Implementing exabgp 4.x built-in healthchecks for anycasted DNS: configuring health check intervals, rise/fall thresholds, withdraw-on-down behavior for automatic route removal on service failure, and multi-address-family BGP sessions for IPv4/IPv6 anycast announcements.
Implementing geographic fencing for nginx applications by ISP networks: using nginx geo module to whitelist IP subnets, aggregating prefixes by source AS from BGP looking glass, and generating dynamic ACL lists for regional access restrictions.
Building BGP looking glass on OpenBSD 6.6 using httpd and bgpd: configuring slowcgi for CGI support, setting up bgplg restricted socket, enabling ping/traceroute in chroot environment, and configuring dual IPv4/IPv6 BGP peering sessions for route lookups.
Understanding MPLS label swapping vs stacking: tracing label forwarding tables across router hops showing how labels are replaced at each hop using LDP distribution, with example traceroute output demonstrating label swapping through P/PE routers to destination.
Troubleshooting OSPF duplicate router IDs in VPLS networks: discovering 10-second route flapping caused by cloned PE router configuration, identifying router ID duplication, and understanding network-wide effects of duplicate router identifiers in MPLS service provider deployments.
