I can always find a good read from Ivan!

“If you’re serious about the high-availability of your network, your remote sites have a primary and a backup link into the core network. In the old days, the backup link was usage-charged (think about ISDN and X.25), and the important issue was to reduce the usage of the backup link. These days, we usually use fixed-cost primary and backup links (for example, Metro Ethernet for primary link and Frame Relay or ADSL for the backup), and once the top managers realize that, they want us to utilize both links all the time.

It doesn’t take much to convince anyone (even people who have never been involved in networking) that it doesn’t make sense to load-share between a 20 Mbps symmetrical fiber-optic link and a 1Mbps/256 kbps asymmetrical ADSL link. The next idea the managers get is usually very predictable: why don’t you transport certain applications over the backup link? Welcome to the murky world of policy routing.”

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