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josesalaz
Beginner

multicast 224.16.17.255

Hello guys,

We have configured cisco switch with igmp version 2 and we got a system that is taking the IP 224.16.17.255 for multicast. Is it a valid IP ending in 255? is it not a broadcast one?

A multicast IP that end in 255 is a valid IP for multicast?

 

Regards

 

Jose 

 

4 ACCEPTED SOLUTIONS

Accepted Solutions
Joseph W. Doherty
Hall of Fame Expert

I believe that's valid.  Rules are different for multicast IPv4 address blocks.

BTW, an unicast IPv4 ending with .255 doesn't have to be a broadcast IP, and conversely, other last octets can be broadcast IPs.

E.g.

10.1.2.255 /23 is a unicast IP

10.1.2.3 /30 is a broadcast IP

View solution in original post

Hello 

thanks for the response but in the unicast as you already showed, the broadcast is defined by the mask however, who define an IP will be broadcast or not in multicast?

 

View solution in original post

Perhaps a brief review of terminology might be helpful:

- unicast is an IP packet for which there is a single device as the recipient.

- broadcast is an IP packet for which the recipient is every device.

- multicast is an IP packet for which there is more than 1 recipient but fewer than all.

So there is no concept of broadcast when you are talking about multicast.

HTH

Rick

View solution in original post

5 REPLIES 5
Joseph W. Doherty
Hall of Fame Expert

I believe that's valid.  Rules are different for multicast IPv4 address blocks.

BTW, an unicast IPv4 ending with .255 doesn't have to be a broadcast IP, and conversely, other last octets can be broadcast IPs.

E.g.

10.1.2.255 /23 is a unicast IP

10.1.2.3 /30 is a broadcast IP

View solution in original post

Hello 

thanks for the response but in the unicast as you already showed, the broadcast is defined by the mask however, who define an IP will be broadcast or not in multicast?

 

View solution in original post

Perhaps a brief review of terminology might be helpful:

- unicast is an IP packet for which there is a single device as the recipient.

- broadcast is an IP packet for which the recipient is every device.

- multicast is an IP packet for which there is more than 1 recipient but fewer than all.

So there is no concept of broadcast when you are talking about multicast.

HTH

Rick

View solution in original post

you are right, my back