90
•
Upstream interface—Also called the “proxy interface.” A proxy interface is an interface on which
IGMP proxying is configured. It is in the direction toward the root of the multicast forwarding tree.
An upstream interface acts as a host that is running IGMP. It is also called the “host interface.”
•
Downstream interface—An interface that is running IGMP and is not in the direction toward the
root of the multicast forwarding tree. A downstream interface acts as a router that is running IGMP.
It is also called the “router interface.”
A device with IGMP proxying configured maintains a group membership database, which stores the
group memberships on all the downstream interfaces. Each entry comprises the multicast address, filter
mode, and source list. Such an entry is a collection of members in the same multicast group on each
downstream interface.
A proxy device performs host functions on the upstream interface based on the database. It responds to
queries according to the information in the database or sends join/leave messages when the database
changes. On the other hand, the proxy device performs router functions on the downstream interfaces by
participating in the querier election, sending queries, and maintaining memberships based on the
reports.
Multi-instance IGMP
IGMP maintains group memberships on a per-interface basis. IGMP in a VPN instance handles protocol
packets based on the VPN instance on the interface. Upon receiving an IGMP packet, the router
determines the instance to which the message belongs and handles the message within the instance. If
IGMP running in a VPN instance needs to exchange information with another multicast protocol, the
router informs the other multicast protocol only within the VPN instance.
Protocols and standards
•
RFC 1112,
Host Extensions for IP Multicasting
•
RFC 2236,
Internet Group Management Protocol, Version 2
•
RFC 3376,
Internet Group Management Protocol, Version 3
•
RFC 4605,
Internet Group Management Protocol (IGMP)/Multicast Listener Discovery (MLD)-Based
Multicast Forwarding (“IGMP/MLD Proxying”)
IGMP configuration task list
Complete these tasks to configure IGMP:
Task
Remarks
Configuring basic functions of
IGMP
Required
Optional
Optional
Configuring a multicast group filter
Optional
Configuring the maximum number of multicast groups
that an interface can join
Optional
Configuring IGMP message options
Optional
Configuring IGMP query and response parameters
Optional
Summary of Contents for A5500 EI Switch Series
Page 12: ...xii Conventions 425 Index 427 ...
