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Fibre Channel (SAN)

Posts: 0

Brocade DCX Multicast Group Limit


I´m interested in multicast groups in a Brocade DCX, however I cannot figure if its limit for multicast groups is 255 or 256 groups.

On one hand there are a few (I think) datasheets, such as this one ( - page 3), where it is clearly stated that only 255 multicast groups are supported. On the other hand, if Fabric OS 6.1 and later are indeed compliant with the FC-SW-3 INCITS 384: 2004 standard (as stated in why exacly would the limit be 255 instead of 256 groups? Aren't multicast group id's in the range FFFB00 to FFFBFF (ie, 256 groups in total)?

I'd really appreciate if anybody could help me or least point out some more conclusive technical documentation.

Best regards,


Super Contributor
Posts: 644
Registered: ‎03-01-2007

Re: Brocade DCX Multicast Group Limit


-> ....why exacly would the limit be 255 instead of 256 groups?

I've such DOC that explained the used groups 1-255, but unfortunately cannot find at the moment.

I believe..... this restriction is caused by Maximum User Port Size / Capacity in the Fabric.

0 and 256 are Switch specific base Groups, and cannot be used.

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