SIP on FTTH systems

Mark Tinka mark.tinka at
Sat Feb 8 06:42:22 UTC 2014

On Saturday, February 08, 2014 04:41:55 AM Anders Löwinger 

> So, as I wrote to Mikael, don't you need to use proxy-ARP
> or proxy-ND to get devices in same L2 domain to be able
> to communicate? They are on same subnet so they will
> ARP/ND for each other.

No, you don't, and you don't want to either.

You customers will have visibility to one another at Layer 2 
if you don't enable Split Horizon, MAC-FF, Private VLAN's, 
or whatever implementation your favorite vendor uses to 
prevent inter-communication between customers in a shared 
VLAN at the AN/bridge level.

While it seems sensible, it normally isn't a good idea. The 
majority of what will take place between customers at Layer 
2 is dirt. Best to run them through a Layer 3 device 
upstream and apply appropriate filtering.

> There is no rocket science here. Scripting in
> routers/switches seems to be more common, Cisco has TCL
> and some Nexus and Arista boxes do Python.
> There is only some hooks into the control/forwarding
> plane needed to do advanced services in access.
> Forwarding plane is covered mostly by SDN so half the
> work is done.
> In a 24/48 port access switch there are few clients, so
> scripting performance is not a problem.

I'm more impressed by the braveness of this implementation, 
than the actual implementation itself, I mean.

In our case, given the number of customers in question that 
would terminate on a BNG (be it a small switch or big 
router), long term control plane performance is a huge 
concern, as well as how the hardware handles Multicast and 
other corner-case services in various topologies.

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