Derbyshire Constabulary: Case Study
When Derbyshire police wanted to connect their local area networks and PBXs they looked at 2Mbps services and realised it was going to be an expensive exercise.Most of the buildings to be connected were within a few miles of each other. Derbyshire’s Peter Mitchell, never one to be afraid of new technology, thought DSL might provide the answer to how to connect the sites at high speed without breaking the budget.
After reviewing a number of DSL products, it soon became apparent that the majority only provided IP bridging, but none seemed to offer IP bridging, support for third party devices and PBX-to-PBX connectivity.Derbyshire had long been using Case Communications’ 2Mbps voice and data products. Peter decided to contact Case Communications to see what they might have to offer.
Leading the way with broadband
XLR 4600 – 4.6Mbps Triple Service Broadband
Case Communications manufacture a G.SHDSL product called the XLR 4600, which is capable of operating at 2.3Mbps over a 2-wire copper circuit (BT EPS 9) and at 4.6Mbps over a 4-wire copper circuit (EPS 8). More importantly the Case XLR 4600 supports three services at once:
- IP LAN traffic via an internal filter bridge
- PBX traffic via an internal E1 G.703 port
- Third party devices transparently via an X.21 port.
Peter arranged to borrow a pair of Case XLRs to test. But things did not go as smoothly as they should, as the PBXs did not provide CRC 4 checking. This meant they had problems running over the E1 trunk.After discussions with Case, the Case developers made changes to the XLR software, and provided a menu option to either check the CRC or to ignore it, something possible with a UK manufacturer.
After the changes the PBXs were up and running at a full 2 Mbps, leaving Derbyshire with another 2.6Mbps of bandwidth available for other services.
As Peter explained: “It’s vital to test DSL products before you purchase, as copper circuits vary. Case had enough confidence in their XLRs to let us try them, and we found they worked on circuits on which other vendors’ products had previously failed to work.”