Failover Mechanism Part- 3
How should Fail over need to be implemented if CPE router is common for
primary and secondary link ? Answer for the same can be found in this post.
This scenario may be refer as DPDLSC (DUAL POP DUAL LAST MILE SINGLE CPE)
Just to mention that traffic control is being done from CPE,ISP is very
much transparent and is not influencing traffic in this scenario.

Considering the above Topology.
FAILOVER MECHANISM —-
1. Outgoing Traffic from CPE is controlled using Local Preference (Higher local Preference, better path)
2. Incoming Traffic to CE is controlled using As Path Prepend ( lower as path count , better path)
NORMAL SCENERIO
Primary link is up ,Local preference is high for primary link than secondry and also there is no as-prepend as in secondry
OUTGOING TRAFFIC >>> LAN>CPE>PE1
INCOMING TRAFFIC >>> PE1>CPE>LAN
PRIMARY WAN LINK DOWN(PE1-CPE link down)
OUTGOING TRAFFIC >>> LAN>CPE>PE2
INCOMING TRAFFIC >>> PE2>CPE>LAN
RELATED CPE CONFIGURATION
router bgp 64520
bgp log-neighbor-changes
network 10.0.0.0 mask 255.255.0.0
neighbor 172.10.1.1 remote-as 9730
neighbor 172.10.1.1 description PRIMARTY
neighbor 172.10.2.1 remote-as 9730
neighbor 172.10.2.1 description SECONDRY
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