Hi Dhruv, Thanks for your quick reply.
I have added PCE WG in this mail. More inline. Thanks & Regards, Mrinmoy On Tue, Mar 24, 2020 at 6:00 PM Dhruv Dhody <[email protected]> wrote: > Hi Mrinmoy, > > I was suggest you to also include [email protected]; WG could benefit from > the discussion in future. More inline. > > On Tue, Mar 24, 2020 at 5:08 PM Mrinmoy Das <[email protected]> > wrote: > > > > Respected Authors and Contributors, > > > > Hope you all are doing well and safe in this tough times of Corona Virus > Outbreak. > > > > I like to draw your attention regarding some parts of > draft-ietf-pce-binding-label-sid-02 which I didn't able to understand > properly. > > > > 1. BT = 0: The binding value is an MPLS label carried in the format > > > > specified in [RFC5462] where only the label value is valid, and > > other fields (TC, S, and TTL) fields MUST be considered invalid. > > The Length MUST be set to 7. > > > > > > Previous versions of private draft uses 4 byte to store MPLS 20 Bit > label and ignores TC, S & TTL fields. > > The length in the previous version was 6, which was incorrect. The TLV > length is as per https://tools.ietf.org/html/rfc5440#section-7.1 > Which didnt make sense and your calculation below is correct! > > > But in IETF draft after TLV structure redefinition, total length of > the TLV becomes 7, i.e. BT(1 Byte)+Reserved(3 Byte)+MPLS 20bit Label(3 > Byte) = 7 Byte > > Yes > > > So, now MPLS 20 Bit Labelwill be stored in 3 byte. Is it correct? > > You can consider it a case of rounding up 20 bits to 3 bytes. > > If this is correct then I feel the wording of the above paragraph > needs to be more specific, meaning in 3 Byte Label there will be no space > for TTL, so > > my suggestion is to make below correction: > > > > BT = 0: The binding value is an MPLS label carried in the format > > > > specified in [RFC5462] where only the label value is valid, and > > other fields (TC, S, and TTL) fields MUST be considered invalid. > > The Length MUST be set to 7. > > > > My suggestion would be not mention any of the other fields and talk > only of 20 bits of Label. I see other SR RFCs take similar approach. > Sounds Good. I'm agree with you. > > > > 2. In some cases, a stateful PCE can request the PCC to allocate a > > > > binding value. It may do so by sending a PCUpd message containing an > > empty TE-PATH-BINDING TLV, i.e., no binding value is specified > > (making the length field of the TLV as 2). A PCE can also make the > > request PCC to allocate a binding at the time of initiation by > > sending a PCInitiate message with an empty TE-PATH-BINDING TLV. > > > > > > As per new Binding TLV Structure below, BT is of 1 Byte and there will > be 3 Byte Reserved. > > > > 0 1 2 3 > > > > 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > | Type | Length | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > | BT | Reserved | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > ~ Binding Value (variable length) ~ > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > > > > Now, an empty Binding TLV should have length of BT(1 Byte) + Reserved > (3 Byte) = 4 Byte instead of 2 Byte. > > > > So, I do not understand how in the draft it is calculated as 2 Byte. > Could you please give me some clue? > > > This seems to be an error IMHO. 4 seems to be correct. > Okay. So what would be your suggestion to developer who is implementing this draft? Should it be taken as 4? If draft needs correction when will that be published? > > Thanks! > Dhruv > > > > > Thanks & Regards, > > Mrinmoy >
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