Re: [[e-mail]: Re: BGP4 stuff: Local Preference Computation]

[Curtis Villamizar <[e-mail]>]

In message <[e-mail]>om>, Yakov Rekhter writes:
> John,
> 
> > This should be fixed by reclassifying LOCAL_PREF as well-known mandatory.
> 
> "Mandatory" means that it *always* has to be present. LOCAL_PREF is not
> carried between external peers - just among the internal peers.

Good point.

> > [Other than the text being just plain wrong, the other possibility is that
> > "discretionary" is being used to mean something like "this is only
> > mandatory in some cases".  This is a terrible misuse of the language if
> > true, and should still be fixed, if necessary by inventing some new term
> > like "well-known sometimes-mandatory" or something.  (Note that the RFC
> > nowhere defines "discretionary" so we are left with the dictionary
> > definition, e.g. "left to discretion: exercised at one's own discretion".)]
> 
> Suggestions for better terminology area always appreciated (especially
> if accompanied by a "rough consensus").

How about in the RFC instead of

	mandatory	discretionary

we specify

	mandatory	discretionary	disallowed

and list IBGP and EBGP separately.

	  attribute	  IBGP				EBGP
	LOCAL_PREF    well-known mandatory        disallowed
	MED           well-known discretionary    well-known discretionary
	...

This affects a key attribute so we could set mandatory attribute bit
iff it is mandatory for both IBGP and EBGP and not change the protocol
any, just make the spec more clear.

> Yakov.

Curtis