ISE Magazine, August 2018

ISE ICT SOLUTIONS EDUCATION104CLASS 5 SWITCH the host CO via Add Drop Multiplexers ADM and integrated interfaces either GR 008 or GR 303 Figures 1 and 2 illustrate the collapse of a remote switch into a Class 5 switch with the NGDLC taking over the function of the collapsed switch The Numbering Plan Area NPA NNX Exchange or Central Office code which is derived from the host office remains unchanged All emergency stand alone features remain within the host switch The key to this entire solution is that the NGDLC should support Universal GR 057 and integrated GR 008 and GR 303 switch interfaces Universal GR 057 Telcordias GR 057 is used if there are no digital switch interfaces available at the receiving Class 5 shown in Figure 2 This application extends the Class 5 switchs analog line unit termination to the outside plant thereby eliminating direct copper pairs and moving closer to the customers premises The Class 5 switch replacement application calls for the deployment of a NGDLC LET in the receiving CO and the NGDLC RST in the collapsing CO If the objective is to eliminate the collapsing building the service provider can deploy the RST in a Controlled Environmental Vault CEV hut or cabinet separate from the CO building Integrated GR 008 Telcordias GR 008 technical specification defines the overall system functions and performance levels required when integrating a DLC system into a Class 5 switch The GR 008 compliant integrated access interface allows the NGDLC system to consolidate DS0s into T1 spans coming from a local digital switch GR 008 supports POTS Pay Coin and universal voice grade UVG circuits Mode1 GR 008 supports up to 96 DS0s into 4 T1s Mode2 GR 008 supports up to 96 DS0s into 2 T1s Integrated GR 303 Telcordias GR 303 technical specification defines the overall system functions and performance levels required when integrating a DLC system into a Class 5 switch The GR 303 compliant integrated access interface allows the NGDLC system to concentrate up to 2048 DS0s into 2 to 28 T1 spans coming from a local digital switch Switch Topologies On occasion service providers may need to collapse a stand alone Class 5 switch into another stand alone Class 5 switch or a host softswitch In these situations service providers must decide whether to Use Local Number Portability LNP until full cutover of the collapsed switch which could require add and disconnect service orders for each working line in each switch Rehome the NPA NNX code to the receiving switch prior to cutover which could require additional trunking back to the collapsed switch until after the cutover Use a flash cut or a roll cut re provision receiving office translations or develop a Class 5 switch cut script Figure 3 shows a typical CO prior to a Class 5 to Class 5 switch replacement Customers in the collapsing CO receive their dial tone and services from that Class 5 switch the Inter Office Facilities IOF trunks between the COs route their calls to other end offices The local Class 5 switch handles call processing within this CO serving area Figure 4 Result of collapsing a Class 5 switch into another Class 5 switch Figure 5 Result of collapsing a Class 5 switch into a softswitch