Border Gateway Protocol - CCIE Routing and Switching Exam Certification Guide - page 440

you might want to minimize routing hops taken by having iBGP speakers advertise themselves
as the next hop instead of the IP address of eBGP speaker. To specify the next hop as itself, use
the BGP next-hop-self command. An example of the command is as follows:

router bgp 100
neighbor 1.1.1.1 remote-as 100
neighbor 1.1.1.1 next-hop-self

Local Preference Attribute
The local preference attribute indicates which path to use to exit the AS. It is a well-known
discretionary attribute used between iBGP peers and not passed on to external BGP peers. In
the IOS, the default local preference is 100; the higher local preference is preferred.

The default local preference is configured on the BGP router with an external path. It then
advertises its local preference to iBGP peers. An example of the local preference attribute where
Routers B and C are configured with different local preference is shown in Figure 9-6. Router
A prefers using Router C to route Internet packets because it has a higher local preference (400)
than router B (300).

Figure 9-6

BGP Local Preference

AS 300 Internet AS 200

Router D
s0: 2.2.2.1

Router E
s0: 3.1.1.1

eBGP eBGP

AS 100

Router B
1.2.1.1
local pref = 300

Router C
1.3.1.1
local pref = 400

iBGP

Router A

1.1.1.1