S1 signalling
bearer provides the following functions:
·
Provision of reliable transfer of
S1-AP message over S1-MME interface.
·
Provision of networking and routeing
function
·
Provision of redundancy in the
signalling network
·
Support for flow control and
congestion control
L2 - Data link
layer
Support of any
suitable data link layer protocol, e.g. PPP, Ethernet
IP layer
·
The eNB and MME support IPv6 and/or
IPv4
·
The IP layer of S1-MME only supports
point-to-point transmission for delivering S1-AP message.
·
The eNB and MME support the Diffserv
Code Point marking
Transport layer
SCTP is supported
as the transport layer of S1-MME signalling bearer.
·
SCTP refers to the Stream Control
Transmission Protocol developed by the Sigtran working group of the IETF for
the purpose of transporting various signalling protocols over IP network.
·
There is only one SCTP association
established between one MME and eNB pair.
·
The eNB establishes the SCTP
association. The SCTP Destination Port number value assigned by IANA to be used
for S1AP is 36412.
Protocol
specification
3GPP TS 36.410 -
Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 layer 1
general aspects and principles
3GPP TS 36.411 -
Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 layer 1
3GPP TS 36.412 -
Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 signalling transport
IETF RFC 2460:
"Internet Protocol, Version 6 (IPv6) Specification"
IETF RFC 791 (September,1981):
"Internet Protocol"
IETF RFC 2474 (December
1998): "Definition of the Differentiated Services Field (DS Field) in the
IPv4 and IPv6 Headers"