GRE-in-UDP Encapsulation

Investigating the multipath extension of the GRE in UDP technology

“…It is based on the "GRE in UDP Encapsulation", (see Fig. 1), which is currently a "Work in progress" state RFC Draft document [7].…”

“…The purpose of the Network Layer multipath communication is the same as other multipath technologies ( [8,9]): aggregating the capacities of the paths and/or giving redundancy/backup path possibility for the communication. The PDU travelling through the network follows exactly the PDU specification of [7], so using only one path in the MPT architecture will result in the traditional GRE in UDP technology (i.e. the tunnel interface will be mapped statically to a physical interface).…”

“…If the outgoing path is identified, the packet will be encapsulated into a "GRE in UDP" segment and will be sent out on the physical interface of the chosen path. The fields of the GRE header will be set according to the specification of [7]. The simplest GRE header contains 4 octets: 16 bits of zeros and 16 bits of protocol type identification value (i.e.…”

“…The packet receiving mechanism is a little bit simpler. When a packet arrives to the physical interface, the destination UDP port number must be the special "GRE-in-UDP" port number value (it is not yet assigned by IANA, as written in [7]). Then the packet will be read by the MPT software.…”

“…The most important difference is the lack of the GRE in UDP sublayer in the old version (as it was developed as a standard IP in UDP tunneling technology). We included the GRE in UDP sublayer into the model, thus the GRE in UDP header was included into the new PDU (according to [7]). This modification makes it possible to build a new service feature into the MPT environment: the Sequence Number field of the GRE header can be used to guarantee the in order delivery of the packets to the receiver's tunnel interface.…”