I am using lan extenders and extending Intranet up to a distance of 6 km. However the link is not reliable and sync alarm glows in between.I would like to know how can I enhance the efficiency of this link.

Adhish

Just to make sure I've got my terminology correct, you are using a LAN extender, which connects different parts of a LAN together through a WAN? If that's the case, then it is the integrity of your WAN that you need to investigate. Whose network are you transmitting the signals over?

If you are using LAN <i>repeaters</i>, these are designed to boost the signal of LAN runs. They are simple powered devices that take the incoming signal, and rebroadcast it along. You need these because there is a signal degradation for each metre of CAT5, fibre optic, or taut string that you're using to connect your LAN. If you exceed a certain distance, the degraded signal needs to be cleaned up and have its power boosted. If this is the case, then I would suggest moving to a fibre optic link, which will have a much lower attenuation over the 6km.