MSMQ MultiCast (PGM) and garantied ordering

[Guest]

Hi,

I have eleven C# applications running on eleven different computers sending
packets to a MSMQ MultiCast configured queue (same address for all). Those
eleven senders also act as receivers.

Do all receivers receive the sent packets in the same order?

Thanks
Eric

 

[Frank Boyne]

Do all receivers receive the sent packets in the same order?

No. Even if you were using 'regular' transmission rather than multicast the
answer would be the same. MSMQ offers limited guarantees regarding message
order mostly to do with preserving order with respect to a single sender in
transaction mode, it doesn't offer overall guarantees about message delivery
order between multiple senders..

It is possible that systems on the same LAN segment might see the same
multicast messages at the same time and so might by chance happen to receive
packets in the same order. However, since Ethernet works by collision
detection not collision avoidance it is always possible that a collision
could cause one system to not see the original transmission because of a
collision with some other transmission which could result in a different
receive order.