H3C Technologies H3C SecPath F1000-E - Manual (Page 501)

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{
Because loopback interfaces are virtual interfaces, you need to use the peer connect-interface
command to specify the loopback interface as the source interface for establishing BGP
connections.
{
Enable OSPF in AS 65009 to make sure that SecPath B can communicate with SecPath C
through loopback interfaces.
# Configure SecPath B.
<SecPathB> system-view
[SecPathB] bgp 65009
[SecPathB-bgp] router-id 2.2.2.2
[SecPathB-bgp] peer 3.3.3.3 as-number 65009
[SecPathB-bgp] peer 3.3.3.3 connect-interface loopback 0
[SecPathB-bgp] quit
[SecPathB] ospf 1
[SecPathB-ospf-1] area 0
[SecPathB-ospf-1-area-0.0.0.0] network 2.2.2.2 0.0.0.0
[SecPathB-ospf-1-area-0.0.0.0] network 9.1.1.1 0.0.0.255
[SecPathB-ospf-1-area-0.0.0.0] quit
[SecPathB-ospf-1] quit
# Configure SecPath C.
<SecPathC> system-view
[SecPathC] bgp 65009
[SecPathC-bgp] router-id 3.3.3.3
[SecPathC-bgp] peer 2.2.2.2 as-number 65009
[SecPathC-bgp] peer 2.2.2.2 connect-interface loopback 0
[SecPathC-bgp] quit
[SecPathC] ospf 1
[SecPathC-ospf-1] area 0
[SecPathC-ospf-1-area-0.0.0.0] network 3.3.3.3 0.0.0.0
[SecPathC-ospf-1-area-0.0.0.0] network 9.1.1.0 0.0.0.255
[SecPathC-ospf-1-area-0.0.0.0] quit
[SecPathC-ospf-1] quit
[SecPathC] display bgp peer
BGP local router ID : 3.3.3.3
Local AS number : 65009
Total number of peers : 1 Peers in established state : 1
Peer AS MsgRcvd MsgSent OutQ PrefRcv Up/Down State
2.2.2.2 65009 7 10 0 0 00:06:09 Established
The output information shows that SecPath C has established an IBGP peer relationship with
SecPath B.
3. Configure EBGP;
{
The EBGP peers, SecPath A and SecPath B (usually belong to different ISPs), are located in
different ASs. Typically, their loopback interfaces are not reachable to each other, so directly
connected interfaces are used for establishing BGP sessions.