TTL Scope Control
Assign TTL thresholds to each link:
- if (packet TTL < threshold) drop packet
- recall no ICMP time exceeded for multicast
TTL Threshold Conventions:
- 0: same host, 1: same subnet
- 15: same site, 63: same region (west coast)
- 127: worldwide, 191: worldwide, limited bw
- 255: unlimited scope