Dynamic routing protocol BGP:
of As is a 16-bit number, 1-65535 value
used when the BGP one of the following conditions is present:
. 1) allows the AS packets to other autonomous systems to pass through it reaches
2) a plurality of external connection, a plurality of operation between supplier: has a plurality of connection to the Internet
3) must enter and exit the aS data flow control
is not used when the BGP one of the following conditions exist:
1) only a single connection to the internet or aS
memory 2) and a router CPU performance is poor
3) inability embodiment BGP routing or path selection filter
4) is low between autonomous system bandwidth
comprising the neighbor table, forwarding BGP routing table
BGP neighbors belong to different AS called the EBGP
BGP belong to the same a AS, (IBGP neighbors) does not require direct connection between them, called IBGP.
The main BGP configuration commands:
Router BGP 64512-65535 (activation BGP, a router can only belong to one AS
Bgp route-the above mentioned id 1.1.1.1 meaning and the same for OSPF
Neighbor ip remote-as 65001 (activation BGP neighbor session
Network ip sub-segment mask network mask (declared routing
Main contents BGP attributes:
of As-path (AS path
the Next-Hop (next hop
Local preference (local precedence setting 100, the greater the priority
Med (multi-exit discriminator attribute
Weight (weight attribute
BGP simple configuration:
R1: as 65001 (12.1.1.1 1.1.1.1
R2: as 65002 (12.1.1.2 23.1.1.2 2.2.2.2
R3: as 65003 (23.1.1.3 3.3.3.3
R1(config)#
interface e0/1
ip address 12.1.1.1 255.255.255.0
no shutdown
interface lo0
ip address 1.1.1.1 255.255.255.0
no shutdown
router bgp 65001
neighbor 12.1.1.2 remote 65002
network 12.1.1.0 mask 255.255.255.0
network 1.1.1.1 mask 255.255.255.0
R2(config)#
rotuer bgp 65002
neighbor 12.1.1.1 remote 65001
neighbor 23.1.1.3 remote 65003
network 12.1.1.0 mask 255.255.255.0
network 23.1.1.0 mask 255.255.255.0
network 2.2.2.2 mask 255.255.255.0
R3(config）#
router bgp 65003
65002 Remote 23.1.1.2 neighbor
Network 23.1.1.0 mask 255.255.255.0
Network mask 255.255.255.0 3.3.3.0
View route show ip route
View BGP show ip bgp