BGP Administrative Distance (Preference)
Cisco
20 (eBGP) and 200 (iBGP)
Huawei
255
Juniper
170
Nokia
170
BGP Cheat Sheet
By Gokhan Kosem,
www.ipcisco.com
BGP General
Protocol of Internet
Path Vector Protocol
TCP port 179
TCP Handshake Mechanims
BGP Key Terms
Autonomous System
A Logical Domain under
a single administration.
External BGP (eBGP)
BGP adjacency between
ASs.
Internal BGP (iBGP)
BGP adjacencies within
an AS.
Path Attributes
Different parameters
used for directing paths.
Route Reflector(RR)
A central device used to
avoid full
-mesh IBGP.
BGP Confederations
Like RR, Sub AS to
reduce IBGP Perrings.
BGP Best Path Selection
1.
Weight (Highest)
2.
Local Preference (Highest)
3.
Self-Originated
4.
AS Path (Shortest)
5.
Origin (IGP over EGP)
6.
MED (Lowest)
7.
External (eBGP over iBGP)
8.
IGP Cost (Lowest)
9.
Multiple paths
10.
eBGP Peering (Oldest)
11.
Router ID (Lowest)
12.
Cluster List (Minimum)
13.
Neighbor address (Lowest)
BGP Message Types
Open messages
Update messages
Keepaliev messages
Notification messages
BGP Path Attributes
Well
-Known Mandatory
AS_PATH, Origin,
Next_Hop
Well
-Known Discretionary
Local
-Pref,
Atomic_Aggregate
Optional Transtive
Aggregator, Community
Optional Non
-transtive
Multi
-Exit-Discriminator
(MED), Originator_ID,
Cluster List
