Re: [Cerowrt-devel] routers you can throw off the back of a truck

[Jonathan Morton <chromatix99@gmail.com>]

> On 18 Jan, 2016, at 18:14, Michael Richardson <mcr@sandelman.ca> wrote:
> 
> Jonathan Morton <chromatix99@gmail.com> wrote:
>> I haven’t yet found a robust way to automatically sense link capacity from
>> the upstream side.  You’ll therefore need to set a conservative static
>> value for the uplink capacity.
> 
> As the maintainer of a PPPoE concentrator, and operator of some networks,
> I've been considering whether one can estimate the bandwidth using round
> trip PPP IPCP keep alives.   Clearly, if both ends participate in time
> stamping then it is much better, but I've been wondering if we can do some
> incremental deployment on one side or the other.
> 
> Sadly, I mostly just think about this while cycling; I haven't written any
> code yet.

In most PPPoE deployments I know about, there is also a modem from which the actual, precise link rates can usually be queried.  Where that’s not the case, IPCP (or is it LPCP?) probes would be a reasonable workaround, but it must still be understood that the signal it provides is only valid under saturating traffic, which complicates implementation.

 - Jonathan Morton