Re: [v6ops] IPv6 over 802.11p - no modifications required

[Alexandru Petrescu <[e-mail]>]

Hi Greg,

Thank you for the reply.

Le 03/12/2013 02:03, Greg Daley a écrit :
> Hi Alex,
>
> Increased RA rates were investigated for MIPv6, and this was not the
> preferred solution (though I submitted the text for the initial
> RFC).

I do remember the activity, although not clearly about the preference.

Yes, frequent RAs may noise slow/latent wireless links.  In 802.11p they
may lead to undesirable loss of urgent messages.

That said, it may be a matter of finding the right ratio between RA
periodicity, the link bandwidth and mandatory 0 probability of loss (for
a given geometry of the RSU deployments and speed limitations).

Currently, the Mobile IPv6 RFC6275 lowers the timer limits to e.g.
MinRtrAdvInterval 0.03 seconds (as opposed to ND's 3 seconds RFC4861).

However, that is a Mobile IPv6 specification, and it does not update the
ND spec.  Mobile IPv6 specs are not considered in RSUs of some 802.11p
deployments. (although MIP specs are considered for the Router in the
vehicle and in the HA).

This is one of the reasons why we suggest this MIP low limit of
MinRtrAdvInterval in this IPv6-over-80211p document.

> Is it applicable to use Detecting Network Attachment procedures (RFC
> 6059) instead of high rates of beacons?

This is a good question.

Is RFC6059 applicable to Router-to-Router communications (a vehicle
holds a Router which connects to another Router sitting aside the road)?

Second, it seems to me the DNA procedures are all preceded by a
mandatory initial step of 'link-layer indication', or 'link up'.  In
802.11 these indicators seem to be, by RFC4957, the receive of a link
layer message (Ass'n Reply, or Auth Reply, or similar.)

But 802.11p being a stripped-off version of 802.11, there is no Ass'n
Reply, no Auth Reply, and the SSID is always the same (all 1s, 'wildcard
BSSID').

This is the reason why I doubt about the applicability of DNA.  I may be
wrong though.

For the IEEE 802.11p specifications see the web, or otherwise just ask.

> (obviously I have a bias, but that was the evolution which brought
> about the working group: MIPv6 o 802.11 w/beacons -> basic change
> detection support in DNA)

Does basic change detection work without a link up indicator?

Alex

>
> Sincrerely,
>
> Greg Daley [phone]
>
>> Date: Mon, 2 Dec 2013 12:09:33 +0100 From:
>> [e-mail] To: [e-mail] Subject: [v6ops]
>> IPv6 over 802.11p - no modifications required
>>
>> draft-petrescu-ipv6-over-80211p-01.txt
>>
>> Hello participants to v6ops,
>>
>> Running IPv6 over 802.11p requires no modifications to the
>> protocol: it runs just as IPv6 over Ethernet does - same 0x86DD
>> Ethertype, same recommended minimal MTU, same formation of the
>> Interface ID, ...
>>
>> However, in some operational environments, some tweaks may be
>> necessary due to specificities of the link (e.g. OCB - outside the
>> context of a BSS id): frequent Router Advertisements to support
>> handover of high-speed vehicles through distanced Road-Side Units,
>> and IP security messages because the link layer has no security
>> features.
>>
>> This is what this draft describes:
>>
>> "Transmission of IPv6 Packets over IEEE 802.11p Networks" A.
>> Petrescu, R. Kuntz, P. Pfister, N. Benamar
>> http://tools.ietf.org/html/draft-petrescu-ipv6-over-80211p-01
>>
>> What do you think?
>>
>> Alex
>>
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