Update to Matters officially assigned IANA port of 5540

[aronrosenberg]

Problem

Update the code to use the new officially assigned port number 5540 from IANA.

Summary of Changes

Change all instances of the old port number 11097 to 5540 in the code, documentation, examples and test scripts

Fixes https://github.com/CHIP-Specifications/connectedhomeip-spec/issues/1777

Tracks the spec PR found here: https://github.com/CHIP-Specifications/connectedhomeip-spec/pull/3247

Testing

• Manually tested by compiling and checking advertisements and listening ports
• This is a breaking change and requires all sides to update as the port number has changed

[msandstedt]

I thought the IANA assignment was for group multicast communication. The sdk isn't currently using 11097 for group multicast communication. It's using it as a kludge in the absence of mDNS discovery.

Why then would we change it?

[andy31415]

I thought the IANA assignment was for group multicast communication. The sdk isn't currently using 11097 for group multicast communication. It's using it as a kludge in the absence of mDNS discovery.

Why then would we change it?

Do we have a link to the official assignment? I thought assignment is generally "for project/application" so it may not be fixed to only group multicast (we own the port to listen on in general ... cannot say we only listen for multicast).

[aronrosenberg]

Official assignment was communicated from IANA this morning to myself and Stuart Cheshire. It will show up in the next published updates to the Port and Services list (a few days). Note that 11097 was just a number chosen at semi-random (it was one value higher than the previous IANA allocations for Weave). Any usage of that value is not allowed officially and thus we requested a proper value for Matter use. Group Multicast is the primary reason for the allocation, but this also allows us to cleanly set the default listen port to 5540 for normal UDP/TCP even though they can be discovered via mDNS.

You can see the published IANA registrations here.