It's been a couple years since I've done this also, but I once worked for
a comapny where we did something very similar. We'd broadcast a default
via rip to the customer, and set the customer up with a separate isdn
router. The part I am not quite sure about is the triggering of the
ISDN. I think we would have it participate in the rip process and use
the default it got via rip, then dial out if the rip route went away.
So, everyone would use the ether of the isdn router as their gateway. An
all in one 2503 seems simpler, especially from a routing perspective,
though it doesn't protect you as well in the event of the failure of your
router.
Brian "Sonic" Whalen
Success = Preparation + Opportunity
On Mon, 22 Oct 2001, Wortendyke, Ken wrote:
> Like most environments, you've got lots of choices available for dial
> back-up.
>
> I haven't done these in a bit, but you'll want to review your requirements
> if running a dynamic routing protocol over the ISDN link, whether you'll
> need the ISDN line available for inbound/outbound for other sites, PPP
> authentication mechanics, fine tuning your dialer list, and other ISDN-line
> and PPP specific configuration issues (switch type, SPIDs, whether you'll
> need two dialer maps or not, load thresholds, etc...).
>
> Not reviewing the ISDN specific configuration commands, here's a basic
> sample utilizing floating static routes, CHAP, and the back-up interface
> command:
> username <remote hostname> password <secret>
> !
> interface serial 0
> ip address n.n.n.h 255.255.255.m
> backup interface bri0
> backup delay <activation delay in seconds> <fallback delay in seconds>
> !
> interface bri0
> ip address n.n.n.h 255.255.255.m
> encapsulation ppp
> dialer map ip n.n.n.h name <remote hostname> <dialed number> broadcast
> dialer-group 1
> ppp authentication chap
> ppp multilink
> !
> !
> ip route 0.0.0.0/0 serial0 !this is the primary default route over the
> serial link
> ip route 0.0.0.0/0 n.n.n.h 240 !this points to your ISP's ISDN interface
> !
> dialer-list 1 protocol ip permit
> !
>
> This really utilizes two techniques in one. You don't necessarily need both
> the backup interface commands and the FSR. FSR fits better if you just run
> a default static (or a couple of statics) over the primary link. Backup
> interfaces are fairly simple to implement when you'll be running dynamic
> protocols over both the primary and ISDN links. Although FSR could work if
> your floating static route replaces a network learned dynamically, there
> normally are other issues with dynamic protocols depending upon which one
> you use.
>
> Anyone else with suggestions?
>
> HTH,
> Ken W
>
> -----Original Message-----
> From: Suryadevara Venkata Raghava Rao [mailto:sukrith@www.com]
> Sent: Monday, October 22, 2001 3:55 PM
> To: cisco-nsp@puck.nether.net
> Subject: NEWBIE -- Help on Configuring backup link
>
>
> Hi Every One,
>
> We are trying to configure a ISDN backup for a leasedline(sync-dedicated).
> When ever the leased is down ISDN should dial automatically and get
> connected to an ISP and should disconnect by itself when ever leased line
> comes up.
>
> Help is appreciated.
>
> Thanks in Advance.
>
> REgards
> Venkat
>
> ------------------------------------------------------------
> WWW.COM - Where the Web Begins! http://www.www.com
>
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