[c-nsp] improving ADSL MLP failover

[Adam Greene]

Hi,

Finally got Multilink PPP to work with ADSL (1841 IOS 12.4(17)). Configs 
below. They're based on getting "direct pvc's" from Verizon.

When I take down either one of the ATM interfaces, the entire multilink 
bundle seems to go down for about a minute.

I wonder if I can prevent this. I'm thinking maybe assigning the client-end 
and/or ISP-end ATM pvc's to separate virtual-templates would do the trick. 
Or maybe changing the ISP-end ATM interfaces to "no ip address" (I think 
that's unrelated but maybe a good idea anyways).

I don't have access to a test environment, so any insight would be helpful 
before I try it in production.

Thanks,
Adam



=======
CONFIGS
=======


-------
ISP END
-------

interface Multilink1
 ip unnumbered Loopback0
 ppp multilink
 ppp multilink group 1
!
interface ATM1/0.2106 point-to-point
 ip unnumbered Loopback0
 pvc 2/106
  protocol ppp Virtual-Template2
 !
!
interface ATM1/0.2107 point-to-point
 ip unnumbered Loopback0
 pvc 2/107
  protocol ppp Virtual-Template2
 !
!
interface Virtual-Template2
 no ip address
 ppp multilink
 ppp multilink group 1



----------
CLIENT END
----------

interface Multilink1
 ip address x.x.x.x y.y.y.y
 ip virtual-reassembly
 ppp multilink
 ppp multilink group 1
!
interface ATM0/0/0
 no ip address
 no ip mroute-cache
 no atm ilmi-keepalive
 dsl operating-mode auto
 hold-queue 224 in
 pvc 0/35
  protocol ppp Virtual-Template1
 !
!
interface ATM0/1/0
 no ip address
 no ip mroute-cache
 no atm ilmi-keepalive
 dsl operating-mode auto
 hold-queue 224 in
 pvc 0/35
  protocol ppp Virtual-Template1
 !
!
interface Virtual-Template1
 no ip address
 ppp multilink
 ppp multilink group 1