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RFC4385 and atm-encap problem RFC4385 (CW) states: If a PE negotiated not to use receive sequence number processing, and it received a non-zero sequence number, then it SHOULD send a PW status message indicating a receive fault, and disable the PW. the original text simply said If a PE does not support receive sequence number processing, then the sequence number field MAY be ignored. this new text first appeared in atm-encap draft version 08 it is not in RFCs 4448 (Ethernet), 4618 (HDLC), 4619 (frame relay) the problem is that RFC4447 (control protocol) negotiates the use of the control word (via the "C" bit) but provides no way of negotiating use of CW w/o using SN that is why SN=0 is a special case ! it enables NOT using the sequence number without signaling the fact ! |