On Jan 11, 2018, at 9:47 AM, Noel Chiappa via cctalk
<cctalk at classiccmp.org> wrote:
...
Like I said, we did 'borrow' some idea from IS-IS, in particular the sequence
number thing - but that may have come direct from Radia's paper:
Radia Perlman, "Fault-Tolerant Broadcast of Routing Information", Computer
Networks, Dec. 1983
Yes, that documents work she did at DEC early on, while developing the original link state
routing proposal that was intended to be Phase IV but was set aside as "too
complicated".
I don't recall where the concept of a designated
router stuff came from, if
IS-IS was any influence there or not.
Designated router was part of DECnet Phase IV, so early 1980s. OSPF does it in a
fundamentally different way: DECnet aimed to be deterministic, OSPF aims to be stable.
The consequence is that in DECnet a given topology always has the same designated router
no matter the sequence in which things came together, while in OSPF the designated router
depends the order in which things happened. There are arguments for either approach; in
routers it doesn't matter much.
paul