From: Larson, Chris (Contractor) (Chris.Larson@xxxxxx)
Date: Wed Nov 14 2001 - 14:02:01 GMT-3
We are doing that here right now. We are doing just what you mentioned. We
are purchasing 2 of everything for our hot backup site. We have 2 7206 VXR's
with an OC-3 to each. Both are in area 0 and connect to 2 7206's at the D.C.
site also in area 0. These connect to seperate WAN distribution switches (1
wan aggregation router to one dist switch the other wan aggregation router
to the other dist switch) which connect to our core.
Placing an additional router at regional sites (similiar I would think to
your 20 remote connections) proved to be to costly and somewhat impractical
so this is what we did.
Connection to D.C. from Seattle on one 7206, connection from San Fran to
D.C. on the other 7206. Connection between Seattle and San Fran. This saves
the cost of an additional line at each site. The Connection between Seattle
and San Fran is out of a different CO. This covers the last mile at all
three sites (which is often where the trouble is and which is also out of
your control at the telco end) and the main concern shifts more towards
losing the router or interface (something that is under your control and can
be managed as quickly as you would like) and away from losing the telco
line or CO related problems for which you are at the mercy of the Telco.
It is usally the last mile that fails. This means if you are designing for
redundancy you may wish to make sure the fiber or lines that are to be
redundant links come from a different CO. Most of the time when you order
another line it will come out of the same CO and sometimes from the same
switch in the CO. Meaning if the switch or CO dies, so does your backup
solution. This is what happened to another company I worked for in N.J.
during the big rains a couple years back. They backed up all their T's with
ISDN but it all came from the same CO. So when the CO went under water they
lost their T's, the ISDN backup AND their voice lines!!!
-----Original Message-----
From: Roland Ng [mailto:lm_nguyen@hotmail.com]
Sent: Wednesday, November 14, 2001 10:49 AM
To: ccielab@groupstudy.com
Subject: OSPF Redundancy
Hi All,
If you have a gigE switch with 20 ABR to make up your area 0. How do you
provide a fail-over solution incase the switch dies? Will having another
switch and another connection for those 20 routers work?
if so, do you put them in the same area 0? or how do you do this?
anyone out there have experience in designing layer 2 redundancy?
Thanks a ton.
br/lmn
"To learn and from time to time to apply what one has learned - isn't that a
pleasure? "- Analects 1:1
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