Hi Jonathan,
> On Jan 19, 2016, at 00:06 , Jonathan Morton <chromati...@gmail.com> wrote:
>
>>
>> On 18 Jan, 2016, at 18:14, Michael Richardson <m...@sandelman.ca> wrote:
>>
>> Jonathan Morton <chromati...@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.
Erm, if one send probes of differing sizes, one can calculate the total
effective bandwidth even without saturating the link (which unfortunately is an
inseparable compound of ingress and egress, but will be heavily dominated by
the lower, so typically the egress. And it should be relatively simple to flood
the link while sending probes, in other words Valent’s router should be able to
create the saturatng load on demand ;)
Best Regards
Sebastian
>
> - Jonathan Morton
>
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