Pseudowire Congestion Considerations (RFC7893)
Original Publication Date: 2016-Jun-01
Included in the Prior Art Database: 2016-Jun-30
Internet Society Requests For Comment (RFCs)
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.
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 http://www.rfc-editor.org/info/rfc7893.
Stein, et al. Informational ...