Re: [DNA-BOF] BoF Last Call on DNA WG Charter/ Link ID.

[JinHyeock Choi <athene@sait.samsung.co.kr>]

Dear Alper

Thanks for clarifying comments. I think the term 'Link ID' is not clear enough. 
It's better distinguish two identifiers, 'physical link ID' and 'Network ID'. 

Kindly see my in line comments.   

Alper Yegin wrote:
> This is not what we have in the dna-l2-hints draft, but now I'm thinking
> maybe we should be talking about two different identifiers in this context.

I agree. Physical link ID and Network ID is not identical, though related. 
 
> One is the physical link ID. This can be based on the access point ID in
> 802.11, SGSN ID in GPRS, RAN ID in 3GPP2. In most of the cases, there is no
> one-to-one mapping between the physical link ID and the network-layer
> configuration parameters. This ID just identifies a physical association.

I have a question. Assume two 802.11 APs are one the same link and share 
one AR like below. 
                                               |                                   
                                           __|____                        
                                         |            |                   
                                         |   AR    |                       
                                         |___  __|                                                         
                          __________|__________________ _____       
                                    |                               |
                                __|__                      __ |__
                               | AP1 |                     | AP2 |            
                               |____ |                     |___ _|  

                              
Assume also a noce is attached to AP1. Will a node receive a different 
physical link ID if it changes an access point? 
 
> The other is the network ID. For example, VLANID in 802.11, IP
> address/subnet obtained in PDP context in 3GPP or via PPP in 3GPP2. This
> identifies a logical association between the host and an IP subnet.
>
> Now, when a link-layer event (e.g., link up) takes place, it should be
> associated with a physical link ID and possibly with a network ID. Network
> ID is optional as this info might not be available all the time (e.g., when
> VLANID is not available).

Right. 
 
> If a network ID is available, the host can quickly determine if it has
> changed subnet. If a network ID is not available, it has to play safe and
> perform network-layer discovery to detect if it needs to reconfigure.

I have an another question. It's not clear to me what it means to a node 
changes subnet. 

Does that mean
1. A new Link-layer connection is established. or 
2. The current default router is no longer reachable. or 
3. The prefixes supported on a current link has been changed.  

When all the above occurs, it's obvious a node has changed subnet. The problem 
is there may be an occurrence when some occurs while others not. 

Best regards

JinHyeock