[c-nsp] backup quandry

[Charles Sprickman]

On Thu, 21 Oct 2004, Brian Turnbow wrote:

> 3) as you mention a routing protocol, you don't necessarily need to run
> it over the DSL line but can set it up with floating statics for backup

That's interesting...  On the CPE I could do a floating static default -
if the T1 went down the primary default route would disappear.  On our end
I could do OSPF *only* on the T1 with a floating static towards the DSL
connection.  If the T1 went down, the OSPF route would be withdrawn and
the static route would take over.  Hmmm...  That sounds like a winner.

We would have to ditch the Netopias in favor of the Cisco 172x (Netopia
doesn't do ospf), but I think Covad is only charging $200 more for the
Cisco.

Thanks!

Charles

> Regards
> Brian
>
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Charles Sprickman
> Sent: mercoledì 20 ottobre 2004 22.49
> 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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