Hi, Joe!



Thank you for reviewing the draft and providing valuable comments. Please see 
inline for some responses.



Lin



-----Original Messages-----
From:"Joe Clarke (jclarke)" <[email protected]>
Send time:Friday, 08/02/2024 05:34:24
To: "[email protected]" <[email protected]>
Subject: [Int-area] Review of draft-bi-intarea-savi-wlan



At the INTAREA 120 meeting, Éric mentioned that since CAPWAP was a product of 
OPS, it might make sense for this work to move to opsawg.  As opsawg co-chair, 
I cannot say our WG would adopt this (that is a question for the WG), but I did 
take the time to read this draft as a contributor and a concerned WiFi 
implementor (on behalf of the IETF NOC).

 

While I think it’s a noble effort to standardize what some (most?) wireless LAN 
controllers do already today, I think there are some problems with this draft 
as it is.  First, the terminology of FIT and FAT APs was new to me.  I have 
never heard these terms.  I typically talk about lightweight (i.e., CAPWAP) APs 
or autonomous APs.   I would stick to more common terminology.  I would also 
move Access Controller (AC) to the terminology section.

 

LH>Regarding terminology, I think your suggestions are excellent, and we will 
make modifications to use more generic terms in the next version.





Those are minor compared to the two big issues I see.  The first is a 
limitation we see today with the IETF WiFi network.  That is, we want to do 
IPv6 prefix delegation to wireless clients, and we cannot since the controller 
is doing mapping like what is described in this draft and not looking at the 
results of PD leases.  How does SAVI address PD?  To me, any standard around 
wireless address validation MUST account for PD.

 

LH>In fact, we have also considered support for PD in the -03 version. Like 
described in RFC7513, ACs and APs can listen to DHCP-PD messages exchanged 

between wireless clients and DHCP servers to establish binding between secured 
MAC addresses and IPv6 prefixes for wireless clients. This is also mentioned 

in Section 10 of draft-ietf-v6ops-dhcp-pd-per-device-08.




The other big issue I see is in the signaling of MAC-IP mappings between 
autonomous APs.  You mention that the same CAPWAP signaling can be used, but I 
have never seen this happen between autonomous APs.   I’m not sure how that 
would scale, either.  Section 5.2 doesn’t really address what I feel are 
several challenges in the autonomous world.  Honestly, I haven’t seen this type 
of address validation with autonomous APs because there are so many challenges. 
 I would think this document should stay focused on the AC/lightweight modality.

 

LH>This is also a good suggestion. We did think poorly about autonomous AP 
scenarios before. Another solution we are reconsidering for autonomous AP 
scenarios

 is not to require implementation between APs as per the CAPWAP extension 
(Section 5.1.4), but to just suggest what to migrate and allow vendors 
flexibility in implementation.




Back to the question of moving this document to opsawg…this does seem to be 
somewhat of an operational concern, so I think there is applicability.  I think 
it’s worth taking to the opsawg list to see if there is interest.




LH>Good. We will take it to the opsawg.  


 

Joe




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