The border router. It combines several provider lines for more capacity AND failover — if one provider drops, the others carry on. It's also where flood scrubbers and firewalls sit in the path. Chain: cross-connect → edge router → switches.
2U. 16× SFP28 25G + 2× QSFP28 100G, all generic. Multi-WAN with LACP bonding + BGP to carriers. Bond both 100G uplinks for headroom + failover. Inline appliances (scrubber/WAF) insert between this and the fabric.
