RFC 5101, "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of IP Traffic Flow Information", January 2008
Note: This RFC has been obsoleted by RFC 7011Source of RFC: ipfix (ops)
See Also: RFC 5101w/ inline errata
Errata ID: 2791
Publication Format(s) : TEXT
Reported By: Adrian Farrel
Date Reported: 2011-04-28
Verifier Name: Dan Romascanu
Date Verified: 2011-08-02
Section 7 says:
If the length of the Information Element is greater than or equal to 255 octets, the length is encoded into 3 octets before the Information Element. The first octet is 255, and the length is carried in the second and third octets, as shown in Figure S.
It should say:
The length may also be encoded into 3 octets before the Information element allowing the length of the Information Element to be greater than or equal to 255 octets. In this case, first octet of the Lenght field MUST be 255, and the length is carried in the second and third octets, as shown in Figure S.
The original text is ambiguous as to whether it is possible to carry a length of less than 255 encoded in a 3 octet Length field. The quoted text seems to say it is not allowed, but Figure S says that the 2nd and 3rd octets may be set to "Length (0 to 65535)".
Since there is absolutely no harm (except a little inefficiency) in using a 3 octet Length field to encode a small length, the document should be clarified to remove the ambiguity.