Performance Implications of Link Characteristics (pilc)

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In addition to this official charter maintained by the IETF Secretariat, there is additional information about this working group on the Web at: -- Additional PILC Web Page
NOTE: This charter is a snapshot of the 56th IETF Meeting in San Francisco, California USA. It may now be out-of-date.

Last Modified: 2003-03-11

Spencer Dawkins <>
Aaron Falk <>
Transport Area Director(s):
Scott Bradner <>
Allison Mankin <>
Transport Area Advisor:
Allison Mankin <>
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Description of Working Group:
Erik Nordmark ( is the Technical Advisor.

The Internet network-layer and transport-layer protocols are designed to accommodate a very wide range of networking technologies and characteristics. Nevertheless, experience has shown that the particular properties of different network links can have a significant impact on the performance of Internet protocols operating over those links, and on the performance of connections along paths that include such links. This is especially of concern to the wireless networking community.

The PILC working group will produce several BCP/Informational documents. The first document will discuss considerations for link-layer designers from the perspective of best supporting existing IETF protocols will be produced. The next document will discuss the capabilities, limitations and pitfalls of 'performance enhancing proxies' (PEPs), that is, active network elements that modify or splice end-to-end flows in an attempt to enhance the performance they attain in the face of particular link characteristics. The remaining documents will either discuss the impact and mitigations for a problematic link-layer characteristic (or group of closely related characteristics), or provide overviews of which other PILC documents apply to particular problem domains.

As one of its first work items, the WG will review an existing I-D on considerations for "long, thin" networks (one of the salient characteristics of terrestrial wireless links). This will be published as a preliminary assessment of the problem domain, to be refined by later PILC documents.

All documents will identify which of their considerations remain research topics versus which are established as advanced development. Research topics will be explicitly flagged as not part of any recommendations. All documents will also identify any security implications associated with their considerations.

The working group will also serve as a forum for discussing possible modifications to IETF protocols to improve performance in environments with problematic link characteristics - however, not to the detriment of performance and stability in the general Internet, nor to undermine existing security models.

It is incumbent upon the chairs to ensure that the WG maintains good communications with other groups interested in related technology issues, such as wireless forums.

Goals and Milestones:
Done  Submit Internet-Draft on significantly low bandwidth links.
Done  Submit Internet-Draft on significantly lossy links.
Done  Submit Internet-Draft on long-thin networks (based on draft-montenegro-pilc-ltn-01.txt) submitted to the IESG for publication.
Done  Draft of link-layer design considerations document.
Done  Draft of PEP capabilities and limitations document.
Done  Draft on asymmetric network paths.
Done  Document on lossy links to IESG for publication as BCP.
Done  Document on PEP capabilities and limitations submitted for publication as Informational.
Done  Document on low bandwidth links to IESG for publication as BCP.
Done  Draft of TCP Over Wireless document to the IESG as BCP
Done  Document on link-layer design considerations submitted for publication as BCP.
Done  Document on asymmetric network paths submitted to the IESG for publication as BCP.
  • - draft-ietf-pilc-link-design-13.txt
  • Request For Comments:
    RFC3135 I Performance Enhancing Proxies Intended to Mitigate Link-Related Degradations
    RFC3150BCPEnd-to-end Performance Implications of Slow Links
    RFC3155BCPEnd-to-end Performance Implications of Links with Errors
    RFC3366BCPAdvice to link designers on link Automatic Repeat reQues (ARQ)
    RFC3449BCPTCP Performance Implications of Network Path Asymmetry
    RFC3481BCPTCP over Second (2.5G) and Third (3G) Generation Wireless Networks

    Current Meeting Report

    None received.


    None received.