RFC 7339: Session Initiation Protocol (SIP) Overload Control

Publisher

IETF / RFC Editor

URL

https://www.rfc-editor.org/rfc/rfc7339.html

Published

2014-09-01

Updated

unknown

Accessed

2026-09-25

HTTP status

200

License

IETF Trust Legal Provisions (BCP 78); no-redistribution; short excerpts and locators only

Source notes citing this source

• Using 503 for overload can make traffic oscillate and shift between SIP servers, worsening the overload. in context
• Under RFC 7339, an overloaded server that is throttling MUST reject some requests from non-participating clients with 503 without a Retry-After header. in context
• Under RFC 7339's default loss algorithm the oc value is a percentage from 0 to 100 by which the client must cut the requests it forwards to the overloaded server; oc-validity is in milliseconds. in context
• RFC 7339 (Standards Track, September 2014) carries overload feedback hop by hop in Via header parameters oc, oc-algo, oc-validity and oc-seq; a client adds oc to the topmost Via it inserts and the server returns a value in the response's topmost Via. in context
• RFC 7339 overload control depends on cooperating upstream clients, so it helps against legitimate overload between trusted SIP servers and is not by itself a defense against a hostile flood from sources that ignore the feedback. inferred in context
• RFC 7339 (Standards Track, September 2014) defines SIP overload control, in which a server uses the Via parameters oc, oc-algo, oc-validity and oc-seq to tell upstream clients to cut traffic, with loss-based control as the default algorithm. in context

Cite this source record

APA

WarmTransfer. (2014, September 1). RFC 7339: Session Initiation Protocol (SIP) Overload Control. WarmTransfer. https://warmtransfer.net/knowledge/sources/rfc-7339-sip-overload-control

BibTeX

@misc{warmtransfer-rfc-7339-sip-overload-control,
  title  = {RFC 7339: Session Initiation Protocol (SIP) Overload Control},
  author = {{WarmTransfer}},
  year   = {2014},
  url    = {https://warmtransfer.net/knowledge/sources/rfc-7339-sip-overload-control},
  note   = {IETF / RFC Editor, accessed 2026-09-25}
}