SCTP association between multi-homed endpoints over NAT using NSLP

Extended abstract. Network address translation poses a challenge for hosts that attempt to use protocols that place internet protocol addressing information inside IP payload. The same issue exists for the Stream Control Transmission Protocol and is even more difficult when SCTP associations are multi-homed. This paper deals with the options available for establishment of an SCTP association between multi-homed endpoints with multi-point NAT traversal on both sides and stress imposed limitations, when a single-point NAT traversal is used instead. We will discuss a unique problem that SCTP introduce with multi-homing, which is port preservation over an entire SCTP association even if it traverses multiple NATs. Most of the existing traversal techniques do not cover synchronizing multiple NATs and are therefore inappropriate for SCTP. Finally, we will show how the NAT/Firewall NSIS Signaling Layer Protocol can be used for reserving the port number, acquiring public addresses and opening data flows over NATs that are included in the SCTP association.