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The Requirements of the redundant configuration between MGCF and MGF. Version 1.0 Date : 2006/04/05. Table of contents. Purpose of the proposal Introduction to MGCF and MGF MGC and MG in Practice Networks and element failure The requirements Policy between MGCF and MGF
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The Requirements of the redundant configuration between MGCF and MGF Version 1.0 Date:2006/04/05
Table of contents • Purpose of the proposal • Introduction to MGCF and MGF • MGC and MG in Practice • Networks and element failure • The requirements • Policy between MGCF and MGF • Policy between MGCF and MGCF • Policy between MGCF and SGF
Purpose of the proposal • NGN is the Next Generation Public Telecommunication Net. • It is important to avoid a single point of failure in Public Telecommunication Net. • This can typically be achieved through the use of redundant equipment elements. • There is much difference between the use of redundant configuration in NGN and in traditional PSTN. • The use of redundant elements is in practice, but the policy of the redundancy model has many problems which remain further study.
Introduction to MGCF and MGF • In NGN IMS and PES, MGCF and MGF are used to inter-work with PSTN/ISDN. • In practice,the equipment elementes of MGCF and MGF are set up at the roll lay. The scale is large. • It is necessary to study the requirments of the redundant configuration between MGCF and MGF.
MGC1 MGC2 SG Mn Le Le T-MG1 T-MG2 PSTN/ISDN Area A Area B MGC and MG in Practice
MGC and MG in Practice • In the normal condition, MG1 is controlled by MGC1 and MG2 is controlled by MGC2. MGC1 and MGC2 deal with inter-working with PSTN area A and B separately. • The signalling inter-working with PSTN is implemented through SG。 • As MGC1 is failure, MG1 turns to register with MGC2. And when the register is accpepted, the inter-working with PSTN through MG1 is controlled by MGC2. • At MG1, the failure of MGC1 has an analogue to the networks failure between MGC1 and MG1. And at MGC2 the failure is similar to the networks failure between MGC1 and MGC2. • Therefore there are 3 kinds of failure should be considered in practice. They are showed in the following chart and marked by “╳ ”.
MGC1 MGC2 SG Mn Le Le PSTN/ISDN T-MG1 T-MG2 Networks and element failure
MGC1 MGC2 SG Mn Le T-MG11 T-MG2 T-MG12 PSTN/ISDN Area A Area B Networks and element failure • In actual practice, every MGC always controls more than one MGs. And the exchanges in PSTN inter-work with MGC through more than one MGs. The above chart should be modified as the following.
The requirements • After MG succeeded registering with a new MGC because of the failure of the old MGC or the networks, the inter-working with PSTN through the MG must be successful. • During the MG’s switching and after its successfully re-registering, it should not take place that an amount of trunks between MG and PSTN are blocked. • The process of one MG’s re-registering should not influence on the other MGs, including those controlled by the old MGC and those by the new MGC. • The failure of MGC and the switching of MG must be harmless to the existed bill. • How to deal with the existed call connection after MG re-registered, remove or remain? • Is the process of MG’s switching controlled by MGCs automatically according to the prearranged policy, or the process needs additional networks elements participating in or manual operation?
Policy between MGCF and MGF • In practice, H.248 is used between MGCF and T-MGF. • More than one MGCs can be prearranged in MGF by configuration management function. As MG detects losing connection to the current control MGC, the registering with the next MGC will take place. • In common, the existed call connection in MG will be removed when MG detects losing connection to MGC. The requirements and policy remains further study.
Policy between MGCF and MGCF • MGCFs use “heartbeat” message to detect the working state of peer nodes. MGCF also exchange the state of MGs, the state of the terminals in MGs and so on. • How MGCs exchanges the information remains further study.
Policy between MGCF and SGF • In practice, Sigtran is used between MGCF and SGF. • The signalling association between SGF and MGCF is always created in spite of MGCF is master or not. And only the master MGCF can active the association. • When MGC detects MG unregistered, it will deactive the assocaition. On the contrary, it will active the assocaition when MGC detects MG registered. The procedure is SIGTRAN ASPM procedure. But, in redundancy model, the sequence of the procedure remains further study.