RFC 2126, "ISO Transport Service on top of TCP (ITOT)", March 1997

Errata ID: 7923
Status: Reported
Type: Technical
Publication Format(s) : TEXT
Reported By: Øyvind Jonsson
Date Reported: 2024-05-05

Section 4.1.1 says:

Non-standard TPDU size may be negotiated using the negotiation
mechanism specified in ISO 8073. The maximum TPDU size is 65531
octets. The Default maximum TPDU size is 65531 octets.
Please refer to 'Notes to Implementors' section 6.4.

It should say:

Non-standard TPDU size may be negotiated using the negotiation
mechanism specified in ISO 8073. The maximum TPDU size is 65408
octets. The Default maximum TPDU size is 65408 octets.
Please refer to 'Notes to Implementors' section 6.4.

Notes:

According to X.224(1995), which is technically aligned with ISO 8073:1997, the maximum TPDU size is specified as a multiple of 128 (ref section 13.3.4.c in X.224). This allows a maximum of 511*128 = 65408. The value of 65531 is the maximum payload in RFC 2126.

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