IP Multicast

General

• http://en.wikipedia.org/wiki/Multicast
• IP Multicasting: Concepts, Algorithms, and Protocols
• Designing for Multicast Operation with IGMP: A Tutorial Description
• IP-Multicasting Technology Part I: History and Overview
• Multicast is a layer-3 (IP) feature (Multicast Routing).
• Multicast Switching is a complementary technology at layer-2
  this is generally called: “IGMP snooping”

• IGMP snooping

Essentially, IGMP snooping is a layer 2 optimization for the layer 3
IGMP protocol. IGMP snooping takes place internally on switches and
is not a protocol feature.

• IGMP is doing the same thing in IPv4 as “Multicast Listener Discovery” (MLD) in ICMPv6
• Active IGMP Snooping = “IGMP proxy” = RFC 4541
  “Considerations for Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Snooping Switches”
• the Generic Attribute Registration Protocol (GARP) protocol was used by the application “GARP Multicast Registration Protocol” (GMRP). Today most switches prefer IGMP-Snooping over GMRP.

IP Multicast addresses are Class D subnet (first bits: 1110):

224.0.0.0/4    (224.0.0.0-239.255.255.255)

with reserved:

  224.0.0.0/24  network control traffic (routing protocols like OSPF)
  224.0.0.1     all-hosts = all systems on subnet
  224.0.0.2     all-routers = all multicast routers on a subnet
  224.0.0.5     OSPF All Routers
  224.0.0.6     OSPF Designated Routers
  224.0.0.9     RIP2
  224.0.1.1     NTP


  224.0.1.0/24  Internetwork Control Block (RSVP, DHCP) 

  224.1.0.0/16  ST Multicast Groups

  224.2.0.0/16  SDP/SAP Block

  239.0.0.0/24  reserved for boundaries

IP to MAC mapping

According to IPv4 multicast standards, the MAC destination multicast
address begins with 01:00:5e and is appended by the last 23 bits of
the IP address.
01:00:5e:00:00:00-01:00:5e:7f:ff:ff

224.128.64.32 -> 01:00:5e:00:40:20

• MBONE

• IGMP

• wikipedia → Protocol Independent Multicast (PIM)
• PIM Sparse Mode

• Wikipedia → Distance Vector Multicast Routing Protocol (DVRMP)

http://www.novell.com/documentation/zenworks65/index.html?page=/documentation/zenworks65/dmadmin/data/a7jl098.html

The name of the multicast session. Each workstation joining the
session uses the same value for this parameter.

NOTE:  The name must be unique among concurrent multicast sessions.
It is hashed by the imaging engine to produce a Class D IP address
for the multicast session. To facilitate troubleshooting (wire
sniffing), all Desktop Management Workstation Imaging multicast
addresses start with 231. For example, the session name doug produces
the multicast address 231.139.79.72.

• Reliable multicast
• Pragmatic General Multicast = PGM
• http://code.google.com/p/openpgm/
• http://developer.novell.com/wiki/index.php/OpenPGM_Concepts/Transport
• RML = Reliable Multicast Library → http://www.land.ufrj.br/tools/rmcast/rmcast.html

• IP Multicast support page
• Cisco TechBrief: Internet Protocol IP Multicast Technology
• Cisco Group Management Protocol (CGMP)

• http://packeth.sourceforge.net/
• http://www.hping.org/
• http://nemesis.sourceforge.net/manpages/nemesis-igmp.1.html