Information Technology Reference
In-Depth Information
To delete (unbind) the IGMP protocol from a particular interface, use this command:
> netsh routing ip igmp delete interface InterfaceName=
<InterfaceName>
InterfaceName
is a required parameter.
How It Works
IGMP is the protocol responsible for maintaining entries in the multicast forwarding table.
There are two possible ways to configure IGMP: in router mode or proxy mode.
Configure IGMP in
router mode
if you want your system to listen for IGMP membership
report packets and track group membership. Configure IGMP in
proxy mode
if you just want to
forward membership report messages to a device or interface running in router mode.
There are three versions of IGMP that are relevant in Windows Server 2003:
Version 1:
Hosts can join multicast groups. There are no messages generated when a
host leaves a group. Routers use a time-out period to discover which groups are no
longer relevant and which should be dropped.
Version 2:
Version 2 adds to version 1 by generating messages when a host leaves a group.
Version 3:
Hosts can specify a list of hosts from which they want to receive traffic. Traffic
from all other hosts will be blocked.
There are a number of terms that are used in this recipe that may not be familiar to many
system administrators and therefore deserve a definition:
Robustness variable:
Indicates the relative quality of the subnet that the interface is
connected to. Lossy subnets have high robustness variables. Microsoft recommends
that you set this variable to a value of 2 or higher for efficient operation.
Query interval:
The duration between IGMP queries sent by the router.
Query response interval:
Specifies the amount of time that the router will wait before it
gives up on its general query response.
Last member query interval:
Specifies the amount of time after which the router will
give up waiting for a response to a query focused at a specific group.
Startup query interval:
Specifies the amount of time between successive general query
messages that a IGMP router sends when it starts.
Startup query count:
Specifies the number of general query messages that an IGMP
router sends when it starts.
Last member query count:
Specifies the number of queries that a router sends at a
particular group before it assumes there are no remaining hosts in the group on a partic-
ular interface.
