COMPLETE

Dual-ISP Failover (IP SLA)

Production-based lab - dual ISP links across two buildings with OSPF redistribution and IP SLA object tracking for automatic failover.

IP SLA Object Tracking OSPF Redistribution Route Maps Prefix Lists Dual ISP Failover Static routes

COVERAGE

TLS / L2 Extension

Transparent LAN Service simulated in CML
Main_TLS (primary) and Backup_TLS (failover)
Remote sites appear directly connected over L2
OSPF runs natively over the extended L2 domain

OSPF Area 0

Single area 0 across HQ, SiteA, SiteB
OSPF adjacencies over TLS links
Default route originated from Main Site
Internet reachability via Main Site uplink

IP SLA & Object Tracking

ICMP echo probes to Main_TLS gateway
ip sla schedule with continuous tracking
track ip sla reachability tied to default route
Floating static via Backup_TLS with higher AD

Failover Behavior

Primary default route removed when SLA probe fails
Backup route auto-installs via object tracking
OSPF reconverges through Backup_TLS path
Verified failover timing and convergence

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NOTES

This lab is based on a real project at Pace University - a new building needed dual-ISP connectivity with automatic failover. OSPF redistribution with route maps set cost-based preference for the primary ISP, and IP SLA tracking removed the primary route when the ISP gateway stopped responding, automatically failing over to the secondary provider.