pref syntax for RIPE-81++ (fwd)

	Two points:
- The <pref-type>=<value> list is enclosed between parentheses.
- ASxxx:ddd is equivalent to ASxxx (pref = ddd)
		Laurent

Point 1 because it is easier to parse
Point 2 because it is shorter
> 
> 
>  epg at merit.edu writes:
>   * 
> Okay, initial thoughts is this looks good and in line with what we discussed
> at Merit. However, somewhere we have lost the local linkid part which is
> what the interas attributes are for. I think just an oversight ?. 
> But if I assume this is added in like I think (?)
> we agreed as just the two ends of the link (perhaps ? host addresses) then
> I have just a couple of questions. If you could clarify this for me I think 
> for me at least we could wrap this into ripe-81++.
> 
> 			--Tony.
> 
> 
>   * > -------------------
>   * >  
>   * > interas-in and interas-out preference definition
>   * > 
>   * > 1. interas-in
>   * > 
>   * > interas-in: [from] neighborAS preference [accept] route
>   * > 
>   * > where 'preference' here is defined as:
>   * > 
>   * > <pref-type>=<value> [,<pref-type>=<value>]
>   * > 
> Just so I usderstand this means we could have something like this. I use
> addr<n> just as a psuedo representation for the linkid bit.
> 
> interas-in: from AS333 addr1 addr2 med-in=yes,pref=2 accept AS1104
> interas-in: from AS333 addr1 addr3 med-in=yes,pref=1 accept AS1104
> 
> Presumably this is okay. No idea if the inbound AS can implement this 
> but you could use this to show what you do in case of equal med metrics
> from both links. Or is the intention only to allow one or the other, although
> the definition doesn't seem to show this.
> 
>   * > <pref-type> has the following:
>   * > 
>   * > 	pref: 	the pre-configured preference for incoming routes same as 
>   * > 		defined in as-in attribute.  It's value is numeric number.
>   * > 		The lower the value, the higher preference.
>   * > 
>   * > 	med-in:	the usage of Multi_Exit_Discriminator metric from its 
>   * > 		neighbor's routing advertisement.  The value is yes or no.
>   * > 		Omission of the entry implies no usage of  MED from its
>   * > 		neighbor AS.
>   * > 
>   * > 2. interas-out
>   * > 
>   * > 	interas-out: [TO] neighborAS preference [ANNOUNCE] route  
> Slight correction     ^^                         ^^^^^^^^
>                       to                         announce
>   * > 
>   * > where 'preference' is defined as:
>   * > 
>   * > <pref-type>=<value> [,<pref-type>=<value>] 
>   * > 
>   * > <pref-type> has the following: 
>   * > 
>   * >         pref:   the pre-configured preference for outgoing routes same as
>   *  
>   * > 		defined in interas-in attribute.  It's value is numeric 
>   * >                 number.  The lower the value, the higher preference. 
>   * > 
>   * >         med-out: the value of Multi_Exit_Discriminator metric to advertis
>   * e 
>   * > 		routes to neighborAS.  If IGP metric is used to convert to 
>   * > 		MED, the value is 'IGP'.  Otherwise, the value is a numeric
>   * > 		number.  Omission of the entry implies no usage of MED when
>   * >                 advertising routes to its neighbor AS.
>   * > 
>   * > 3. Examples:
>   * > 
>   * > aut-num: AS237
>   * > interas-out: to AS690 <enss128> med-out=IGP announce AS237
>   * > interas-out: to AS690 <enss145> med-out=IGP announce AS237
>   * > 
> I sort of assume the enss bit is the link stuff ?
> 
>   * > aut-num: AS266 
>   * > interas-out: to AS690 <enss131> pref=1 announce {35/8, 128.14/16}
>   * > interas-out: to AS690 <enss129> pref=2 announce {35/8, 128.14/16}  
>   * > 
> Only question here is - is this not just as MED - can it be anything else ?
> 
>   * > aut-num: AS701
>   * > 
>   * > interas-out: to AS690 <enss134> med-out=2 announce {15/8,192.35.1/24}
>   * > interas-out: to AS690 <enss145> med-out=4 announce {15/8,192.35.1/24, 193
>   * .1.1/24}
>   * > 
>   * > aut-num: AS690
>   * > interas-in: from AS237 med-in=yes accept AS237
>   * > 
>   * > interas-in: <enss131> from AS266 pref=1 accept {35/8, 128.146/16}
>   * > interas-in: <enss129> from AS266 pref=2 accept {35/8, 128.146/16}
>   * > 
>   * > interas-in: from AS701 med-in=yes accept ANY 
>   * > 
>   * > 4. Expansion
>   * > 
>   * > The preference field by this design could be easily expanded in the futur
>   * e
>   * > when other metrics be used for policy decisions without changes to the al
>   * ready
>   * > defined ones.  For example, when tos/qos is widely used, one could just a
>   * dd
>   * > another field in the pref-type: tos=value.
>   * > 
> 


-- 
Laurent Joncheray,                                 E-Mail: lpj at merit.edu
    Merit Network Inc, 1071 Beal Avenue,           Phone:  +1 (313) 936 2065
    Ann Arbor, MI 48109, USA                       Fax:    +1 (313) 747 3745
"This is the end, Beautiful friend. This is the end, My only friend, the end" JM



-------- Logged at  Thu Jul 14 00:08:34 MET DST 1994  ---------