Internet Group Management Protocol (IGMP) | 459
22
Internet Group Management Protocol (IGMP)
Internet Group Management Protocol (IGMP) is supported on platforms:
e c s z
Multicast is premised on identifying many hosts by a single destination IP address; hosts represented by
the same IP address are a multicast group. Internet Group Management Protocol (IGMP) is a Layer 3
multicast protocol that hosts use to join or leave a multicast group. Multicast routing protocols (such as
PIM) use the information in IGMP messages to discover which groups are active and to populate the
multicast routing table.
IGMP Implementation Information
• FTOS supports IGMP versions 1, 2, and 3 based on RFCs 1112, 2236, and 3376, respectively.
• FTOS does not support IGMP version 3 and versions 1 or 2 on the same subnet.
• IGMP on FTOS supports up to 512 interfaces on E-Series, 31 interfaces on C-Series and S25/S50,95
interfaces on the S4810, S55, and S60and an unlimited number of groups on all platforms.
• Dell Force10 systems cannot serve as an IGMP host or an IGMP version 1 IGMP Querier.
• FTOS automatically enables IGMP on interfaces on which you enable a multicast routing protocol.
IGMP Protocol Overview
IGMP has three versions. Version 3 obsoletes and is backwards-compatible with version 2; version 2
obsoletes version 1.
IGMP version 2
IGMP version 2 improves upon version 1 by specifying IGMP Leave messages, which allows hosts to
notify routers that they no longer care about traffic for a particular group. Leave messages reduce the
amount of time that the router takes to stop forwarding traffic for a group to a subnet (leave latency) after
the last host leaves the group. In version 1 hosts quietly leave groups, and the router waits for a query
response timer several times the value of the query interval to expire before it stops forwarding traffic.
To Next Page
Loading...
