Re: easy to remember addresses and /etc/hosts and DNS

[Alexandre Petrescu <[e-mail]>]

Le 26/04/2019 à 12:05, Mark Smith a écrit :
> On Fri, 26 Apr 2019 at 19:54, Alexandre Petrescu
> <[e-mail]> wrote:
>>
>>
>>
>> Le 26/04/2019 à 11:46, Mark Smith a écrit :
>>> On Fri, 26 Apr 2019 at 19:28, Alexandre Petrescu
>>> <[e-mail]> wrote:
>>>>
>>>>
>>>>
>>>> Le 26/04/2019 à 06:31, Brian E Carpenter a écrit :
>>>>>
>>>>>
>>>>> Regards Brian Carpenter
>>>>>
>>>>> On 25-Apr-19 21:48, Philip Homburg wrote: ...
>>>>>> The main example you gave is somebody typing IPv6 literals while
>>>>>> sitting in a car.
>>>>>
>>>>> Indeed, we said from the very beginning (I mean 1994) that users
>>>>> should never be required to type in IPv6 addresses.
>>>>>
>>>>> Is this so hard to avoid?
>>>>
>>>> It may be easy to avoid typing IPv6 addresse when DNS was available.
>>>>
>>>> But think about three cars in a covoy; the convoy is disconnected from
>>>> the IPv6 Internet, yet fully connected on IPv6 between all computers in
>>>> the convoy.  Which of the cars should host the DNS server?
>>>>
>>>
>>> All of them.
>>
>> Mark,
>>
>> Thank you very much for the suggestion.  I will consider it.
>>
>> I would like to ask you: is multicast DNS (mDNS) working on a single
>> subnet only?  Or does it work across subnets?
>>
> 
> I'm not an expert in mDNS or related, have just read enough to know
> what problem they're solving and (very) roughly how it works.
> 
> DNS Service Discovery is intended to convey that information across subnets:
> 
> http://www.dns-sd.org/

I suppose DNS Service Discovery works ok on IPv6, and over multiple 
subnets, and that it relies on the proper use of IPv6 multicast routing 
protocols.  I never tried IPv6 multicast routing protocols on links 
involving OCB (a kind of stripped ad-hoc WiFi at 5.9GHz).

I suppose the use of DNS resolver address in RA is also an option in 
this space.  I have tried this DNS-in-RA and it works ok.

Whether DNS-in-RA, DNS-SD and mDNS should be used in cars, and how, can 
be a subject of debate.  There is a Problem Statement draft in the 
IPWAVE WG that lists in section "DNS Naming Service" some considered 
problems.

Until these things get fixed (how to use DNS in car convoy?) I need the 
manual configuration of easy to remember link-local addresses

When DNS works in car convoys, I expect other inconvenients using 
name-to-address mappings compared to IP address literals.

I might need to update the DNS servers' files with new IPv6 Link-Local 
address to name mappings, whenever a faulty interface is replaced, or 
when USB interface keys are moved, or when 1Gb Ethernet cards are 
migrated to 10Gb Ethernet.

If I am to update files, why not updating rather the computer startup 
scripts (not DNS)?  These computer startup scripts are present in all 
computers, including embedded, as unencumbered and open source.

Second,

If I use DNS names I must remember a name like:
front-Lead-First (means the IP address on the front bumper of the
                   Follower, in the subnet between Lead and First
                   Follower)
rear-Lead-First
front-First-Second
rear-First-Second
etc.
These names are too long to type.  So I would abbreviate them to:
flf
rlf
ffs
rfs
etc.

These flf, rlf, etc are no less cryptic than a literal like fe80:1::1 is.

The short IP address literals are loved and understood by more people.

>> (because the numerous computers in these three cars are not all on a
>> single subnet; they are all interconnected with IP, but there are
>> multiple subnets with routers in between).
>>
> 
> There may be other options that better suit or can be better made to
> suit what you're trying to do, such as the work done in the Homenet or
> the ANIMA Working Groups.
> 
> Autonomic networking (the focus of ANIMA WG), sounds like it might be
> working on solutions to your problem domain.
> 
> "Autonomic networking refers to the self-managing characteristics
> (configuration, protection, healing, and optimization) of distributed
> network elements, adapting to unpredictable changes while hiding
> intrinsic complexity from operators and users."

Yes, they should be considered.

I will make this suggestion in the IPWAVE WG for the Problem Statement 
draft.

Alex

> 
> 
> Regards,
> Mark.
> 
>> Alex
>>
>>>
>>> http://www.multicastdns.org/
>>>
>>> Multicast DNS
>>> https://www.ietf.org/rfc/rfc6762.txt
>>>
>>> There's also a good book on it:
>>>
>>> ""Zero Configuration Networking: The Definitive Guide
>>> https://www.amazon.com/gp/product/0596101007
>>>
>>>
>>> A number of implementations:
>>>
>>> https://www.avahi.org/ - Linux
>>>
>>> https://developer.apple.com/bonjour/ - Apple, Windows
>>>
>>> And if you want to know what inspired it,
>>>
>>> "Requirements for a Protocol to Replace the AppleTalk Name Binding
>>> Protocol (NBP)"
>>> https://tools.ietf.org/html/rfc6760
>>>
>>> This is why you need to explain your problem, not just what you think
>>> is the solution. You'll get much quicker answers.
>>>
>>> <snip>
>>>
>