With have the same gateway IP universal across routers - I can't really
help with that, and if you've got a 'hack' that is working, perhaps
stick with that.
In regards to sharing load between mikrotiks, assuming you are using
DHCP server (IPoE, since you specified no PPPoE) - my solution would
require a remote agent to use Mikrotiks API in x increments to gather
number of subscribers per router, then adjust delay-threshold (or
authoritative setting) to delay accordingly to the lowest subscriber
count Tik so it responds first. It is a definite hack-about but should
still achieve what you are after. I'd also be interested in just leaving
them all the same and letting general network fluctuations decide which
response it gets first and uses, but that has a higher possibility of
them stacking on one.
------ Original Message ------
From: "Damian Ivereigh" <d...@launtel.net.au>
To: "aus...@ausnog.net" <aus...@ausnog.net>
Sent: 13/09/2021 7:23:36 PM
Subject: [AusNOG] Spreading the load of ISP customers at Layer2
Hi guys,
We have built all our ISP infrastructure based on the NBN style doubled tagging
of services - in other words each subscriber circuit comes through on it's own
ctag. This makes separating everything really easy because we pipe each vlan
through to different BNG's. However we are now presented with a wholesaler who
does not separate each circuit, but instead just bridges them all together into
a single circuit. We can distinguish each circuit only by inspecting the DHCP
Option82 so that we can allocate the right IP address, which is fine, but it is
hard to allocate them to use a particular BNG to send and receive traffic.
By the way I am not talking dynamic load balancing just having multiple BNG
with a subsection of the customers on each one - load sharing?
Until now with double tagging, we can reuse the same gateway IP address (i.e.
the side facing the customer) on all the BNG and because each BNG only sees
it's circuits, it will only respond to arps that it should do on the vlans
assigned to it. However with all the customers on the same circuit it is
impossible for multiple BNG to have the same IP address without creating all
sorts of duplicate arps etc. We could turn off arp on all but one of the BNG
and then put up with the asymmetric routing (makes reverse path filtering
impossible) - i.e. send all upload traffic through a single BNG, but download
comes from different ones (according to what BNG they are allocated to).
I have come up with another hack by using essentially using arp spoofing where
we get a separate box to respond to the arp requests based on what the source
IP is, but I can't help wondering how others have handled this. The wholesaler
tells me there are other ISPs with 5000+ services on the single circuit (feels
like a recipe for a broadcast storm to me).
Oh and no we don't want to use PPPoE :-)
Ideas anyone?
Damian
-- Launtel - We're at your call
Tel: 1800LAUNTEL (1800528683)
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Fax: 1300784109
http://www.launtel.net.au
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