AW: [nsp] Dial-Backup for PPPoE-Dialer?

[p.gaspar at mobilkom.at]

Hi,

I haven't read it completely through, but this could be something for your
problem:
http://www.cisco.com/en/US/products/sw/iosswrel/ps5413/products_feature_guid
e09186a00801d862d.html

But I'm affraid it only works for 1700 yet.

Peter

> -----Ursprüngliche Nachricht-----
> Von: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net]Im Auftrag von Gert Doering
> Gesendet: Donnerstag, 12. Februar 2004 14:50
> An: cisco-nsp at puck.nether.net
> Cc: ef at space.net
> Betreff: [nsp] Dial-Backup for PPPoE-Dialer?
> 
> 
> Hi,
> 
> Cisco's concept of "dialer interfaces are always up" has its 
> merits, but
> makes certain situations quite challenging.
> 
> Imagine the following scenario:
> 
> Cisco 836, at customer premises
>   primary internet access: ADSL interface, with PPPoE (over 
> ATM over ADSL)
>   secondary access, for backup purposes: dialup via ISDN
> 
> the "standard" configuration for PPPoE access makes use of a dialer
> interface:
> 
> vpdn enable
> 
> vpdn-group pppoe
>  request-dialin
>   protocol pppoe
> 
> interface ATM0
>     dsl operating-mode annexb-ur2
> !
> interface atm0.1 point-to-point
>     description DSL-Pseudo-Dialup
>     no shut
>     pvc 1/32
>       pppoe-client dial-pool-number 1
> !
> interface Dialer1
>     description DSL-Pseudo-Dialup
>     ip address negotiated  
>     ip mtu 1492
>     ip nat outside
>     encapsulation ppp 
>     dialer pool 1
>     ppp authentication chap callin
>     ppp chap hostname XXX
>     ppp chap password YYY
> !
> ip route 0.0.0.0 0.0.0.0 dialer1 20
> 
> 
> this works fine.  Now, what to do if the ADSL line breaks?  
> The "dialer1"
> interface will *always* be "up", due to the way dialer 
> interfaces work.
> 
> One workaround we have found is to use "backup interface" from the
> ATM0 interface to a dialer2 interface (ATM0 goes down, dialer2 changes
> from "standby" to "up" and a floating static route with a 
> better distance
> than the route to dialer1 goes active).
> 
> This works well for physical line outages.  
> 
> It doesn't work for a number of other things that tend to go wrong in
> ATM/DSL/PPPoE scenarios with a wholesale/incumbent Telco in between:
> 
>  - physical line up, but ATM circuit screwed
>  - physical line up, ATM fine, but PPPoE fails to log in due to
>    NAS / radius server breakage at the Telco
> 
> in all these cases we want to have the router switch over to 
> ISDN dialup,
> but I just can't find any trick how to do that.
> 
> Other routers (Bintec comes to mind) disable the PPPoE interface for 
> a configurable amount of time after a PPP negotiation failure, and 
> subsequently fall back to the PPPoISDN interface.  Which is exactly 
> what we'd need here.
> 
> Suggestions?
> 
> gert
> -- 
> USENET is *not* the non-clickable part of WWW!
>                                                            
> //www.muc.de/~gert/
> Gert Doering - Munich, Germany                             
> gert at greenie.muc.de
> fax: +49-89-35655025                        
> gert at net.informatik.tu-muenchen.de
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