On 8/26/07, Jason LeBlanc <jml@packetpimp.org> wrote:
More on point for this thread, I always have new vendors bring in fiber maps and show me their paths. Images of the intended path specified on the map are part of the contract, including verbage regarding failover paths. Once I know where their fiber is, I can look for another vendor that takes a different path.
From a technology standpoint, a lot of carriers are starting to use intelligent optical switches
This often won't get you the most cost-effective connections, and sometimes it'll be bad for performance as well, and doesn't always take advantage of available technology. For instance, if Carrier 1 and Carrier 2 both use the same route for their primary connection, and you buy from Carrier 1 because they're 5% cheaper, you may find that Carrier 2's second-best route is a lot more expensive that Carrier 1's. If you're buying from two carriers to get equipment diversity as well as route diversity, you've lost. Another kind of problem I've run into in the past - here in California, to get from SF to LA, you can either go down the coast or down the Central Valley, depending on which railroads or highways you like. But there's another route that takes a railroad connection from SLO (middle of the coast) to Bakersfield (south/middle of the valley), and if your primary connection uses that route, the options for diverse routes go through Salt Lake City or Denver. Given the history of what fiber got built when, you'll find that for some speeds many of the carriers use that crossover route, while for lower speeds there's a lot more choice. that give them automated provisioning, automatic reroutes, etc., so while they can show you where their cable routes are, and where the most likely provisioning and reroutes go, in general you can't get a precise guaranteed route, because that's not what the switches do.
What I find hard to combat are M&A changing operations over time, In general, it's hard for one carrier to keep track of diversity (though some can), and much much harder for two carriers to keep diverse from each other. And the tracking problems scale differently for large connections, where you may build custom access rings, than for small connections where most providers are reselling telco last-mile copper.
There's also the problem of diversity philosophy - it's not uncommon for large East-Coast companies to view equipment diversity as the critical problem, and concentrate their switches into a smaller number of larger sites where they can do cost-effective sparing, and have their fiber spread out across many different physical routes, not remembering that customers in the West Coast expect that buildings just fall down sometimes, so they care about building diversity, and geographical and demographic considerations mean that there are only a few good routes across the Rockies and along the coasts. (Of course, sometimes this means that the West Coast customers buy from multiple carriers to get building diversity and _still_ get caught when a telco DACS fails :-) .... ---- Thanks; Bill Note that this isn't my regular email account - It's still experimental so far. And Google probably logs and indexes everything you send it.