Re: [v6ops] WGLC: draft-ietf-v6ops-unique-ipv6-prefix-per-host-02 - multiple prefixes per device

[Tim Chown <[e-mail]>]

Hi,

> On 16 Mar 2017, at 09:45, [e-mail] wrote:
> 
> Fred,
> 
>>> A little flippant perhaps, but can you give an example of a node that isn't a router anymore?
>>> I think the statement "All hosts are routers" is almost true.
>>> 
>>> Certainly my phones, laptops, lightbulbs are all routers.
>> 
>> </hat>
>> 
>> I'd like to understand your meaning, if you don't mind.
>> 
>> A router, per RFC 2460, is a system that receives a message, does no processing on its content, but repeats it to another system. A host is one that receives messages and processes their application layer content.
> 
> 2460: router      - a node that forwards IPv6 packets not explicitly addressed to itself.
> 
>> I think it's fair to say that an iPhone etc has more than one interface; WiFi and LTE, perhaps. A laptop often has several interfaces such as physical and wireless Ethernet, USB, Bluetooth, and other things. Having multiple interfaces, however, does not qualify it as a router; what qualifies it as a router is when it receives a message and repeats it, usually on another interface.
> 
> Phones act as routers when they do tethering.
> My laptop acts as a router when the hypervisor running on bare metal routes traffic between the physical NICs and a set of VMs and containers.

Indeed, there are many examples.

>> Yes, an iPhone acting as a hot spot can route between its WiFi and LTE ports. If it is not configured as a hot spot, however, it generally uses its many interfaces as ways to receive messages, pass them to applications, and respond to them. Absent a specific (and unusual) configuration, an iPhone therefore is a host, not a router.
> 
> Correct, and switching between the two requires a single swipe with suitable finger.
> And my lightbulbs, builds up a mesh and forward packets for each other. Aka router.

And the good news is that it’s all pretty transparent to the user, who just enables/disables services.

>> Are you and I using the words in the same way? I get the feeling that you see multiple interfaces and infer "router".
> 
> No.
> Sure, many nodes can be configured to act either as hosts or routers. In IPv4 the typical case is that it pretends to be a host northbound  to the network. Unfortunately that's how it is likely to pan out in IPv6 too…

So that’s a key observation - what can we do to influence that future?  I’d hope RFC 7934, and this draft, would help do so...

Tim

> 
> Cheers,
> Ole