Re: looping of qpid routes

Ted Ross Thu, 15 Oct 2009 12:18:52 -0700

Which version of the software are you running?

-Ted


H. Charles Tang wrote:

Thanks folks for your help.
I think you're telling me that what we did for setting up two routes on a 
single link as follows should not cause a msg loop:
qpid-route route add host1:5000 host2:5000 amq.topic topic.foo
qpid-route route add host2:5000 host1:5000 amq.topic topic.foo

However what we have observed is different. The msg consumer couldn'tkeep up with the looping msg and eventually crashed.


Charles

--- On Thu, 10/15/09, Carl Trieloff <[email protected]> wrote:

From: Carl Trieloff <[email protected]>
Subject: Re: looping of qpid routes
To: [email protected]
Date: Thursday, October 15, 2009, 9:35 AM

Also, a header is used on the message to prevent loop
detection.

Carl.


Jonathan Robie wrote:

Bidirectional links are fine, and automatically detect

loops. Tree, star, or line topologies are fine too, and
bidirectional links between any pair of brokers are fine. A
ring topology is also possible, if only unidirectional links
are used.

Here's the rule:

For any pair of nodes A,B in a federated network,

there should be only one path from A to B. If there is more
than one path, message loops can cause duplicate message
transmission and flood the federated network. The topologies
discussed above do not have message loops. A ring topology
with bidirectional links is one example of a topology that
does cause this problem, because a given broker can receive
the same message from two different brokers. Mesh topologies
can also cause this problem.

Every message transfer takes time. For better

performance, you should minimize the number of brokers
between the message origin and final destination. In most
cases, tree or star topologies do this best.

Hope this helps!

Jonathan

H. Charles Tang wrote:

Have created 2 static routes as follows between

our 2 qpid daemons housed on two linux hosts respectively:

qpid-route route add host1:5000 host2:5000

amq.topic topic.foo

qpid-route route add host2:5000 host1:5000

amq.topic topic.foo

Does this create an infinite loop for a message

between 2 qpids? Our experiment confirmed the looping
scenario.

Then how does one create a bi-directional route?

or how do we interpret the following in the qpid
documentation:

"Routes are unidirectional. A single route

provides for the flow of messages in one direction across a
link. If bidirectional connectivity is required (and it
almost always is), then a pair of routes must be created,
one for each direction of message flow."

Finally does qpid (daemon) do loop

detection/handling?

Thanks.
Charles

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Re: looping of qpid routes

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