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MREN Connectivity at StarLight (By Linda Winkler)


How to Establish a New Peering with MREN's AS 22335


Additional Information







MREN has its primary connectivity site at the StarLight International/National Communications Facility, which has been designed and developed as the next generation Science, Technology and Research Transit Access Point (STAR TAP).  The following information focuses on connectivity at StarLight.

MREN Connectivity at Starlight

By Linda Winkler

MREN has impleneted  routers and multiple interconnections at the StarLight facility ( facility, which is on the Chicago, Illinois campus of Northwestern University.

MREN's Autonomous System 22335 acts as an Internet2 and National Lambda Rail "Connector."

In summary, MREN's AS 22335 aggregates the BGP sessions of all MREN participants and presenting them as a unified set of advertisements to the Internet2 network. This model is the standard one for GigaPOps followed by other regional Internet2 connections. National Lambda Rail connections are implemented selectively by special arrangements with individual organizations.

In addition, MREN's AS 22335 is tightly coupled to the StarLight ( international exchange service, with which it peers. Appropriate StarLight routes are advertised by MREN, and vice versa. Multiple other national, state-wide, and regional peerings, including with federal agency networks are vailable through this facility.

How to Establish a New Peering with MREN's AS 22335

 Here is information on how to establish a new peering with MREN's AS 22335:

1) Allocate a /30 address block from your existing address space. The low address will be used on your router, and the high address will be used on the MREN router. For example, if you allocate The first usable
address in that block is, and that address will be used  on your router. The second usable address in that block is, and that address will be used on the MREN router.

2) Configure your border router with an subinterface for use with  MREN. That subinterface should run PIM Sparse Mode and have an MTU of 9180 bytes.

3) Compose an email note and send it to to .
The Subject: line should be "MREN Peering with <Institution> (AS <AS Number>)" [Example: "MREN Peering with Argonne (AS 683)"]. That email  should include:

  • your contact information
  • the appropriate circuit information,
  • the IP prefixes you expect to advertise to MREN,
  • the /30 address space you allocated in step 1 above,
  • the IP address of your PIM Rendezvous Point for MSDP peering,
    any changes/updates to for your
    institution, and a statement that you've set up your router.
  • Any other useful information.


4) Within 2 business days we will respond to your email reporting  whether we can ping your side of the path. That email will have information added to the subject line so responses go
directly to the trouble ticket tracking system. If necessary we will work with you to debug this part of the configuration.

5) Set up MSDP and BGP peerings with the MREN router. The MREN router's MSDP address is The MREN router's BGP Autonomous System number is 22335. You should prefer the MREN routes over any commercial ISP service, probably using BGP Local Preference settings.

6) Email and request that I2 pads the AS PATH for routes advertised to you on the direct peering. This will cause your router to prefer MREN rather than the direct path, but to fall back to the direct I2 peering if there is a problem with the MREN path.

7) Wait a couple of weeks to make sure everything works as expected.

8) Send email to telling I2 that you're finished with the direct peering. I2 will then turn off their side of the peering and you can remove that configuration from your border router (and ATM switch(es) if necessary).

Additional Information

 For problems and changes with the MREN connection, the contact email address is
-- including problems that appear to be in I2 or StarLight. General discussion
should continue to be sent to

An engineering overview of the MREN / StarLight equipment, routing policy, router proxy (looking glass), and other useful information is available at:

All of the MREN and StarLight traffic graphs are now available under:



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