Information Technology Reference
In-Depth Information
Here is a description of the command-line options:
GrpAddr
: Required parameter whose value is the group IP address
GrpMask
: Required parameter whose value is the subnet mask of the multicast scope
ScopeName
: Required parameter whose value is the name of the multicast scope
For example, to create a multicast scope with an IP address of
239.1.1.1
, a subnet mask of
255.255.255.224
, and a name of
My Favorite Scope
, use the following command:
> netsh routing ip add scope 239.1.1.1 255.255.255.225 "My Favorite Scope"
How It Works
Multicasting is the process of delivering a data packet to a group of hosts rather than to a single
host on a TCP/IP-based network. When data must be delivered to multiple hosts, multicasting
is preferred over unicasting or broadcasting. Broadcasting is nonroutable and unicasting is less
efficient, since it requires multiple data packets.
■
Note
For an explanation of the IPv4 multicasting protocol, see the Microsoft TechNet article
“What Is IPv4 Multicasting” (
http://technet2.microsoft.com/WindowsServer/en/Library/
a8ae022c-a00b-4b0f-ba59-3b476853025c1033.mspx
).
RRAS uses IGMP as an IP routing protocol component. Router interfaces are configured in
one of two operating modes: IGMP router mode or IGMP proxy mode. The purpose of IGMP
router mode is to forward multicast traffic in a single-router intranet. The purpose of IGMP
proxy mode is to connect a single-router intranet to a multicast-capable intranet or the
Internet.
See Also
Microsoft TechNet: “Understanding Multicasting” (
http://technet2.microsoft.com/
WindowsServer/f/?en/Library/93175810-b5bf-4c45-b962-6bc45c3012641033.mspx
). This
article contains information on the multicast routing process.
Microsoft TechNet: “Using the IP Multicasting Utilities” (
http://technet2.microsoft.com/
WindowsServer/f/?en/Library/094959ee-b18c-4e3c-b8e2-4511cde49d301033.mspx
). This
article describes utilities that can diagnose and troubleshoot multicast issues.
Recipe 5-11 for more on IGMP, the protocol required to support multicasting.
5-6. Managing the IP Routing Table and Static Routes
Problem
You want to view entries in the IP routing table.
