[nsp] load balancing over parallel DSL lines

[Mark E. Mallett]

Hi-

Wondering if anyone has success in doing load balancing over DSL
destinations backhauled via ATM.  Given RBE setup including this:

ip cef
!
interface atm1/0
!
interface atm1/0.301 point-to-point
 ip unnumbered loopback 1
 atm route-bridge ip
 pvc dsl-301 1/301
  encapsulation aal5snap
!
interface atm1/0.302 point-to-point
 ip unnumbered loopback 1
 atm route-bridge ip
 ip load-sharing per-packet
 pvc dsl-302 1/302
  encapsulation aal5snap

and two DSL circuits to the same customer with two different IP
addresses ip1 and ip2 on different subnets, I'd like to route
their subnet to those two destinations and have per-packet load
balancing occur.  e.g:

   ip route <subnet> <mask> <ip1>
   ip route <subnet> <mask> <ip2>

(I'm using shorthand instead of real numbers for attempted clarity)

Both ip1 and ip2 are routed over the same pvc (in this case, the 302
PVC).  

What I see is that the subnet routing goes via only one of the circuits.
And indeed:

gw> show ip cef <subnet> internal
<subnet>/xx, version 94, per-packet sharing
0 packets, 0 bytes
  via <ip1>, 0 dependencies, recursive
    traffic share 1, current path
    next hop <ip1>, ATM1/0.302 via <ip1>/32
    valid glean adjacency
  via <ip2>, 0 dependencies, recursive
    traffic share 1
    next hop <ip2>, ATM1/0.302 via <ip2>/32
    valid glean adjacency
  0 packets, 0 bytes switched through the prefix
  tmstats: external 0 packets, 0 bytes
           internal 0 packets, 0 bytes
  Load distribution: 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 (refcount 1)

I have tried a number of different options, including enabling/disabling
various sorts of route cache and applying "ip load-sharing per-packet"
to all pvcs. 

Any insight would be appreciated.

Yours,
-mm-