ADSL multiplexing (bonding)

Ryan O'Connell ryan-nanog at complicity.co.uk
Mon Oct 24 10:51:03 UTC 2005


On 24/10/2005 10:22, Gregory Edigarov wrote:

> william(at)elan.net wrote:
>
>> On Mon, 24 Oct 2005, Gregory Edigarov wrote:
>>
>>> 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.
>>
>>
>> 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?
>>
> Let's think I will answer "yes"  to the questions one at a time. :-)
> I do not have the formal task description yet,  so I am  merely 
> looking for opinions on options available,
> so I could start  making decisions.


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.



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