Cache
Ravel evaluation plan (SOSR 16)
metric to compare
  - routers and switches to rapidly respond to failure, restoring
connectivity in 10s of milliseconds
- Google WAN: Google dta centers world-wide, more than 143,000
OpenFlow rules installed in these switches.
- Stanford University Backbone Network: more than 757,000
forwarding entries, 100+ VLANs and 1,500 ACL rules.
properties
  - loops and black holes
- reachability: basic reachability policy, reachability via waypoint,
path length constraints
- backup routes have identical reachability (same path path length)
- reachable sets: customer VMs can access VMs
scenarios
view update
shallow embedding, deep embedding