Performance Implications of Link Characteristics (pilc)

Note: The data for concluded WGs is occasionally incorrect.

Final Charter for 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


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


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


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.

Done milestones

Date Milestone Associated documents
Done Document on asymmetric network paths submitted to the IESG for publication as BCP.
Done Document on link-layer design considerations submitted for publication as BCP.
Done Draft of TCP Over Wireless document to the IESG as BCP
Done Document on low bandwidth links to IESG for publication as BCP.
Done Document on PEP capabilities and limitations submitted for publication as Informational.
Done Document on lossy links to IESG for publication as BCP.
Done Draft on asymmetric network paths.
Done Draft of PEP capabilities and limitations document.
Done Draft of link-layer design considerations document.
Done Submit Internet-Draft on long-thin networks (based on draft-montenegro-pilc-ltn-01.txt) submitted to the IESG for publication.
Done Submit Internet-Draft on significantly lossy links.
Done Submit Internet-Draft on significantly low bandwidth links.