[c-nsp] backup quandry

Josh Duffek consultantjd16 at ridemetro.org
Wed Oct 20 16:54:40 EDT 2004


http://www.cisco.com/en/US/customer/tech/tk364/tk871/technologies_config
uration_example09186a0080211f5c.shtml

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josh duffek    network engineer
consultantjd16 at ridemetro.org
desk:              713-739-4849
mobile:            713-291-2365

> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
> bounces at puck.nether.net] On Behalf Of Charles Sprickman
> Sent: Wednesday, October 20, 2004 3:49 PM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] backup quandry
> 
> Hello,
> 
> I've been trying to come up with a decent plan to offer backup
circuits to
> customers that works well.  We have something of an odd environment
here
> and most of the solutions I've run through fall short in one way or
> another.
> 
> This is a cheap-o backup solution.  The scenario is that the client
has a
> Covad "Telextend" T1 with the backup line being a Covad SDSL.  I'm
aware
> that this offers no protection against Covad going wonky.  We
generally
> see that most of our client outages are due to Verizon mucking about
with
> things, so it actually works quite well.
> 
> On the client side we're using Netopia gear and it handles cutting
over
> the outbound traffic well.
> 
> To handle routing the client LAN block to SDSL and ADSL circuits, I
enable
> OAM management on the pvcs and add two static routes to the interfaces
> (one with lower priority).  If one of the circuits fails, the route to
> that pvc gets yanked as OAM lets us get interface up/down status.
> 
> The problem is with the "T1" circuits.  Covad brings these into T1
cards
> in their DSLAMs and the does a frame<->ATM translation there.  Sadly
they
> don't configure the DSLAM to handle any of the ATM OAM stuff for these
> circuits, so from my router I have no way of getting the status of the
T1
> circuit.
> 
> First off, any suggestions for the above scenario?  I need some way to
> determine if the T1 is up or not, but since it's a virtual circuit and
> Covad does not support the standard signalling, I don't think there's
> anything I can do there.
> 
> Second question, Covad has recently approved the Cisco 17xx series
routers
> for the Telextend service.  With one of those in place, I could run
OSPF
> over the T1 and put the SDSL router in bridge mode and also run OSPF
over
> that link.  The only problem there is that the T1 is a 1.5 Mb/s line
and
> the SDSL backup link is generally going to be a lower speed link so I
> don't want to "balance" the two lines, I want the SDSL to only be used
if
> the T1 is down.  What other options am I missing to make this happen?
I'm
> open to all sorts of nutty hackish ideas...
> 
> Thanks,
> 
> Charles
> 
> --
> Charles Sprickman
> spork at inch.com
> 
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