whilst studying for CCNA, I come across a lot of reference to ISDN being a good backup technology. I know this might sound like a stupid question, but, what is used mostly in WAN environments.? Over here, in Tokyo, I get told that Frame Relay is not used that much, as opposed to ISDN. What do you guys see most in your environments.? Cheers.
AFAIK, frame relay is a service offered by most ISP's in Japan, and also quite heavily used (check the link below). It is usually much cheaper than ISDN, and therefore often the primary method of connectivity. Over here in Europe, ISDN is available almost everywhere, while, AFAIR, it is not that heavily used in the US...
It horses for courses really, and here we are talking two rather different breeds of horses.
ISDN is a dialup technology, and it usually charged by the minute. This makes it very suitable for a backup connection, or for a link that is used on an occasional basis. The abonnement costs are usually quite low compared with the per-minute costs. Here in Luxembourg it is one of the standard domestic telephone services on offer - I have it at home. It has the flexibility that once you have an ISDN line you can use it to dial any other ISDN line - or even to a modem line if you have a modem integrated in your router - or just use it as a telephone line.
Frame Relay, on the other hand, is an "always on" service. It is set up as PVCs, so your endpoints have to be agreed in advance with your provider. Generally you only pay an abonnement cost for the PVC, and no incremental costs per minute or per data volume.
The pricing structures are different in each country, so would have to do your own calculations based on your traffic expectations. I did a study here comparing a local leased 64 kbps line against an ISDN dialup. I found that the ISDN was cheaper if it was open less than 24 hours per month, but got very expensive if it was heavily used.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.