A building-permits desk is reading a PE forwarding table while trou…

Question

A building-permits desk is reading a PE forwarding table while troubleshooting an L3VPN and must interpret how VPN labels were assigned. At a conceptual level, what does per-prefix label allocation mean?

Accepted Answer

The PE allocates a distinct VPN label for each advertised prefix (or FEC) rather than aggregating many prefixes under one label — Per-prefix labeling is like giving every package its own sticker instead of one sticker for the whole truckload. More granularity in the forwarding table, more labels to track when you troubleshoot. Knowing the allocation mode tells you why CEF shows many VPN labels or just a few.

Answer

One transport label is shared by the entire MPLS core regardless of destination PE

Answer

Each VRF receives exactly one label that never changes when prefixes are added or withdrawn

Answer

Labels are allocated only on P routers, so PE CEF shows unlabeled VRF lookups only

A building-permits desk is reading a PE forwarding table while troubleshooting an L3VPN and must interpret how VPN labels were assigned. At a conceptual level, what does per-prefix label allocation mean?

Short Explanation

Full Explanation