This article is from the Token Ring FAQ, by James Messer James@NetworkUptime.com with numerous contributions by others.
In normal token ring operation, a station sending information holds
the token until the sending data circles the entire ring. After the
sending station strips the data from the ring, it then issues a free
With Early Token Release (ETR), a token is released immediately
after the sending station transmits its frame. This allows for
improved performance, since there is no delay in the downstream
neighbor waiting for the token.
ETR is only available on 16 megabit rings. Stations running ETR can
coexist with stations not running ETR.