SatSig topic:

Unable to Browse from 11pm

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Aug 18^th, 2007 at 1:12am

Hi All,

I am monitoring a cybercafe with a linkstar on PAS1R (intelsat). Everyday from 11pm browsing grinds to a halt, and stays like that till 8am. Please people what could be responsible for this bizzare occurence?

Daniel

Aug 18^th, 2007 at 10:29am

A few ideas ..

1. Tell the hub and discuss. There could be many reasons.

2. Loss of satellite link - one way or the other. This could be due to serious dish mispointing, either your dish or the hub dish. Don't touch anything at your dish for the moment. Observe only. Measure the bit error rate every hour or so over the whole day. How does it change ?. Plot a graph over time. Does it gradually get worse during the evening and improve gradually in the early morning? Is it really bad between 11pm and 8am?. If so, then the satellite may be on the side of the main beam and its small diurnal movement can increase and decrease its level by several dB. Remember the transmit beam is narrower than the receive beam. When pointing you must adjust to the exact centre - adjusting for a just good enough receive signal is quite inadequate.

3. If the bit error rate increases suddenly or the service fails suddenly consider loose F cable connection (fails at low temperature). It is also possible to have LNB or BUC faults that come and go with temperature changes.

4. Interference is a possibility but this needs someone with spectrum analyser to detect. Maybe someone puts up a carrier each night between 11pm and 8am. Is your polarisation well adjusted?.

5. Traffic. During the period when browsing is a problem try to work out if any traffic is getting through. Is some application on the cafe LAN overloading the satellite link?. Does some automated backup software activate itself and try to upload many Gbytes of files to some backup centre somewhere?. Is someone running an automated downloader and receiving excessive data ? Maybe some other site on the same network has such a problem and is blocking everyone - ask the hub to check traffic to/from each site.

Best regards, Eric.

Aug 18^th, 2007 at 12:58pm

Hi Daniel,

How many PCs you have there in your cafe and what VSAT service you are using currently? How much bandwidth you have? Sharing ratio? Do you have any CIR bandwidth included in your service package? Any SLA?

Of course what Eric said should be first things to try, but to me it sounds like you're on a highly oversubscribed service or a service package which is not adequate for your actual traffic demands. Cafes are usually generating extremely intense loads, especially when they get crowded.

Another thought is that if the bandwidth is poorly managed and there are no firewalls, layer 7 filters or similar traffic engineering appliances on your local network, you may easily run into troubles. I strongly encourage every cafe customer of ours to have some sort of bandwidth management solution - either 3rd party like Packeteer or BusinessCom's TES-1000 unit.