Home > BSCI, CCNP > BSCI – Multicast notes

BSCI – Multicast notes

I was going over few of my multicast notes today.

Multicast is a smart(er) way to send the same traffic to many recipients (taking over Broadcast in IPv6). I’m not sure how big it is in the exam but here are few notes that I find important.

There are three ways to stream many receivers:
Unicast ->one to one
Broadcast->one to all
Multicast ->one to many

Multicast uses UDP and a Class D range of 224.0.0.0 – 239.255.255.255 and this is how the range split:
Globally Scoped – addresses 224.0.1.0 through 238.255.255.255 (Internet)
Limited Scope – addresses 239.0.0.0 through 239.255.255.255 (local organization\group)
Private Range – addresses 224.0.0.0 through 224.0.0.255 (used on local LAN)

IGMP (Internet Group Management Protocol) is a protocol used for multicasting, allowing clients to subscribe to multicast stream.
There are 3 versions of IGMP:
IGMPv1 – when a client stop listening the router still send stream
IGMPv2 – host send leave message when it doesn’t want to get stream
IGMPv3 – host send join request for the stream on the server

There are three group related concepts:
1. Router does not have to be a member of a multicast group to send stream to the group
2. Router must be a member of a multicast group to receive multicast data
3. If a packet is sent to a multicast group address, all members of the multicast group will receive it

PIM (Protocol Independent Mode) is configured on the router and set the way it will act when multicast stream will be presented:
PIM Dense mode – using flood and prune
PIM Spare mode – shared tree protocol, specify RP and all other routers access it
RP (Rendezvous Point) is a router elected to centralize multicasting in the network

I want to recommend some extra reading, though not CCNP related it has everything for the exam.

And as I always ask, if you have any comments or find mistakes don’t keep it to yourself.

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  1. February 23, 2010 at 9:42 am

    I’ll be using this when I get to that test. Thanks, Rofi.

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