[netlmm] Retransmitting a PBU when HI=1 and MN LL ID is non-zero (draft-ietf-netlmm-proxymip6-18)

["Tero Kauppinen" <[e-mail]>]

Hello

Let's consider the following case where MAG sends a PBU where HI=1
(Attachment over a new interface) and MN LL ID is non-zero (no HNP).
When LMA receives the initial PBU it creates a new BCE and sends back a
PBA. If that PBA is lost, MAG will retransmit the PBU. If MAG leaves HI
to 1 (I didn't find any indication from the spec that it should do
otherwise) and retransmits the request, LMA will come to a conclusion
that this is 'Binding Lifetime Extension - After handoff'. This because:

Section 5.4.1.1. skipped (no HNP)
Section 5.4.1.2. hit (MN LL ID non-zero) checks 1) and 2) match -> a
request for updating an existing Binding Cache entry
Section 5.3.1. check 13 results in the third option (Binding Lifetime
Extension - After handoff) because HI=1

However, if HI would be set to a value of 5 (Handoff state not changed)
for retransmissions, LMA would choose (Binding Lifetime Extension- No
handoff) which I think should happen in this case. However, I'm still a
bit unsure if this would break some other cases. Even if the initial PBU
is not received by LMA, setting HI to 5 would result in the correct
behavior because there is no existing BCE with matching {MN ID, AT, MN
LL} triplet and thus LMA will create a new BCE regardless of the value
of HI.

Br,

Tero Kauppinen                                 Tel: [phone]
Research Scientist, NomadicLab, IP Networks,   Fax: [phone]
Ericsson Research, Corporate Unit.             Mobile: [phone]
Oy L M Ericsson Ab
mailto:[e-mail] 
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