AssociatedSignallingModeintheM-MGw(M3UAAgen

Slide titleIn CAPITALS

50 pt

Slide subtitle 32 pt

Associated Signalling Mode in the M-MGw

(also called “M3UA Agent”)

By Cade Bull (update from Aziz Zine’s presentation)

Top right corner for field-mark, customer or partner logotypes. See Best practice for example.

Slide title 40 pt


Text 24 pt

Bullets level 2-520 pt

OPER/MUANZA-07:003978 Uen Rev PB1 Ericsson Internal Associated Signalling Mode in the M-MGw (M3UA Agent) 2007-11-272

Agenda

Understanding M3UA Agent How SS7 Works Alternatives to M3UA Agent Why is M3UA Agent Needed? How Does M3UA Agent Work? M3UA Agent Implementation M3UA Agent Feature Information Additional Material/Presentations


Slide title 40 pt


Text 24 pt



Understanding M3UA Agent

To be able to understand what M3UA Agent is and how it works, you must first understand how SS7 Signalling Maintenance Messages work and in what circumstances such a feature is required.

The first thing to note, is that SS7 Maintenance Messages are not STP’d, i.e. they are only between 2 nodes, i.e. Below Signalling Link Test Messages (SLTM) from BSC1 will only be sent to MGw1 and SLTM’s from MGw1 will be sent to both BSC1 and MSC1

BSC1 MGW1 MSC1


Slide title 40 pt


Text 24 pt



How SS7 Works

When an SS7 link is initialling activated, both sides of the SS7 link need to ensure the signalling link is working and configured correctly on both sides. In order to do this a Signalling Link Test Message (SLTM) and a Signalling Link Test Acknowledge (SLTA) is sent.The information in the MTP Header is: Originating Point Code (OPC) Destination Point Code (DPC) Signalling Link Code Test Pattern


Slide title 40 pt


Text 24 pt



How SS7 Works

In the previous diagram, when MGw1 receives a SLTM from BSC1, it checks the following: Is the DPC my Point Code? Is the OPC the Point Code I think the BSC1 should be? Is the SLC the same SLC I have defined

If any of the above checks are not correct, then MGw1 will not send any response.If however the checks are all successful, then MGw1 will send a SLTA back to BSC1 and parse back the original Test Pattern (this ensures no corruption). MGw1 will then send its own SLTM to BSC1 and expect a SLTA in response.


Slide title 40 pt


Text 24 pt



How SS7 Works

If no SLTA is received after sending a SLTM, then a timer expires and the signalling link remains disabled. A good indication of one of these values being incorrect are when the NniSaalTp MO counters pmNoOfAlignmentFailures & pmNoOfAllSLFailures are not increasing but the Mtp3bSlxxx MO counter pmNoOfAALOUTInd increases, which indicates that no SLTA was received for a SLTM.


Slide title 40 pt


Text 24 pt



How SS7 Works

The following are examples of SLTM and SLTA messages:Originating Point Code (OPC): 2601Destination Point Code (DPC): 2610Network Indicator: 3-Reserved for national useSpare Bits (Message Priority): 0Signalling Link Selection (or SLC): 0 Signalling Link CodeService Indicator: Signalling network testing and maintenance messageMessage: Signalling Link Test Message (SLTM)Test Pattern Length (No. of octets): 15 Signalling Link Test messageHEX DATA1D 00 00 16 00 C1 32 4A 8A 02 11 F0 AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA

Originating Point Code (OPC): 2610Destination Point Code (DPC): 2601Network Indicator: 3-Reserved for national useSpare Bits (Message Priority): 3Signalling Link Selection (or SLC): 0 Signalling Link CodeService Indicator: Signalling network testing and maintenance messageMessage: Signalling Link Test Acknowledge (SLTA) Signalling Link Test AcknowledgeTest Pattern Length (No. of octets): 15HEX DATA23 00 00 16 00 F1 29 8A 8C 02 21 F0 AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA


Slide title 40 pt


Text 24 pt



Alternatives to M3UA Agent

There are 2 alternatives to using M3UA Agent, which are essentially the same, however they are implemented slightly different.

Direct E1 ConnectionThe BSC could have a direct E1 connection to the MSC, therefore allowing direct signalling.

BSC MGW1 MSC


Slide title 40 pt


Text 24 pt



Alternatives to M3UA Agent

Circuit EmulationCircuit Emulation allows the M-MGw to put E1’s over ATM and with the use of 2 Circuit Emulation configurations (Aal1TpVccTp MO) it essentially performs E1 Cross ConnectionsNOTE: From R4.1 TDM Cross Connections are available, however since Associated Signalling Mode is also available, TDM Cross Connections are not the best option.

BSC MGW1 MSC

ATM

E1 E1

Circuit Emulation Solution

BSC MGW1 MSC

E1 E1

TDM Cross Connect Solution


Slide title 40 pt


Text 24 pt



Why is M3UA Agent Needed?

According to the 3GPP specifications, telecommunication equipment should support quasi-associated signalling, which essentially means it can use an STP to signal to a node, i.e. The BSC should be able to signal to the MSC via the MGw/SGw.

BSSAP/SCCP/ MTP3/MTP2/MTP1

BSSAP/SCCP/ M3UA/SCTP/IP/LL

MSC-S

MGw/ SGw

BSC

TDM

IP

Signalling link Physical link


Slide title 40 pt


Text 24 pt




Some BSC/RNC suppliers either do not follow the 3GPP specifications or are legacy products, i.e. BSC and as such, their BSC’s/RNC’s must signal directly to the MSC.Now the problem with this is that as seen before if the BSC has the MSC’s DPC in the SLTM, then the M-MGw will ignore the SLTM as it is not the M-MGw’s OWN SP and as a result the signalling links will never come up.If the BSC specified the MGw’s DPC in the SLTM, then the signalling links would come up, however SCCP would not work since the M-MGw would terminated the SCCP message, rather than the MSC.


