Re: new issue: [LL36] Combine and rework section 1.7 and 2.11 to be clearer

Alex,

Provided they are on the same link, the LL device _can_ communicate with the printer just so long as the printer has the necessary route for the 169.254.x.x network. This has been the preferred mode of operation for several successive drafts now. Communication between LL and routable hosts on the same link is perfectly possible.

I would expect a printer using mDNS to configure the necessary route automatically. Getting the IPv4LL draft to RFC status would make this even more likely!

Philip

----- Original Message ----- 
From: "Alex Karahalios" <[email protected]>
To: "Zeroconf" <[email protected]>
Cc: "Ralph Droms" <[email protected]>
Sent: Tuesday, December 16, 2003 8:19 PM
Subject: Re: new issue: [LL36] Combine and rework section 1.7 and 2.11 to be clearer


> Ralph,
> 
> Yes, I understand this, but I think the phrase you are proposing, a 
> host "MUST cease advertising the availability of the Link-Local IPv4 
> address through whatever mechanisms that address had been made known to 
> others," will make it such that a new LL IPv4 device will not be able 
> to interoperate on the network.
> 
> Take the case of a printer using mDNS, for example. A new device would 
> only get routable address information from the printer, but the new 
> device is only configured for LL IPv4 and thus is shut out of 
> communicating with the printer.
> 
> Alex Karahalios
> 
> On Dec 16, 2003, at 11:09 AM, Ralph Droms wrote:
> 
> > Well, section 1.9 of draft-ietf-zeroconf-ipv4-linklocal-10.txt,
> > "Communication with Routable Addresses", describes how two devices can
> > communicate in the case you describe, where one device has a routable
> > address and one device has a Link-Local IPv4 address.
> >
> > Of course, there's a difference between "finding" and "communicating 
> > with".
> > "Finding" printers is out of scope for Link-Local IPv4, so
> > draft-ietf-zeroconf-ipv4-linklocal-10.txt doesn't address how the 
> > computer
> > determines the printer's address, regardless of whether the printer is 
> > using
> > a routable address or a Link-Local IPv4 address.
> >
> > - Ralph
> >
> > At 10:25 AM 12/16/2003 -0700, Alex Karahalios wrote:
> >> Given the below text which specifies the a host "MUST cease 
> >> advertising the availability of the Link-Local IPv4 address", could 
> >> some explain how I would be able to make use of LL IPv4 addressing in 
> >> the following circumstances:
> >>
> >> Let's say a printer stops advertising LL IPv4 addresses because it 
> >> obtains a DHCP address. A new computer is introduced into the network 
> >> that wants to print, but it cannot obtain a routable address, so it 
> >> configures a LL IPv4 address. How is the new computer suppose to find 
> >> the printer if the printer has stopped advertising its LL address?
> >>
> >> I've asked a similar version of this question before and was told 
> >> that there are provisions in draft to address this, but the follow 
> >> text preclude this.
> >>
> >> Thanks,
> >>
> >> Alex Karahalios
> >>
> >> On Dec 16, 2003, at 10:00 AM, Ralph Droms wrote:
> >>
> >>>    If a host finds that an interface that was previous configured 
> >>> with
> >>>    a Link-Local IPv4 address is now configured with a valid routable
> >>>    address, the host MUST always use the routable address when
> >>>    initiating new communications, and MUST cease advertising the
> >>>    availability of the Link-Local IPv4 address through whatever
> >>>    mechanisms that address had been made known to others.  The host
> >>>    SHOULD continue to use the Link-Local IPv4 address for
> >>>    communications underway when the routable address was configured,
> >>>    and MAY continue to accept new communications addressed to the
> >>>    Link-Local IPv4 address.  Ways in which a valid routable address
> >>>    might be configured for the interface include:
> >
> 
>