Try removing ppp multilink and only dial out with one channel (remove the second SPID)and see if you get 56 or 64kb as you should. If so, I'm guessing the channels aren't bonding properly, and it's doing some sort of round-robining out both devices and half the packets are getting dropped/being reset, or something odd like that. I saw a simular situation where another engineer had done the config, and as soon as the second channel came up, bandwidth went down the tubes (like what you're talking about). I actually found the configs (before and after):
Original config:
interface BRI0
no ip address
no ip directed-broadcast
encapsulation ppp
dialer pool-member 1
isdn switch-type basic-ni
isdn spid1 20923610540101 2361054
isdn spid2 20923610640101 2361064
isdn incoming-voice modem
ppp authentication chap pap callin
!
interface Dialer1
description ISP
ip address negotiated
no ip directed-broadcast
no ip proxy-arp
ip nat outside
encapsulation ppp
no ip split-horizon
dialer remote-name Cisco1
dialer idle-timeout 300
dialer string 12095771091 class DialClass
dialer hold-queue 10
dialer load-threshold 10 either
dialer pool 1
dialer-group 1
pulse-time 0
ppp authentication chap pap callin
ppp chap hostname (removed)
ppp chap password 7 (removed)
ppp pap sent-username (removed) password 7 (removed)
ppp multilink
!
ip nat inside source list 1 interface Dialer1 overload
no ip classless
ip route 0.0.0.0 0.0.0.0 Dialer1
!
!
map-class dialer DialClass
access-list 1 permit 192.168.1.0 0.0.0.255
dialer-list 1 protocol ip permit
My working config (note, no Dialer interface, but no need with just one connection to the same place):
interface BRI0
ip address negotiated
no ip directed-broadcast
ip nat outside
encapsulation ppp
dialer string 1209removed class pbi64
dialer load-threshold 60 either
dialer-group 1
isdn switch-type basic-ni
isdn spid1 209removed0101 removed
isdn spid2 209removed0101 removed
no peer default ip address
no fair-queue
compress stac
no cdp enable
ppp authentication pap callin
ppp pap sent-username removed password 7 removed
ppp multilink
hold-queue 75 in
!
ip nat inside source list 100 interface BRI0 overload
ip classless
ip route 0.0.0.0 0.0.0.0 BRI0 permanent
!
access-list 100 permit ip 192.168.1.0 0.0.0.255 any
dialer-list 1 protocol ip permit
Anyway, I'd just configured a simular router 2-3 days before, and rather than troubleshoot what another lazy engineer had set up, I just wiped it and used what I knew just worked (and it did just work).
[sig][/sig]