GTP deployments on a Palo Alto Networks firewall include
When you deploy a firewall for Roaming
security, the firewall inspects traffic that flows between roaming
partner networks. The firewall is deployed between the core network in
the home PLMN and the border gateway that connects to the GRX (GPRX
Roaming Exchange) / IPX (Internet Packet Exchange).
When you configure GTP security for roaming, you should
also configure SCTP security for roaming as described in SCTP Use Cases.