[Bloat] cake + ipv6

[Jonathan Morton]

On Tuesday, 18 August 2020, Daniel Sterling wrote:
> As you know, I'm here cuz I have an xbox and y'all created cake, which
> I am eternally grateful for, since it makes latency go away.
> 
> But I've recently hit an interesting issue --
> 
> Microsoft (and/or akamai, or whatever) has recently started pushing
> updates to the xbox via ipv6 instead of v4.
> 
> As I'm sure you know ipv6 addresses are essentially random on the
> internal LAN as compared to v4 -- a box can grab as many v6 addresses
> as it wants, and I don't believe my linux router can really know which
> box is using which address, can it?
> 
> Which means... ipv6 breaks cake's flow isolation.
> 
> Cake can't throttle all those xbox downloads correctly cuz it doesn't
> know they're all going to/from that one device.
> 
> So I suppose this may be similar to the "bittorrent" problem -- which,
> is there a general solution for that problem?
> 
> In my case the xbox grabs more than its share of bandwidth, which
> means other bulk streaming -- that is to say, youtube and netflix :)
> -- stops working well
> 
> I can think of one general solution -- run more wires to more devices,
> and give devices their own VLAN, and tag / prioritize / deprioritize
> specific traffic that way...
> 
> But.. are there better / more general solutions?

Does this traffic at least have some consistent means of identification, such as a port number or a remote address range?  If so, you could use fwmark rules and Cake's diffserv3 mode to put that traffic in the Bulk tin, same as with BitTorrent.

I suppose it's also possible to make Cake sensitive to Layer 2 addresses (that is, the Ethernet address) for the purpose of host isolation.  That is presently not implemented, so might take a while to filter through the deployment range.