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[[Image:MTP2-OSI model.jpg|thumb|300px|Schematic of the MTP2 layr in the OSI model]]
[[Image:MTP2-OSI model.jpg|thumb|300px|Schematic of the MTP2 layer in the OSI model]]
[[Image:Diagram-mtp2-latyer.jpg|thumb|300px|Schematic of TelcoBridges' implementation of the MTP2 layer]]
[[Image:Diagram-mtp2-latyer.jpg|thumb|300px|Schematic of TelcoBridges' implementation of the MTP2 layer]]
MTP Level 2 (MTP2) provides the data link layer functionality within the OSI model. The MTP2 layer in the [[SS7]] protocol stack defines the functions and procedures of the signaling system for the reliable transfer of signaling messages over an SS7 signaling link. It performs functions such as message sequence validation, error checking and flow control.
MTP Level 2 (MTP2) provides the data link layer functionality within the OSI model. The MTP2 layer in the [[SS7]] protocol stack defines the functions and procedures of the signaling system for the reliable transfer of signaling messages over an SS7 signaling link. It performs functions such as message sequence validation, error checking and flow control.




The MTP2 layer is a service provider to the [[MTP3 Layer|MTP3]] link layer, and at the same time it is a service user of the underlying trunk. Two conceptual illustrations of the MTP2 layer are provided to the right.
The MTP2 layer is a service provider to the [[MTP3 Layer|MTP3]] link layer, and at the same time it is a service user of the underlying trunk. Two conceptual illustrations of the MTP2 layer are provided to the right. The first graphic shows how MTP2 fits into the OSI model. The second shows how it is implemented by TelcoBridges and identifies the most important parameters when configuring an MTP2 layer.




The first shows how MTP2 fits into the OSI model. The second shows how it is implemented by TelcoBridges.
The MTP2 layer is used to create a flow control and buffering mechanism over the [[MTP1 Layer|MTP1 layer]]. The flow control works both ways (toward upper layer and toward remote side) to avoid losing packets because of a lack of buffer, because of a temporary resource outage on the local/remote side (i.e., CPU too busy to process packets) or because of poor MTP Layer 1 transport quality (i.e., physical link errors). Because the MTP2 layer contains the buffering scheme, it allows upper layers to retrieve buffers that were not sent in the event of a MTP1 link failure. The MTP2 layer is also responsible to establish the connection with the peer MTP2 layer upon physical link activation.




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*Processor outage procedure (ITU and ANSI only)
*Processor outage procedure (ITU and ANSI only)
*Realignment on link failure
*Realignment on link failure
*Multiple variants, including ITU 1988 and 1992, ANSI 1988 and 1992, TTC, and NTT
*Multiple variants, including ITU 1988 and 1992, ANSI 1988 and 1992
*Regulates data flow when system's resource utilization reaches configurable thresholds
*Regulates data flow when system's resource utilization reaches configurable thresholds
*Prioritizing of user data messages (TTC and NTT only)
*Retransmission of LSSUs and FISUs (TTC and NTT only)
*Auto link realignment on link failure (TTC and NTT only)




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MTP Level 2 assumes these features are provided by layer 1, but also expects errors to be reported by layer 1 so that it can take any appropriate action.
MTP Level 2 assumes these features are provided by MTP Layer 1, but also expects errors to be reported by layer 1 so that it can take any appropriate action. The MTP Layer 1 functions are implemented by the TMedia hardware platforms.




==TelcoBridges and MTP2 ==
==TelcoBridges and MTP2 ==
TelcoBridges supports MTP2 as part of its SS7 signaling stack. It also provides the following functionality:
TelcoBridges supports MTP2 as part of its SS7 signaling stack. It also provides the following functionality:
*56, 64, n x 64 kbps low-speed links (LSL)
*56, 64, n x 64 kbps low-speed links (LSL). Up to 64 links can be configured per unit and 256 links per system ([[TMG7800]])
*1.5 and 2 Mbps high-speed links (HSL)
*1.5 and 2 Mbps high-speed links (HSL). Up to 2 HSL links can be configured per unit and 8 HSL links per system ([[TMG7800]])
*Supports dynamic link configuration
*Supports dynamic link configuration including the creation and removal of links during live system operation




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*ITU-T, Q.701, Q.703
*ITU-T, Q.701, Q.703
*ANSI T1.111.3
*ANSI T1.111.3
*JT Q.703 (TTC, Japan)
*NTT
*NTT Q.703 (NTT, Japan)
*TTC


== Configuration ==


== Related actions ==
*[[Toolpack:Protocol_Stack_Settings_D#MTP2-MTP3-ISUP|Web Portal v3.0: SS7 Signaling]]
*[[Toolpack:Create an MTP2 Configuration|Create an MTP2 Configuration]]
*[[Toolpack:Protocol_Stack_Settings_C#MTP2-MTP3-ISUP|Web Portal v2.10: SS7 Signaling]]
*[[Toolpack:Create an MTP2 Link|Create an MTP2 Link]]
*[[Toolpack:Protocol_Stack_Settings_B#MTP2-MTP3-ISUP|Web Portal v2.9: SS7 Signaling]]
*[[Toolpack:Status Menus:SS7 MTP2|Verify status of SS7 MTP2 link(s)]]
*[[Toolpack:Protocol_Stack_Settings_A#MTP2-MTP3-ISUP|Web Portal v2.8: SS7 Signaling]]
 
