Hello,
I did not see any reply for this comment. I seize the opportunity to clarify my opinion: I think TLV alignment statement must be a general rules for all TLVs of a given object. The draft then needs also to specify that the alignment padding bytes must be included before or after the value field. The Length field would carry the actual length of the value without padding bytes due to alignment. Those statements seem important to me for the processing of unknown TLVs. With this general rules there is no need to specify that 2 unused bytes must be added for 4 bytes length value TLV such as The REQ-MISSING. Note that Im not sure why the draft proposed a 8 bytes alignment (Why not 4 bytes since in section 7.1 it is said that object length must always be a multiple of 4?). Does it make sense? Best regards Fabien _____ De : Fabien VERHAEGHE [mailto:[EMAIL PROTECTED] Envoyé : vendredi 14 septembre 2007 09:45 À : [EMAIL PROTECTED] Objet : [Pce] TLV Format Hi, I think there is a little problem with PCEP object TLV format. The main problem being that the general format of the TLVs is not described (Type, length value length, 4 bytes alignment ). Besides for existing TLVs we have: The REQ-MISSING TLV is composed of 1 byte for the type, 1 byte specifying the number of bytes in the value field, 2 bytes for an "Unused" field (the value of which MUST be set to 0), followed by a fix length value field of 4 bytes specifying the request-id-number that correspond to the missing request. The REQ-MISSING TLV is padded to eight-byte alignment. TYPE: To be assigned by IANA LENGTH: 4 VALUE: request-id-number that corresponds to the missing request I think the LENGTH field should be set to 6, the unused field 2 bytes being part of the Value field. Otherwise it means those 2 bytes are part of the TLV header and it should be said that all TLVs will be formatted with this 4 bytes header i.e. Type (1byte) Value field Length (1byte) Unused field (2bytes) Value field Otherwise, there may be some problem when decoding a message with unknown TLV. Besides Im not sure about the The REQ-MISSING TLV is padded to eight-byte alignment. statement. Is it really needed? For the NO-PATH-VECTOR TLV we have The NO-PATH-VECTOR TLV is composed of 1 byte for the type, 1 byte specifying the number of bytes in the value field, followed by a fix length value field of 32-bits flags field used to report the reason(s) that led to unsuccessful path computation. The NO-PATH-VECTOR TLV is padded to eight-byte alignment. TYPE: To be assigned by IANA LENGTH: 4 VALUE: 32-bits flags field In this case there is no Unused field 2 bytes. I think it would be better to have the same format for all TLVs of all object. And again Im wondering if the LENGTH field should be set to 4 or 6? Can you please clarify this to me? Am I missing something? Thanks Fabien
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