Standards for Technology in Automotive Retail
No communications method is perfect. Despite promises made in carrier SLA, connections will go down occasionally. Remedies under SLA’s only include fees paid for inoperative circuits. Larger sums of money may be at stake in the form of lost business if the connection is down for an extended time. While most connection outages are very short in duration, a backup for that connection is still a requirement. This backup should be a dialed connection attached to the router. The router should have the intelligence to sense that the primary line is down and automatically activate the backup line. In most cases, the dealership users will not even realize this has happened. Once the router sees the primary circuit working again, it will drop the dialed connection. Care should be taken when setting the router‘s sensitivity to circuit outages. Connections can drop for a few seconds quite frequently. If the router is too quick, it will dial a new connection when one is not necessary. Each dialed connection increases the backup cost. Likewise, connections being reestablished often come up briefly, go back down, and then come up for good later. If the router is too quick to drop the dialed connection, it will only have to redial the connection right away.
For smaller dealerships whose total bandwidth is not much more than the minimum 128Kbps, a dialed backup providing 56Kbps is sufficient. Dialed connections with lesser bandwidth may work but performance will be noticeably downgraded. Larger dealers that require primary connections well above the 128Kbps minimum may need to explore the use of ISDN, DSL, or dialed backup connections. The greater the bandwidth on the primary connection, the greater the backup bandwidth should be. Again, the dialed connections will work, but the lower capacity is noticeable to users and it will affect their productivity. It is quite common to see installations with dedicated or frame relay service using ISDN backups instead of standard dialed connections. Backup communication connections should be checked at least monthly. Nothing is more frustrating to systems administrators than having their backup plans fail. The whole goal of the backup connection is to function in a crisis. When it does not, the dealership loses productivity and the system administrator looks foolish. This backup configuration can be tested by simply disconnecting the primary connection. Within the set time the router should open the backup connection. Once that has been completed, reconnect the primary connection, and the router should drop the backup connection again after the set time.
In worst-case scenarios, it would be wise to keep a dial-up account that can be used from a single PC in the event that access from the LAN cannot be made through the router. This would be caused by the failure of the primary and the backup connections or, more likely, a hardware failure by the router. This secondary backup method will not perform very well, and it cannot service every dealership user at the same time. However, it will serve well enough to transfer parts orders before the shipping deadline, or car orders before the allocation closes.