Cisco Certified ExpertForeign Exchange FX
To deploy BRI circuits to customer sites, the service provider's switch must be able to accommodate the ISDN equipment. This typically includes a fairly large switch such as a Lucent 5ESS or Nortel DMS-100, with adequate port density and a series of line cards both at the CO and IDLCs. When deployed in IDLCs, BRI service typically takes up three full DS0s, so available bandwidth is also a factor. In areas that can't support these requirements, an FX of the circuit might be necessary. At its most basic level, an FX circuit reroutes the local loop through a switch at a CO that does not provide local ISDN service. Figure 8-24 shows a basic depiction of an ISDN circuit that is foreign exchanged to a remote office.
In Figure 8-24, the FX ISDN service is deployed through a switch that does not necessarily provide local exchange service. In some areas, the facilities required are just not available. Rather than upgrade an entire switch for a couple of ISDN customers, the service provider would rather redirect you to a switch or IDLC that is already providing such service.
FX circuits are normally handled by a group called special services. They are typically a separate entity, which means that to test or repair this type of circuit you probably need to go through them directly.
There are cases where FX is not possible due to location or distance from the CO (if you live in the boonies). If this is the case, you might not be able to obtain ISDN service.
Figure 8-24 Foreign Exchanged BRI Circuits
Foreign Exchange Switch Providing ISDN Service
Figure 8-24 Foreign Exchanged BRI Circuits
Foreign Exchange Switch Providing ISDN Service
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