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NANOG Meeting Presentation Abstract

Appropriate Layer 2 Interconnection Between IXPs
Meeting: NANOG31
Date / Time: 2004-05-25 9:00am - 9:30am
Room: Grand Ballroom
Presenters: Speakers:

Keith Mitchell, XchangePoint

Keith Mitchell is Founder and CTO of XchangePoint, a commercial operator of Internet peering and transit interconnect services in multiple European cities, and was Executive Chairman of LINX from its inception until September 2000.
Abstract: There is an increasing demand for interconnection at layer 2 between diverse network operators. The drivers for this are often economic rather than technical. There are, however, operational problems which arise from connecting distinctly-managed Ethernet switch infrastructures at layer 2.

These include risks such as broadcast storms, which have led to a number of past incidents at various internet exchanges. There are also service-level-affecting issues such as providing resilience within the limitations of spanning-tree, problem diagnosis, and fault resolution.

Where the interconnecting IXPs are located in the same facilities within a metro area (i.e. they are \"coterminous\"), there can be significant advantages from interconnecting them using native Ethernet. These include increasing peering opportunities and \"critical mass\" for their participants, reducing overall latency, and better localisation of traffic.

Services which allow interconnection and extension of non-coterminous layer-2 IXP fabrics over long-haul distances are increasingly available. Although these appear to offer a cost-effective alternative to conventional IP peering and transit arrangements, the issues outlined above lead to more acute risks and problems than the coterminous case.

In particular, use of non-native Ethernet circuit technology such as tunnelling and/or over limited capacity links can impose performance constraints and increase latency. There are also significant scaling issues with use of conventional MAC-broadcast based IP address resolution techniques, and non-global circuit identifier space.

In late 2002, XchangePoint, a commercial competitive IXP operator, and LoNAP, a mutual membership IXP association, interconnected their coterminous exchanges in London.

Several potential interconnection models and their advantages and disadvantages were considered. A VLAN-based approach has been employed which contains many of the operational risks, flexibly addresses participant requirements, and has some minor limitations. The formal interconnection agreement arrived at covers commercial, service level, AUP and operational implementation details, and the approach is likely of more widespread interest and use.

The operational experiences of connecting two established coterminous Internet Exchanges have demonstrated when and how with appropriate design this type of layer-2 interconnection can be made to work, but have also highlighted the limitations that make non-coterminous interconnect much more problematic.
Files: youtubeAppropriate Layer 2 Interconnection Between IXPs
pdfKeith Mitchell Presentation(PDF)
Sponsors: None.

Back to NANOG31 agenda.

NANOG31 Abstracts

  • Happy Packets - Initial Results
    Speakers:
    Randy Bush, IIJ; Tim GriffinIntel Research; .
    Zhuoqing MaoUniversity of Michigan; .
    Eric PurpusUniversity of Oregon; .
    Dan StutzbachUniversity of Oregon; .
  • Happy Packets - Initial Results
    Speakers:
    Randy Bush, IIJ; Tim GriffinIntel Research; .
    Zhuoqing MaoUniversity of Michigan; .
    Eric PurpusUniversity of Oregon; .
    Dan StutzbachUniversity of Oregon; .
  • Happy Packets - Initial Results
    Speakers:
    Randy Bush, IIJ; Tim GriffinIntel Research; .
    Zhuoqing MaoUniversity of Michigan; .
    Eric PurpusUniversity of Oregon; .
    Dan StutzbachUniversity of Oregon; .
  • Happy Packets - Initial Results
    Speakers:
    Randy Bush, IIJ; Tim GriffinIntel Research; .
    Zhuoqing MaoUniversity of Michigan; .
    Eric PurpusUniversity of Oregon; .
    Dan StutzbachUniversity of Oregon; .
  • Happy Packets - Initial Results
    Speakers:
    Randy Bush, IIJ; Tim GriffinIntel Research; .
    Zhuoqing MaoUniversity of Michigan; .
    Eric PurpusUniversity of Oregon; .
    Dan StutzbachUniversity of Oregon; .

 

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