reliably detecting the presence of a bridge?

[Dave Taht <dave.taht () gmail com>]

I am curious if there is some sort of igmp or other form of message
that would reliably detect if a switch had a bridge on it. How could
deviceA detect deviceC was a bridge in this case?

deviceA  -> ethernet switch -> deviceB
                    ethernet switch -> deviceC with bridged wifi and ethernet

question came up in the context of:

http://lists.alioth.debian.org/pipermail/babel-users/2015-December/002231.html

--
Dave Täht
Let's go make home routers and wifi faster! With better software!
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