Failover Mechanism Part-2
Dual POP Dual last mile Dual CE (DPDLDC)
This is second post related to fail over Mechanism ,In first post we have configured IP SLA to track the Primary link.Here we won’t be configuring track but will be having IBGP configured between CPE-1 and CPE-2. It’s topology is also Dual POP Dual last mile Dual CE (DPDLDC).It provides redundancy both for WAN connectivity as well as LAN connectivity.
Here we will be controlling the Traffic from CPE. ISP is very much transparent and is not influencing traffic in this scenario.

Topology.
Here we wont’t track the WAN IP as in fail over Mechanism in last post but will have IBGP running between CPE-1 and CPE-2
Failover Mechanism —
1. Outgoing Traffic from CPE wan is controlled using Local-Preference (Higher LP preferred)
2. Incoming traffic to CPE is controlled using AS Path Prepend attribute of BGP at secondary( lower as path count , better path)
Normal Scenario
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Primary WAN link is up .HSRP running on CPE-1 towards LAN is active state. CPE-1 has routes to other location from both EBGP and IBGP but will be preferred via PE1 (High Local Preference configured ).Whereas AS prepend is configured on CPE-2 Continue reading




Another, similar, line of thinking came up at the mic during a discussion around whether