PPP Multilinking over ADSL

Well the broadband where I live is shocking. Although its now managed to creep up to a staggering 6mbps, it still well below what I’d hope for in todays world. On the bright side its quiet and we overlook countryside, so I guess you can’t have it all the time. As it happens I’m not the only one with ADSL speed issues so I thought I’d do some work on PPP multi-linking the 2 lines I have installed at home into one huge virtual bundle. I’m using a Cisco 1841 with 2 x ADSL cards (HWIC). On the LNS its fine, I just add:

ppp multilink

to the Virtual Template. Now the configuration on the CPE

interface ATM0/0/0
bandwidth 1000
no ip address
no atm ilmi-keepalive
dsl operating-mode auto
pvc 0/38
  encapsulation aal5mux ppp dialer
  dialer pool-member 1
!
!
interface ATM0/1/0
bandwidth 1000
no ip address
no atm ilmi-keepalive
dsl operating-mode auto
pvc 0/38
  encapsulation aal5mux ppp dialer
  dialer pool-member 1
!
!
interface Dialer0
bandwidth 2000
ip address negotiated
ip nat outside
ip virtual-reassembly
encapsulation ppp
dialer pool 1
dialer idle-timeout 0
dialer persistent
ppp authentication chap callin
ppp chap hostname XXXXXX
ppp chap password 0 XXXXXXX
ppp multilink

When you connect it up, the sure enough there is a bundle formed and the speed when tested now gives me about 12mbps download and 2 mpbs upload – nice!

As a side note, I added the bandwidth statements to the ATM and dialer interfaces as you can see above. i also added a line to my radius file to set the bandwidth to any arbitrary number, just so long as when the bundle hooks up, it treats the lines as equal. If you don’t ‘stabilise’ it like this you will see a ‘weight’ when executing a

show ppp multilink

which gives some good output (from the CPE):

Virtual-Access3
  Bundle name: DSL1
  Remote Username: DSL1
  Remote Endpoint Discriminator: [1] DSL1
  Local Username: XXXXXX
  Local Endpoint Discriminator: [1] XXXXX
  Bundle up for 00:04:14, total bandwidth 2000, load 21/255
  Receive buffer limit 24384 bytes, frag timeout 1000 ms
  Dialer interface is Dialer0
    0/0 fragments/bytes in reassembly list
    447 lost fragments, 28586 reordered
    505/366985 discarded fragments/bytes, 0 lost received
    0xEDCC received sequence, 0x8153 sent sequence
  Member links: 2 (max not set, min not set)
    Vi2, since 00:04:14
    PPPoATM link, ATM PVC 0/38 on ATM0/0/0
    Packets in ATM PVC Holdq: 0, Particles in ATM PVC Tx Ring: 0
    Vi4, since 00:04:14
    PPPoATM link, ATM PVC 0/38 on ATM0/1/0
    Packets in ATM PVC Holdq: 0, Particles in ATM PVC Tx Ring: 0
No inactive multilink interfaces
This entry was posted in Cisco and tagged , . Bookmark the permalink.

Leave a Reply