TEIDs
TEID, or Tunnel Endpoint Identifier, is a field within the control plane signaling messages of certain network protocols, most notably within the Gateway General Packet Radio Service (GPRS) Tunneling Protocol (GTP). Its primary function is to uniquely identify a specific GTP tunnel between two endpoints. These endpoints are typically a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN) in a mobile network, or between other network elements like the eNodeB and the Mobility Management Entity (MME) in LTE networks.
When data packets are tunneled between these network nodes, the TEID acts as a label or reference