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[STDS-802-11-TGBE] Feedback on doc 11-21/228

 

Hi Rojan,

 

Thank you for your contribution on Proxy ARP and addressing.

 

As we discussed offline, I have several concerns with the proposal.

 

  1. It is mandating proxy ARP for all EHT APs

 

  1. The proposal is changing the behavior of Proxy ARP service. It requires the AP to identify the requester’s capabilities and the link it is operating on. Based on this determination, the AP can respond with a different value of MAC address for the same IP address:
    1. If the request originated from a legacy STA, and

                                                    i.     If the non-AP MLD had a STA operating on the link where the legacy STA is operating on then, the AP responds back with the link MAC address of the non-AP MLD .

        • In this case, the legacy STA binds the non-AP MLD's IP address to the link MAC address of the non-AP MLD

                                                   ii.     Else the AP responds with the MAC address non-AP MLD

        • In this case the legacy STA binds the non-AP MLD’s IP address to the MLD MAC address of the non-AP MLD
    1. If the request came from another non-AP MLD or from a device on the DS, the AP responds with the non-AP MLD’s MAC address

 

  1. In addition, for a frame that originated from a non-AP MLD, the proposal requires the AP to set the SA field differently based on the intended recipient of the frame
    1. If the recipient is a legacy STA operating on one of the link where the non-AP MLD has setup a link with the AP, the SA set to link MAC of the non-AP MLD
    2. Else the SA is set to the MLD MAC address of the non-AP MLD

 

  1. AP MLD needs to do a reverse translation when it receives a frame from legacy STA addressed to a non-AP MLD

 

The above requirements put a heavy burden on the AP MLD.

Also, responding with different MAC address for the same IP address can have other ramifications.

 

 

Our proposal in doc 240 does not put any additional requirements on the AP and the entire TDLS operation is transparent to the AP. It is in line with the AP’s processing of a packet arriving from the backhaul, where translation of MLD MAC address to link MAC address needs to be performed. In addition, Proxy ARP remains an optional feature at the AP MLD. If the AP MLD supports proxy ARP, the ARP response is always consistent regardless of who made the request (a non-AP MLD’s IP address is always mapped to the same value which is the MAC address of the non-AP MLD). Furthermore, the setting of the SA field at the AP is consistent for all frames originating at the non-AP MLD (i.e., SA is always set to the MAC address of the non-AP MLD) regardless of who is the recipient.

 

Regards,
Abhi

 

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