North American Network Operators Group
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Re: IGPs in use

  • From: bmanning
  • Date: Mon Oct 12 20:41:04 1998 
> > it probably depends on what you mean by "large".  If you mean "the 5 largest"
> > then yes, most use ISIS (but not all).  If you mean the 50 largest, then 
> > OSPF becomes much more prominent (that is, hardly anyone but the largest
> > ISPs use ISIS, at least from my discussions with dozens at my previous
> > and current employer).
> 
> Likely because their networks have been 'round the longest and ISIS was the 
> "IGP of choice" not long ago.  Also, some have/had requirements for ISO CLNS 
> ISIS routing support as well.
> 
> The use of ISIS shouldn't lead folks to believe that OSPF doesn't scale well 
> though.
>

	There might be something in there about OSPF beating ISIS out as
	a full Internet Std. back in the bad old days of the ISO wars.
	(But after the inital ISPs had already selected ISIS over OSPF!)
	Interestingly, ISIS has been revived and is being considered for
	advancement on the IETF Stds track by some vendors. It would be
	nice to have two IETF std IGP protocols instead of just one.
	(ditto EGPs :)

--bill