Re: [5gangip] Identifier size

[Dino Farinacci <[e-mail]>]

But I’d bet on 50% probability with a 120-bit identifier. But, as you say, we are old guys.  ;-)

Dino

> On Feb 1, 2018, at 8:22 PM, Robert Moskowitz <[e-mail]> wrote:
> 
> This is the wrong way to look at it.  What is the 1% probability of a collision.  At that point, a collision is going to happen.  The 50% probability is a sure bet thing.
> 
> In a possible population of 2^128, the probability of a collision reaches 1% when the population reaches
> 
> 2.7*10^18
> 
> This is a big number, but nowhere like what it takes to reach a 50% collision probability.
> 
> But this thread was on a MUCH smaller size Identifier.  You have to run the numbers and if the probability is even 0.1%, you better include a collision management piece.
> 
> Bob
> 
> On 02/01/2018 06:01 PM, Dino Farinacci wrote:
>> I keep this on my desktop, just for frequent reference. UUIDs are 128 bits.
>> 
>> Dino
>> 
>> <PastedGraphic-2.png>
>> 
>>> On Feb 1, 2018, at 2:18 PM, Robert Moskowitz <[e-mail]> wrote:
>>> 
>>> Behcet,
>>> 
>>> I was really sick with the flu and a secondary infection all of January and am only now trying to cut through the backlog.  Us older guys got to watch it...
>>> 
>>> Anyway a comment about length of Identifier.  i have a bit of experience on considering how long to make an Identifier.   For some recent examples on this and the best estimation equation on the probability of collisions, please see:
>>> 
>>> draft-moskowitz-hierarchical-hip
>>> 
>>> Since there will always be collisions, you need some collision management approach.  The above draft provides one such approach.
>>> 
>>> Just sharing a bit of my study into consequences on choosing an Identifier length.
>>> 
>>> I may get through the various responses on this original post still this week...
>>> 
>>> Oh, and I have an Excel sheet that makes using the formula easy; just ask for it.
>>> 
>>> Bob
>>> 
>>> On 01/31/2018 11:27 AM, Behcet Sarikaya wrote:
>>>> Hi Tom, all,
>>>> 
>>>> I changed this tread to identifier size issue.
>>>> 
>>>> Saleem pointed out that:
>>>> ILNPv6 will not work with more than 64 bits in the NID, and that is consistent
>>>> with RFC8200/STD86 (which refers to RFC4291, for the use of a 64 bit ID).
>>>> 
>>>> 
>>>> So my question is the identifier in identifier - locator separation equal to the interface id in RFC 8200?
>>>> 
>>>> If yes, then what happens if the UE has more than one interfaces?
>>>> 
>>>> This makes it the uniqueness of the IID and the identifier is the same problem?
>>>> 
>>>> Regards,
>>>> Behcet
>>>> On Mon, Jan 29, 2018 at 4:16 PM, Tom Herbert <[e-mail]> wrote:
>>>> On Mon, Jan 29, 2018 at 12:39 PM, Behcet Sarikaya
>>>> <[e-mail]> wrote:
>>>> > Hi all,
>>>> > Dirk and I submitted this PS draft.
>>>> > We need this to be discussed and improved. Please read and comment.
>>>> 
>>>> Hi Behcet,
>>>> 
>>>> Thanks for posting the draft. A few comments...
>>>> 
>>>> "However it can be argued that it is difficult to derive globally
>>>> unique identifiers only using 64 bits.  So it is better to use longer
>>>> identifiers, e.g. 80 bits or longer"
>>>> 
>>>> Can you elaborate on this?
>>>> 
>>>> I think the Privacy issues should be it's own section.
>>>> Identifier/locator has both pitfalls and give opportunities to improve
>>>> privacy.
>>>> 
>>>> "The use of identifiers unique for each user brings privacy issues. If
>>>> the identifier is stolen then your traffic can be unlawfully tracked,
>>>> there could be serious implications of it."
>>>> 
>>>> This is true today when devices have address or assigned a single /64.
>>>> One alternative is gives users thousands or millions of addresses
>>>> (identifier). Identifier/locator split should facilitate that. Note
