One of those topics that is really fundamental to passing Cisco exams and labs or more importantly, predicting the behavior of BGP, is knowing the BGP route selection process well.
Following is a summary for quick reference.
1. Next_Hop: The next hop of the BGP route has to be in the routing table else if it is unreachable, the route is ignored.
2. Pre-bestpath Cost: If the pre-bestpath cost attribute is present, choose the route with the lowest cost value, if they are the same, the lowest community.
3. Weight: Cisco proprietary, local significant attribute where the largest is prefered.
4. Loc_Pref: If the weights are the same, choose the path with the highest local preference.
5. Local Originated: Routes that were locally originated with network statement, aggregated or redistributed.
6. AS_PATH: Next compare the as-path length and prefer the route with the shortest AS_PATH length.
7. ORIGIN: Choose the route with the lowest origin type if the AS_PATH lengths are the same. IGP<EGP<INCOMPLETE
8. MED: If the origin types are the same, choose the route with the lowest MED value. This will only be compared for routes from the same AS or if bgp always-compare-med is enabled, for all routes.
9. EBGP/iBGP: Prefer EBGP routes over IBGP routes if the routes have the same MED value.
10. IGP: At this point if there are still multiple routes prefer the route with the shortest route to the NEXT_HOP. The IGP will have already determined the shortest path to the next-hop.
11. Cost: If the cost attribute is present not configured to be ignored, choose the lowest cost.
12. Multipath: If multipath is enabled, multiple paths that match up to this point will be installed.
13. Oldest: If multiple external routes remain, choose the oldest one, thus avoids propagating a flapping route. To overwrite this, this step can be ignored with bestpath compare router-id.
14. Router_ID: If multiple routes still exist, the BGP ROUTER_ID will be a tiebreaker. Choose the route advertised by the BGP peer with the lowest Router_ID. If RR present, the originator ID is used.
15. Cluster Length: Minimum RR cluster length is compared next.
16. Lowest Neighbor: Last, the path from the lowest neighbor address.
Richard Bannister made a great post on the topic that in detail illustrates the algorithm in a flow-chart:
http://rbcciequest.wordpress.com/2008/02/27/bgp-path-selection/
And then there is the well known Cisco documentation:
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml
Preview of Richard Bannister’s flow-chart:
BGP scanner process monitors the next hop of installed routes to verify next-hop reachability. It is also responsible to select, install, and validate the BGP best path. By default, the BGP scanner is used to poll the RIB for this information every 60 seconds. During the 60 second time period between scan cycles, Interior Gateway Protocol (IGP) instability or other network failures can cause black holes and routing loops to temporarily form.
BGP scan process is also responsible for the checks to determine whether the conditional advertisement should or should not advertise the conditional route. It also checks whether route dampening information needs to be updated.
bgp scan-time
There is also a VPN4 equivalent that is configured under the VPN4 address family and the syntax is slightly different. By default it runs every 15 seconds.
bgp scan-time import
Also see:
http://www.cisco.com/en/US/docs/ios/iproute/configuration/guide/irp_bgp_adv_features_ps6350_TSD_Products_Configuration_Guide_Chapter.html#wp1056233
http://www.cisco.com/en/US/docs/ios/12_0t/12_0t7/feature/guide/VPN_EN.html#wp1045721
OEQ to be tested on SP from 4th Jan 2010. Guess I will have some use for that extra month after all. Just glad I worked it into the study schedule. Now, the next question, how to prepare for this and what to expect. If the RS feedback regarding the OEQ is anything to go by then it should be a walk in the park. Famous last words…
Call me crazy, but I am glad it has finally made it.
http://www.cisco.com/web/learning/le3/ccie/sp/lab_exam.html
Still nothing on:
http://www.cisco.com/web/learning/le3/ccie/announcements/index.html
and
https://learningnetwork.cisco.com/community/certifications/ccie_service_provider
Very interesting track that is making the rounds in the usual gossip corners. Now I have already decided SP will be my last CCIE (excluding CCDE), but Data Center would be very tempting. Wife would kill me though 
Apparently it will replace/consolodate the current Storage track which I think is a good idea. Storage in it self is not very appealing, but Data Center, if truly reflecting current and future real world Data Centers, then Yes, it is bound to be a winner.
In summary I would expect something to the effect of CCIE storage + CCIE RS less the routing. Possible devices:
Cat: 65xx, 49xx, 45xx, some smaller cats
Nexus: 5k, 7k
MSD 9xxx
Cisco ACE?
ACS
Realistically we will probably not see the high end devices and even then it will be a difficult track to prepare for due to the hardware.
Some earlier comments:
http://www.facebook.com/topic.php?uid=75717837879&topic=8511
I never thought this would ever happen: RS numbers officially dropping, SP taking the lead. Probably just a glitch in the system while the cheaters/vendors/360 program catch up. I wonder whether the 360 ads will change their 1.2 pass ratio. From the latests stats: 71 New SP ccie’s of which 20 were RS holders. That trend is slightly down from Feb09 when it was 24:62. If CCIE was a code on the stock exchange, I would expect to see a spike.
http://www.cisco.com/web/learning/le3/ccie/certified_ccies/worldwide.html
http://www.networkworld.com/community/node/48678
http://www.ccie18473.net/wwccies/wwccies.htm
