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Pseudowire Congestion Considerations (RFC7893) Disclosure Number: IPCOM000246779D
Original Publication Date: 2016-Jun-01
Included in the Prior Art Database: 2016-Jun-30
Document File: 54 page(s) / 55K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

Y(J) Stein: AUTHOR [+2]


A pseudowire (PW) (see [RFC3985]) is a construct for tunneling a native service, such as Ethernet or TDM, over a Packet Switched Network (PSN), such as IPv4, IPv6, or MPLS. The PW packet encapsulates a unit of native service information by prepending the headers required for transport in the particular PSN (which must include a demultiplexer field to distinguish the different PWs) and preferably the 4-byte Pseudowire Emulation Edge-to-Edge (PWE3) control word.

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Internet Engineering Task Force (IETF)                        Y(J) Stein Request for Comments: 7893                       RAD Data Communications Category: Informational                                         D. Black ISSN: 2070-1721                                          EMC Corporation                                                               B. Briscoe                                                                       BT                                                                June 2016

                   Pseudowire Congestion Considerations


   Pseudowires (PWs) have become a common mechanism for tunneling

   traffic and may be found in unmanaged scenarios competing for network

   resources both with other PWs and with non-PW traffic, such as TCP/IP

   flows.  Thus, it is worthwhile specifying under what conditions such

   competition is acceptable, i.e., the PW traffic does not

   significantly harm other traffic or contribute more than it should to

   congestion.  We conclude that PWs transporting responsive traffic

   behave as desired without the need for additional mechanisms.  For

   inelastic PWs (such as Time Division Multiplexing (TDM) PWs), we

   derive a bound under which such PWs consume no more network capacity

   than a TCP flow.  For TDM PWs, we find that the level of congestion

   at which the PW can no longer deliver acceptable TDM service is never

   significantly greater, and is typically much lower, than this bound.

   Therefore, as long as the PW is shut down when it can no longer

   deliver acceptable TDM service, it will never do significantly more

   harm than even a single TCP flow.  If the TDM service does not

   automatically shut down, a mechanism to block persistently

   unacceptable TDM pseudowires is required.

Status of This Memo

   This document is not an Internet Standards Track specification; it is    published for informational purposes.

   This document is a product of the Internet Engineering Task Force    (IETF).  It represents the consensus of the IETF community.  It has    received public review and has been approved for publication by the    Internet Engineering Steering Group (IESG).  Not all documents    approved by the IESG are a candidate for any level of Internet    Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,    and how to provide feedback on it may be obtained at

 Stein, et al.                 Informational                   ...