Browse Prior Art Database

Method for multicasting with alias IP address

IP.com Disclosure Number: IPCOM000191314D
Original Publication Date: 2009-Dec-29
Included in the Prior Art Database: 2009-Dec-29
Document File: 5 page(s) / 106K

Publishing Venue

IBM

Abstract

Disclosed is the Method for multicasting with alias IP address.

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Method for multicasting with alias IP address

    Multicast is a technique for one to many communication over an IP infrastructure. For multicasting, it is necessary for the hosts involved in communication to become a member of the multicast group with a specific group address.

Source-specific multicast (SSM) is a method of delivering multicast packets originating in only a specific source address S to any receiver that requests it.

    All the hosts who have joined the multicast group will receive a message sent to the group. The current method (SSM) specifies a method to filter receiving of multicast packets based on the source address in the multicast packet.

     The disclosure specifies a method to handle multicasting when the host has alias IP addresses configured dynamically and uses those alias addresses for communicating within the multicast group.

Problem:

    The Source Specific multicasting uses filter for receiving the multicast messages based on the known source address stored in the routing table. However, when the host has alias addresses configured and communicates with the alias IP address then the filtering of multicast messages fails.

This can be illustrated with the following example:

Consider hosts H1 with IP address IP1 and host H2 with IP address IP2. Host H1 and H2 are

part of a multicast group G. Lets consider 2 situations:

Host H1 is configured to receive multicast messages only from host H2 by specifying the IP address IP2 of the host H2 (Source specific multicasting). Host H2 is configured now with an alias IP address IP2-alias.

Now, if H2 sends out a multicast message with the alias IP IP2-alias,

then the host H1 does not receive it since the host is configured to receive multicast messages only from the host with IP address IP2.

Host H1 is configured to block multicast messages only from host H2 by specifying the IP address IP2 of the host H2 (Source specific multicasting). Host H2 is configured now with an alias IP address IP2-alias.

Now, if H2 sends out a multicast message with the alias IP IP2-alias,

then the host H1 will receive it since the host is configured to block multicast messages only from the host with IP address IP2.

Thus we see that in both the above situation, the filtering of multicast message fails.

The existing options:

     The host that uses Source address filtering for multicast messages must block/allow every alias IP address of the host to be blocked/allowed.

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Drawbacks of this solution:

    Blocking/Allowing every alias IP address from the host is inefficient. The source hosts might be configured with ali...