bgp path attributes...

and  preference... there is no way around it... they simply have to be memorized...

sister mary ignatius explains it all for you in the link below:

 http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml

weight

local preference

locally originated

as_path

origin code

lowest med

ebgp/ibgp

lowest igp to bgp next hop

age

lowest bgp router id

from  http://www.informit.com/articles/article.aspx?p=331613&seqNum=5

gonna have to get this book; russ white has his fingerprints on it

• Well known mandatory attributes; these attributes must be recognized by all BGP speakers, and must be included in all update messages. Almost all of the attributes impacting the path decision process, described in the next section, are well known mandatory attributes.
• Well known discretionary attributes; these attributes must be recognized by all BGP speakers, and may be carried in updates, but are not required in every update.
• Optional transitive attributes; these attributes may be recognized by some BGP speakers, but not all. They should be preserved and advertised to all peers whether or not they are recognized.
• Optional non-transitive attributes; these attributes may be recognized by some BGP speakers, but not all. If an update containing an optional transitive attribute is received, the update should be advertised to peers without the unrecognized attributes.

well known mandatory
as-path
next hop
origin

well know discretionary
local preference

atomic aggregate

optional transitive
aggregator
community

optional nontransitive
multi exit discriminator