>>>> that this effect is already provided by NAT since every connection
>>>> through a NAT is translated to non-trackable address/port. NAT has
>>>> some law enforcement agencies freaking out because of its strong
>>>> (inadvertent) privacy!
>>>> 
>>>> "Privacy of identifiers is especially an issue for a UE communication
>>>> with a server like Google, Facebook, LinkedIn, etc."
>>>> 
>>>> You might want to mention that simple identifier rotation [RFC4914] is
>>>> not enough these days..
>>>> 
>>>> "Privacy issue can be mitigated only if Id-Loc system has proxy mode
>>>> of operation.  In proxy mode, user traffic is intercepted by a proxy.
>>>> Proxy node which could be placed at the subnet router or site border
>>>> router.  The router tunnels the traffic to the server.  In the process
>>>> UE identifier becomes hidden and this hopefully removes privacy
>>>> issues."
>>>> 
>>>> I'm not sure what this means. Multiple identifiers per deivce should
>>>> address the privacy issue, Maybe a proxy would have the same effect?
>>>> 
>>>> "5G specific identifiers can also used to deal with privacy issues.
>>>> IMSI is known to be 64 bit and unique for each UE.  IMSI should not be
>>>> exposed to any entities.  It is like 64-identifier.  Instead
>>>> identifiers like 5G-GUTI can be used"
>>>> 
>>>> I think this is two levels. An identifier in IP identifies a node for
>>>> the purpose of being the endpoint of the communication. Something like
>>>> IMSI identifies a specific device (and hence user). In the best case
>>>> scenario, IP identifiers don't reveal the identity of users and they
>>>> can be made externally visible. IMSI is by its nature sensitive
>>>> information and only visible in a trusted domain. A mapping system
>>>> will need to map identifiers to identities (like an IMSI) so the
>>>> system needs to be secured.
>>>> 
>>>> A big item missing in this section is locator security. Fine grained
>>>> locators used in cellular system could be used to infer the
>>>> geo-location of devices and hence users, thus enabling stalkers
>>>> everywhere.  So locators need restricted visibility somehow..
>>>> 
>>>> Tom
>>>> 
>>>> 
>>>> > Also we are soliciting co-authors, please let us know.
>>>> >
>>>> > Regards,
>>>> > Dirk & Behcet
>>>> >
>>>> >
>>>> > A new version of I-D, draft-hspab-5gangip-atticps-00.txt
>>>> > has been successfully submitted by Behcet Sarikaya and posted to the
>>>> > IETF repository.
>>>> >
>>>> > Name:           draft-hspab-5gangip-atticps
>>>> > Revision:       00
>>>> > Title:          IP Issues and Associated Gaps in Fifth Generation Wireless
>>>> > Networks
>>>> > Document date:  2018-01-28
>>>> > Group:          Individual Submission
>>>> > Pages:          7
>>>> > URL:
>>>> > https://www.ietf.org/internet-drafts/draft-hspab-5gangip-atticps-00.txt
>>>> > Status:
>>>> > https://datatracker.ietf.org/doc/draft-hspab-5gangip-atticps/
>>>> > Htmlized:       https://tools.ietf.org/html/draft-hspab-5gangip-atticps-00
>>>> > Htmlized:
>>>> > https://datatracker.ietf.org/doc/html/draft-hspab-5gangip-atticps-00
>>>> >
>>>> >
>>>> > Abstract:
>>>> >    This document attempts to make the case for new work that need to be
>>>> >    developed to be used among various virtualized functions and the end
>>>> >    user which may be moving.  First a set of use cases on tunneling,
>>>> >    charging, mobility anchors are developed and then the steps of
>>>> >    proposed new work is described next.
>>>> >
>>>> >
>>>> >
>>>> >
>>>> > Please note that it may take a couple of minutes from the time of submission
>>>> > until the htmlized version and diff are available at tools.ietf.org.
>>>> >
>>>> > The IETF Secretariat
>>>> >
>>>> >
>>>> >
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>>>> 
>>>> 
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