Slide title 40 pt


Text 24 pt




The permanent solution is to allow the MGw to accept Maintenance Messages, which are meant for the MSC and to reply to these messages.The only alternative besides M3UA Agent is to have an E1 signalling link directly connected to the MSC either by using a MUX, using TDM Cross Connects (supported in R4.2 onwards) or by using Circuit Emulation in the M-MGw. The main disadvantages of this is: Additional Hardware is required in the M-MGw With Circuit Emulation additional ETM4 boards are required Signalling is no longer central Only 1 ETMC1 board is provide with GMPv3


Slide title 40 pt


Text 24 pt



How Does M3UA Agent Work?

The way M3UA Agent works is that once configured, the M-MGw will be aware of both the BSC/RNC Point Codes that need to be “tricked” and the MSC’s Point Code, which is normally meant to receive the Maintenance Messages.From the BSC side, it should be configured as if it were directly connected to the MSC.When the BSC sends a SLTM to the M-MGw, the M-MGw will check the link is ok and the DPC in the message matches the MSC. It will then send back a SLTA message using the BSC’s DPC as the DPC and the MSC’s DPC as the OPC. The BSC will then think that the MSC responded and bring the links up. The M-MGw will also initiate a SLTM.


Slide title 40 pt


Text 24 pt



How Does M3UA Agent Work?

With the M-MGw now being able to terminate the maintenance messages from a node that does not support quasi-associated signalling, the M-MGw can now route all the protocol message as it normally would.eg, without this feature, the M-MGw would receive an SCCP message from the BSC, which contained the MSC’s DPC. The M-MGw would then send that message to the MSC. The MSC would also send SCCP messages to the MGw with the BSC’s DPC and the M-MGw would route these messages to the BSC.With this feature the above mechanism is still valid as all messages coming from the MSC have the correct OPC.


Slide title 40 pt


Text 24 pt



M3UA Agent Implementation

In order to implement M3UA Agent, the following needs to be configured: A new Mtp3bSp in the M-MGw for the M3UA links towards the MSC and SgwMgmtMapping MO’s to be created on. NOTE: useSgwMgmtMapping must be set to TRUE in the Mtp3bSp SgwMgmtMapping MO’s for each BSC/RNCNOTE: The Mtp3bSp defined in the first point should not have any additional configuration defined, only the links to the MSC and BSC, i.e. The VMGw should still be configured on the normal Mtp3bSp as the new Mtp3bSp is hidden from the rest of the network.


Slide title 40 pt


Text 24 pt



M3UA Agent Implementation

WARNINGWhen implementing M3UA Agent, you need to ensure that you do not implement mapping towards the MSC as the Sigtran link between the MSC and MGw has crashed due to this miss-configuration, i.e. Ensure that the MSC is never specified as the Originating Point Code in the configuration.

Also Note that due to additional Sigtran links required between the MSC and M-MGw, additional IP address’s may be required in the MSC, existing SCTP end points can be used in the M-MGw


Slide title 40 pt


Text 24 pt



M3UA Agent Implementation - EMAS


Slide title 40 pt


Text 24 pt



M3UA Agent Implementation - EMAS


Slide title 40 pt


Text 24 pt



M3UA Agent Implementation - MO

The following MO Script can be used to create a MAPPING for the BSC:ECHO "SgwMgmtMapping SgwMapping_y-xxxx_a-bbbb"CREATE( parent "ManagedElement=1,TransportNetwork=1,Mtp3bSpItu=d-gggg" identity "SgwMapping__y-xxxx_a-bbbb" moType SgwMgmtMapping exception none nrOfAttributes 3 destPointCode Integer bbbb SP for MSC origPointCode Integer xxxx SP for BSC (Never specify MSC DPC here) userLabel String "SP Mapping between__y-xxxx_a-bbbb“)

NOTE: Only one mapping per BSC is required, no mapping for the MSC is required.

Example Signalling MO

Example SgwMgmtMapping


Slide title 40 pt


Text 24 pt



M3UA Agent Feature Information

M3UA Agent feature official FOA site: China M3UA Agent feature number: FAJ 121 0091 M3UA Agent feature key: CXC4010071/3032 M3UA Agent Supported From: R4.1 Additional Information: R4 Feature Description

NOTE: Although this feature is available in R4.1, it is recommended to use the latest software as there are some important fixes in R4.1.2.0 and R4.2.2.2, which prevents crashes and database corruption

http://gask2web.ericsson.se/pub/get?DocNo=22104-FGC101808


Slide title 40 pt


Text 24 pt



Additional Material/Presentations

Additional presentations are available via KnowledgeBase

Direct links to material in KS Tool:Migration Guide to Associated Signalling Mode in M-MGw R4Associated Signaling Mode in SignalingAssociated Signaling Mode in SGw

https://knowledgebase.internal.ericsson.com/Pages/Default.aspx

https://knowledgebase.internal.ericsson.com/MGw%20and%20MSC%20SW%20Deployment%20and%20Support/Lists/KO/DispForm.aspx?ID=253

https://knowledgebase.internal.ericsson.com/MGw%20and%20MSC%20SW%20Deployment%20and%20Support/Lists/KO/DispForm.aspx?ID=3

https://knowledgebase.internal.ericsson.com/MGw%20and%20MSC%20SW%20Deployment%20and%20Support/Lists/Forum/DispForm.aspx?ID=516





Slide title 40 pt


Text 24 pt



Date post:	11-Feb-2016
Category:	Documents
Upload:	abhinav-garg
View:	2 times
Download:	0 times

AssociatedSignallingModeintheM-MGw(M3UAAgen

Documents