<div class="mw-collapsible mw-collapsed" data-collapsetext="other versions" data-expandtext="Click here for other versions" style="width: 400px;">
*[[Web_Portal_Tutorial_Guide_v2.7#SS7_ISUP|Web Portal v2.7: SS7 Signaling]]
*[[Web_Portal_Tutorial_Guide_v2.6#SS7_ISUP|Web Portal v2.6: SS7 Signaling]]
*[[Web_Portal_Tutorial_Guide_v2.5#Configuring_SS7|Web Portal v2.5: SS7 Signaling]]
*[[Web_Portal_Tutorial_Guide_v2.4#SS7_Signaling|Web Portal v2.4: SS7 Signaling]]
*[[Web_Portal_Tutorial_Guide_v2.3#SS7_Signaling|Web Portal v2.3: SS7 Signaling]]
*[[Web_Portal_Tutorial_Guide_v2.2#SS7_Signaling|Web Portal v2.2: SS7 Signaling]]
</div>


== References ==
== References ==
*[http://en.wikipedia.org/wiki/Message_Transfer_Part Wikipedia article]
*[http://en.wikipedia.org/wiki/Message_Transfer_Part Wikipedia article]
*[[MTP2:Specification|Supported MTP2 standards and variants]]
*[[MTP2:Specification|Supported MTP2 standards and variants]]
*[[MTP2:Architecture|MTP2 Architecture]]
*[[MTP2:States|MTP2 States]]
*[[MTP2:Statistics|MTP2 Statistics]]




[[Category:Glossary]]
[[Category:Glossary]]
[[Category:Revise on Major]]

Revision as of 09:53, 22 March 2018

Schematic of the MTP2 layer in the OSI model
Schematic of TelcoBridges' implementation of the MTP2 layer

MTP Level 2 (MTP2) provides the data link layer functionality within the OSI model. The MTP2 layer in the SS7 protocol stack defines the functions and procedures of the signaling system for the reliable transfer of signaling messages over an SS7 signaling link. It performs functions such as message sequence validation, error checking and flow control.


The MTP2 layer is a service provider to the MTP3 link layer, and at the same time it is a service user of the underlying trunk. Two conceptual illustrations of the MTP2 layer are provided to the right. The first graphic shows how MTP2 fits into the OSI model. The second shows how it is implemented by TelcoBridges and identifies the most important parameters when configuring an MTP2 layer.


The MTP2 layer is used to create a flow control and buffering mechanism over the MTP1 layer. The flow control works both ways (toward upper layer and toward remote side) to avoid losing packets because of a lack of buffer, because of a temporary resource outage on the local/remote side (i.e., CPU too busy to process packets) or because of poor MTP Layer 1 transport quality (i.e., physical link errors). Because the MTP2 layer contains the buffering scheme, it allows upper layers to retrieve buffers that were not sent in the event of a MTP1 link failure. The MTP2 layer is also responsible to establish the connection with the peer MTP2 layer upon physical link activation.


Features

MTP Level 2 provides the following basic features:

  • Establish and release data link connections
  • Transfer data
  • Normal alignment procedure (ITU and ANSI only)
  • Emergency alignment procedure
  • Signal unit error rate monitor
  • Alignment error rate monitor
  • Basic error correction method
  • Preventive cyclic retransmission error correction method (ITU and ANSI only)
  • Congestion control and congestion abatement
  • Inform MTP Level 3 on detection of error
  • Message retrieval for changeover
  • Processor outage procedure (ITU and ANSI only)
  • Realignment on link failure
  • Multiple variants, including ITU 1988 and 1992, ANSI 1988 and 1992
  • Regulates data flow when system's resource utilization reaches configurable thresholds


MTP Level 2 does not directly provide the following features:

  • Signal unit delimitation, alignment, and error detection
  • Retransmission of FISU and LSSUs (ITU and ANSI only)


MTP Level 2 assumes these features are provided by MTP Layer 1, but also expects errors to be reported by layer 1 so that it can take any appropriate action. The MTP Layer 1 functions are implemented by the TMedia hardware platforms.


TelcoBridges and MTP2

TelcoBridges supports MTP2 as part of its SS7 signaling stack. It also provides the following functionality:

  • 56, 64, n x 64 kbps low-speed links (LSL). Up to 64 links can be configured per unit and 256 links per system (TMG7800)
  • 1.5 and 2 Mbps high-speed links (HSL). Up to 2 HSL links can be configured per unit and 8 HSL links per system (TMG7800)
  • Supports dynamic link configuration including the creation and removal of links during live system operation


Supported MTP2 variants

  • ITU-T, Q.701, Q.703
  • ANSI T1.111.3
  • NTT
  • TTC

Configuration

References