Michael, On Fri, 21 Jun 1996, Michael Dillon wrote: ...
But to me, backhoes are the most interesting failure mode. For one,I don't think that backhoe problems can be eliminated
I don't know about total elimination but we're working on it. Sprint is currently deploying 4-fiber bi-directional SONET rings that will cause fiber cuts to go virtually unnoticed. Circuits are switched to a protect channel in about 50 msec after a failure of the primary path. and I think that as
the physical mesh of fibre becomes more finely divided over the geography, these incidents will increase. And I also don't know of anyone taking action to protect against these events by building geographic redundancy into their backbones. This may be partly because NSP's often don't have any idea where the fibres lie and partly because they want to use a specific infrastructure like SPRINT and its railway rights of way. The incident in the Northeast where a backhoe cut a Wiltel(?) fibre bundle that was carrying critical DS3's leased by all the NSP's in the region points out how catastrophic this can be.
Again, this may not be totally eliminated. However, we are working to provide as much physical path diversity as possible. Jim Steinhardt SprintLink Engineering
Michael Dillon ISP & Internet Consulting Memra Software Inc. Fax: +1-604-546-3049 http://www.memra.com E-mail: michael@memra.com