwarding range
Optional
Configuring the multicast forwarding table size
Optional
Tracing a multicast path
Optional
IMPORTANT:
IP multicast does not support secondary IP address segments. Namely, multicast can be routed and
forwarded only through primary IP addresses even if secondary addresses are configured on the ports.
For more information about primary and secondary IP addresses, see
Layer 3— IP Services Configuration
Guide
.
Enabling IP multicast routing
Before you configure any Layer 3 multicast functionality, you must enable IP multicast routing.