Subject: [rrg] Questions about ILNP

From: "Damian Lezama" <[email-masked]>
Date: Wed, 26 Nov 2008 07:13:32 -0800

Hi,

Reading
<http://www.potaroo.net/ietf/idref/draft-rja-ilnp-intro/rfcmarkup?repository
=/away/ietf&url=/away/ietf/all-ids/draft-rja-ilnp-intro-01.txt>
draft-rja-ilnp-intro-01.txt some questions came to my mind:
 
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"Identifiers are unique within the context of a given
Locator; in many cases, Identifiers might happen to be
globally unique, but that is not a functional requirement
for this proposal."

I don't understand how this works. If you can have duplicated IDs then what
happens if you have a conflict? (i.e. You move to another network where the
ID is in use by another host?). As IDs are also used to identify sessions I
also imagine trouble there.

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"There are no standardised mechanisms to update most
transport protocols with new IP addresses in use for the
session.  [NB: There is IETF work in progress to add this
capability into the Stream Control Transport Protocol
(SCTP).]"

Isn't this RFC5061 and therefore a standard more than a work in progress?

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Is this proposal suggesting that DNS should be responsible for finding the
hosts locators? Is a DNS update fast enough for that to work (i.e. with
mobility) or cached entries make it too slow?

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Thanks.

Regards,

Damian

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From: "Tony Li" <[email-masked]>
Date: Wed, 26 Nov 2008 12:22:08 -0800

Hi Damian,

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Presumably if you move to another network, you'll need to get another
identifier.  One could imagine that this could be based on DHCP, or by
manual configuration.

Note that if a network uses particular ID allocation policies (e.g., your
MAC address is your identifier), this is very unlikely.

 

5061 appears to be a proposed standard at this point.

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DNS is only responsible for the mapping function from FQDN to a set of
locators.

In previous discussions, I believe that we came to the consensus that RRG is
not trying to solve the full-blown mobility problem.  The rate of dynamism
is higher than what we'd really like to support in any mapping function.

Tony

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From: "Damian Lezama" <[email-masked]>
Date: Wed, 26 Nov 2008 12:54:33 -0800

Hi, thanks for the reply, inline text below:

From: Tony Li [mailto:[email-masked]] 
Sent: Wednesday, November 26, 2008 12:22 PM
To: 'Damian Lezama'; [email-masked]
Subject: RE: [rrg] Questions about ILNP

Hi Damian,

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Isn't this what we are trying to avoid? If I move my site to another
provider my locators change right? If they do change, can't my IDs collide
with someone else's ones?

Well, the ID identifies the host not the interface in this proposal, it says
something about generating the ID with your set of MACs, if you do this or
even if you random choose it a collision is very unlikely I agree, but the
possibility exists.

 

OK

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I read you get two things from DNS: "L" and "I" records. I assume those are
Locators and Identifiers (I don't understand why ID's in plural). My doubt
is: is DNS fast enough for solving this? To move a site to a new provider
what do I have to do? How long are invalid locators (new site to where I
still didn't move or old site after moving) in some DNS server's cache and
what is the impact of that?

In previous discussions, I believe that we came to the consensus that RRG is
not trying to solve the full-blown mobility problem. The rate of dynamism is
higher than what we'd really like to support in any mapping function.

Well, I'm new around here, I'll take that into account, thanks. But the
draft says that ILNP treats mobility as a special case of multihoming and
solves it.

Tony

Regards,

Damian

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From: "Tony Li" <[email-masked]>
Date: Wed, 26 Nov 2008 16:22:24 -0800

_____  

 

Nope.  Changing locators when you move is entirely expected and required.
Yes, your ID's could collide, which is why you might need to get new ones. 

 

Agreed.  In which case, you do a manual identifier assignment.

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Multiple identifiers are an entirely logical result of the situation that
you posited above: the host moves and gets a new ID.  DNS is fast enough for
long term moves, but is not fast enough for mobility.  Neither is any other
mapping system in any solution proposed to date.

If a host moves to a site, it needs to learn its new locators and then
advertise them through DNS (or it's clone).  Old entries in DNS will cause
connectivity faults.

Note that this is again the same, regardless of the mapping function.

 

Clearly, it can't solve arbitrarily high speed mobility.  What it can do is
to avoid the triangle routing problem.

Tony