Configuring MTP2

The MTP2 links are the classic way of interconnecting SS7 over TDM.
MTP2 configurations depends both on the local TDM card and on the remote side requirements.

Implementation

MTP2 implementation in YATE is located in ysig library. The methods declaration is in libs/ysig/yatesig.h and the implementation in libs/ysig/layer2.cpp. Class name is SS7MTP2.

Example

Follow this guide to install sangoma cards under Linux.

The MTP2 link is created on demand. To define a MTP2 link you must define the MTP3 linkset that uses it.

In ysigchan.conf:

[mtp3]
type=ss7-mtp3
netind2pctype=ITU
netindicator=national
local=ITU,0-0-6
adjacent=ITU,0-0-5
link=mtp2

[mtp2]
type=ss7-mtp2
autostart=yes
emergency=yes
autoemergency=yes
sig=wanpipe1
filllink=no

Note: According to standards filllink should be 'yes'. We usually set it to 'no' because most of the times the underlying layers don't have support for it (unless when support was added in the hardware and then it's ok to configure filllink='yes').

In wpcard.conf

[wanpipe1]
type=E1
siggroup=w1g1
voicegroup=w1g2

Configuration

From sample ysigchan.conf file:

; Example of a SS7 MTP2 link
;[link1]
; type: keyword: Specify the link type
; Allowed values:
;  ss7-mtp2:      SS7 Message Transfer Part - Layer 2
;type=ss7-mtp2

; autostart: bool: Automatically try to align the MTP2 at startup or on failure
; This should be enabled (default) for normal operation
;autostart=yes

; emergency: boolean: Emergency align SS7 MTP2 layer at startup
;emergency=yes

; autoemergency: boolean: Emergency align link if owner linkset is down
;autoemergency=yes

; filllink: boolean: Configure MTP2 to request link fill (packet repeat) when
;  sending FISU or LSSU packets
;filllink=yes

; maxerrors: int: Number of consecutive errors that cause realignment
; This parameter is constrained between 8 and 256
; When in proving interval this setting is ignored and realignment occurs at
;  4 errors in normal proving or 1 error in emergency proving
;maxerrors=64

; rxunderrun: int: Maximum interval in ms between two packets before we report
;  an underrun condition, zero to disable or 25+
;rxunderrun=0

; layer2dump: string: Filename to dump MTP2 packets to
;layer2dump=

Control

MTP2 Control commands:

Pause	control MTP2_NAME pause	Pause this link message delivery
Resume	control MTP2_NAME resume	Align this link if it is not already aligned and it can auto start
Align	control MTP2_NAME align	Force this to start Align algorithm