RFC Errata
RFC 4385, "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for Use over an MPLS PSN", February 2006
Note: This RFC has been updated by RFC 5586
Source of RFC: pwe3 (int)See Also: RFC 4385 w/ inline errata
Errata ID: 1743
Status: Verified
Type: Technical
Publication Format(s) : TEXT
Reported By: Yaakov (J) Stein
Date Reported: 2009-03-26
Verifier Name: Adrian Farrel
Date Verified: 2011-08-03
Section 4, 4.1, 4.2 says:
The sequence number mechanism described here uses a circular unsigned 16-bit number space that excludes the value zero. ... o The sequence number that follows 65535 (maximum unsigned 16-bit number) is one. ... o If the sequence number on the packet is zero, the sequence integrity of the packets cannot be determined. In this case, the received packet is considered to be in order.
It should say:
The sequence number mechanism for all PW types except the TDM PWs SAToP [RFC4553], CESoPSN [RFC5086], and TDMoIP [RFC5087] use a circular unsigned 16-bit number space that excludes the value zero. The sequence numbers for TDM PWs include the value zero. ... o For all non-TDM PWs the sequence number that follows 65535 (maximum unsigned 16-bit number) is one. ... o If the sequence number on a non-TDM-PW packet is zero, the sequence integrity of the packets cannot be determined. In this case, the received packet is considered to be in order.
Notes:
The fact that the TDM PWs always require sequence number and do not give a zero value special meaning was well-known and documented in the relevant RFCs. However, this was forgotten in this document and has caused confusion to implementers.