Again, you are looking at portions of the standard related to internetworking between 802.5 Token Ring, FDDI, and Ethernet. Source Routing was a bridging mechanism supported on 802.5 Token Ring and FDDI, but is no longer used.
This topic (as well as most of the questions you have been raising lately) is discussed in Chapter 3 and 6 of "The Switch Book". I strongly suggest you obtain a copy and read it before throwing questions out "into the aether" for others to educate you.
-- Rich Seifert Networks and Communications Consulting 21885 Bear Creek Way (408) 395-5700 Los Gatos, CA 95033 (408) 228-0803 FAX
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