We are utilizing Mzima Network.
It uses metropolitan SONET rings connected to multiple Tier-1 backbone providers.
We have multiple fiber optic (gigE 1000Mbit/s) connections to our upstreams as well as OC 48 Backbone.
It features:
Fully-redundant architecture
Multi-gigabit backbone with over 20 Gbps of transit/peering capacity
SONET transit connections for self-healing fault-tolerance
Multi-layer network design
BGP best-path routing
Automatic detection and re-routing around network failures
Open peering policy allowing for local data delivery
Carrier fault-tolerance
Non-oversubscribed bandwidth
Quality of Service monitoring and analysis