GTPv1 vs GTPv2
GTPv1-C was defined for 2G/3G packet core; GTPv2-C replaced it for LTE with a cleaner IE encoding and TEID handling. GTP-U kept a single version. Roaming and legacy fallback keep both control-plane versions in production.
| Attribute | GTPv1 | GTPv2 |
|---|---|---|
| Generation | 2G / 3G packet core | LTE (SGW / PGW) |
| Reference | 3GPP TS 29.060 | 3GPP TS 29.274 |
| IE format | TLV, fixed types | TLIV with instance byte |
| Bearer model | PDP context | EPS bearer |
| Interworking | Gn / Gp | S5 / S8 |
Verdict
A GTP firewall spec that only names "GTP" is ambiguous. FS.20 covers both versions; deployments must decode both, correlate v1 PDP contexts with v2 bearers at handover, and screen for cross-version smuggling.