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Hi Steward, Section 4.1 state: The structure of the flow label TLV is shown in Figure 3. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | FL | Length |F| must be zero | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: Multiple VC TLV Where: o FL is the flow label TLV identifier assigned by IANA. o Length is the length of the TLV in octets and is 4. o When F=1 a flow label will be pushed. When F=0 a flow label will not be pushed.Two questions: 1) why bits from 17~31 has to be zero? Is any place use these bits? If not, it should be defined as reserved bits.2) Is F bit useful? When label TLV is inserted, PE does not insert a flow label and any P can not change the label value. Is this a useful case in network? Regards,Lucy
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