RFC 3261 Section 7 refers to RFC 2822 (Internet Message Format), which limits the length of any line to 998 characters, and prefers a limit of 78 characters (Section 2.1.1).
RFC 2396 (URI: Generic Syntax) doesn't give limits on any component that I can find, nor does the SIP ABNF. Since RFC 2181 (Clarifications to DNS) gives a limit for a FQDN of 255 octets, I would agree with you that that limitation probably would be the most specific (and restrictive) and therefore the one that should be adhered to. RFC 2616 (HTTP/1.1) which is also referred to by RFC 3261 in Section 7 also places a 255 character limit on the URI itself, but doesn't mandate this, just lists it as a best practice (Section 3.2.1). Joel Gerber Network Specialist Network Operations Eastlink [email protected] T: 519.786.1241 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Brett Tate Sent: December-07-12 7:01 AM To: Aro RANAIVONDRAMBOLA; [email protected] Subject: Re: [Sip-implementors] FQDN length ? > I'd like to know the maximum length of FQDN within From (or Contact) > header field. I found here > (http://tools.ietf.org/rfc/rfc3319.txt) that it is restricted to 255 > octets. is this limit valid yet ? Yes; per RFC 2181, 255 octets is the limit for an FQDN. However, RFC 3261 uses hostname instead of an FQDN. Is there an RFC which directly or indirectly limits the size of hostname? For instance, I'm not sure if a .invalid hostname is restricted to being 255 octets. host = hostname / IPv4address / IPv6reference hostname = *( domainlabel "." ) toplabel [ "." ] domainlabel = alphanum / alphanum *( alphanum / "-" ) alphanum toplabel = ALPHA / ALPHA *( alphanum / "-" ) alphanum _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
