Integrated GR-303 Application
The Telcordia GR-303 technical specification?defines the overall system functions and performance levels required when integrating a DLC system into a Class-5 switch. Within this application, the LET bay requires two Tellabs 1000 Data Link Processor (DLP) cards. These provide a redundant Embedded Operations Channel (EOC) and Time slot Management Channel (TMC) for a 64 Kbps datalink to the Tellabs 1000 system. The DLP cards operate in conjunction with a minimum of two T1X-XCVR modules to terminate the GR-303 switch Virtual Interface Group (VIG) up to a maximum of 28 T1X-XCVR modules. The service provider assigns Call Reference Values (CRVs) from the Class-5 switch to POTS lines at the RST. A GR-303 virtual interface group can support up to 2048 CRVs or POTS lines with 2–28 T1s, depending on the desired concentration ratio. The Tellabs 1000 supports up to 3 GR-303 VIGs in one system. The LET to RST transport can be copper or fiber fed.
Current Switch Topologies
Up to this point, we have addressed the Class-5 switch replacement of remote switches into receiving switches. On occasion, however, service providers may need to collapse a?stand-alone Class-5 switch into another stand-alone Class-5 switch or host softswitch. In these situations, service providers must decide whether to:
- Use 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 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.
- Preprovision receiving office translations or develop a Class-5 switch cut script.
Tellabs 1000 MSAP deployment options
Tellabs 1000 MSAP can be used for Class-5 switch replacement. Customers in the collapsing CO receive their dial tone and services from that Class-5 switch; the interoffice 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.
Tellabs 1000 can be used collapsing a Class-5 switch into another Class-5 switch. The new receiving switch now processes all calls, and local copper pairs and cables as well as additional DLCs are consolidated in the Tellabs 1000 LAG bays. If the existing local DLCs are Tellabs 1000s, the service provider can consolidate existing Tellabs 1000 LET bays into the Tellabs 1000 LAG bays to reuse the “now spare” equipment at other locations. If the existing local DLCs are not Tellabs 1000s, the service provider can reterminate those central office terminals into the Tellabs 1000 LAG bays. The Tellabs 1000 LAG now handles call processing within the CO serving area.
Tellabs 1000 can also be used when collapsing a Class-5 switch into a softswitch. This collapse scenario requires the addition of a softswitch with a SIP Mediation gateway. The softswitch functions as an IP gateway, converting the TDM-based GR303 DS1 links from the Tellabs 1000 and transporting them to the softswitch.