Multicast IP Addresses Overview

One of the differences between unicast and multicast IP addresses, is that unicast IP addresses represent a single network device while multicast IP addresses represent a group of receives. IANA has reserved the class D range to use for multicast. The first 4 bits in the first octet are 1110 in binary which means that we have the through range for IP multicast addresses.

multicast class D range

Some of the addresses are reserved however and we can’t use them for our own applications.

The – range has been reserved by IANA to use for network protocols. All multicast IP packets in this range are not forwarded by routers between subnets. Let me give you an overview of reserved link-local multicast addresses, I’m sure you recognize some of the protocols:

Address Usage All Hosts All Multicast Routers Unassigned DVMRP Routers OSPF Routers OSPF DR/BDR Router ST Routers ST Hosts RIPv2 Routers EIGRP Routers Mobile Agents DHCP Server / Relay All PIM Routers RSVP Encapsulation All CBT Routers Designated SBM All SBMS VRRP – 255 Unassigned

You probably recognized OSPF ( and, RIPv2 ( and EIGRP (  Once you dive more into multicast you will also encounter PIM (Protocol Independent Multicast) with

IANA also reserved the /24 range for certain applications. Everything in the /24 range can be routed however, unlike the /24 range. Here’s an overview:

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Forum Replies

  1. for 224 range : One such example could be “ospf hello” which is not a user traffic but traffic among routers and does not require to be routed.
    where-in for 239 range …it is a multicast user traffic . thats how IANA has separated both range for multicast…is that correct to say?

  2. Abhishek,
    This is generally correct, with a couple of clarifications:

    1. When you say “224 range” specifically, that is which is the range reserved for traffic on the local segment only. Any 224 network higher, say has no special significance.

    2. The is not really defined as user traffic vs router traffic. Its significance is that it is available for private organizational use. Think of this as being the same thing as, or for private IPv4 spaces.

  3. Awesome. clears the doubt now.

  4. Hi Andrew ,
    A doubt on higher level …
    I was trying to understand connection between AND in MULTICAST concept.
    So any video server, once connects to router (so there must be some app that pump video traffic towards router) and router once configured “with respective config” , start sending traffic towards IP And then hosts (typically equipped with an application such as VLC ) that are configured with “related host config” get this feed via that multicast router.

    1. So Is it always or we can change this IP?
    2. where does 224.
    ... Continue reading in our forum

  5. Abhishek,

    1. The range is entirely reserved for private, organization use. This means, the range from - can be used anyway you like–so long as the traffic stays within the bounds of a private address of a company. This means your video server could be configured to use any address between and if your goal to ensure you are using the “private” multicast range.

    2. For, I was just trying to make the point that when you originally said “224 range” that in order for your statement to be accura

    ... Continue reading in our forum

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