ADSL multiplexing (bonding)

Hello List,

Need an advice on what type of equipment/manufacturer would one use to multiplex 2 or 4 ADSL lines?
E.g we need to get 2 ADSL line to act as one. Something like Etherchanel with Ciscos.
Any advise?

Thanks a lot in advance.

Are all these DSLs parallel to each other from the same device on the
end-site to the same device on the provider side? If not are these at
least DSL lines provided by the same DSL provider with most likely ATM
that originates at DSL provider and end on end-user dsl line site? Are
the DSL lines exactly the same speed and configuration?

william(at) wrote:

If you have direct connection (multiple ones) between two routers using
L2 then upper layer protocols (which I'll assume to be ip) can be routed easily - simply add Loopback interface to each device and multiple static routes to the other side's loopback pointing to the interface itself. (think of the way you would do ip routing for parallel connections if you could not do ethercnannel but had multiple ethernet connections). You can also just use good routing protocol that can take care of load-balancing of traffic across parallel paths such as OSPF or IEGRP or possibly do MPLS
(although it is probably an overkill).

Now the question would be which device on the user side can be used
for terminating multiple dsl lines. From cisco you could use 2600
or 3600 router with several DSL WIC cards, see
Other manufactures may well have their own boxes and cards that do
the same. You can (I probabl would...) try to build your own box
with linux or bsd as both support range of dsl cards.

We use multichannel ppp for some of our customers. They have a CPE
with two xDSL interfaces and both are transported to one chassis on
our (ISP) side. It's pretty straight forward.


Hardware-wise a Cisco 1700 will take two ADSL lines - if you want four lines you're looking at a 2600. I'm sure there are some but I'm not aware pesonally of any other vendors that supply CPE kit capable of handling multiple DSL lines.

Technology-wise, you can either use Multilink PPP or per-packet load balancing. Generally, you'll need the cooperation of the upstream ISP - although you can load balance upstream traffic using per-packet load balancing at your end, the ISP will mostly likely have unicast reverse-path turned on so will drop the packets. Obviously loadbalancing the downstream traffic requires a higher level of cooperation.

Multilink PPP is better as you get lower latency with the right settings plus less problems with out-of-order packets. However, I belive even with Multilink PPP you'll get *some* out of order packets which is quite cappable of totally crippling real-time applications such as VoIP.