[RP-PPPoE] Choosing an access concentrator

[Rudolf Meijering]

Hi,

Yes that is what I am trying to do. Load balancing would be a plus,
but for the moment I just want to use the second ADSL modem as fail
over. It seems like two NIC's is the easiest solution. There isn't
that much of a need for what I am trying to do, it is mostly tinkering
from my part. I have an openwrt switch, so I will play around with
VLAN's to see what I can accomplish. Thanks for the pointers.

On Thu, Sep 30, 2010 at 6:37 PM, Mike <mike-rppppoe at tiedyenetworks.com> wrote:
>
>
> Rudolf Meijering wrote:
>>
>> I suppose the pppoe packet contains the ethernet mac address from the
>> adsl modem, so I would have to choose between packets with ebtables.
>>
>>
>
> Ahh, now I think I understand what you are trying to do.
>
> You have 2 adsl modems/lines connecting to the same provider and you want to
> try and do load balanceing of sorts by using both at the same time, yes?
>
> One strategy is to simply have multiple nics in the machine, with one adsl
> modem per nic. Then you could specify by interface such as 'nic-eth0' and
> 'nic-eth1' for example. Trying to do it without multiple nics (like, having
> the modems on a switch) is highly likely to be fail. Why? Most ADSL access
> concentrators will 'learn' a subscriber mac address as being behind some
> port, and then it locks it into it's mac tables. This works to secure the
> adsl network against monkey business and help thawart one subscriber port
> from being able to monkey with another. Even if the access concentrator
> isn't locking mac addresses in it's table, you'll still have the general
> problem of pppoe discovery forwarding discovery frames down both modems
> (since they'd be on the same broadcast domain), but the replies are only
> going to come back over one of them. This is because the access concentrator
> is acting like a switch - it's only going to send reply packets back to your
> source mac address over 1 port and 1 port only (eg: the last one it learned
> your mac address was on). You could perhaps try using an 802.1q vlan enabled
> switch, putting each port in a seperate vlan, and creating vlan interfaces
> on your machine with different mac addresses as well. Seems like a bit of
> work however.
>
>   Assuming you get to the point of having multiple dsl modems, then what?
> Each ppp link will have a separate ip address and it's possible to do ip nat
> so that some outbound connections go over 1 link and the rest over another.
> If however your provider has assigned you a subnet, then you may get per
> packet load balancing if their equipment sees your subnet over both links.
> This is default behavior for cisco (subject to 'maximum-paths' config
> parameter). There's additional work you would then do on your side which I
> have never done myself and can't speak to.
>
>
> -ILC
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-- 
Rudolf Meijering