nanog mailing list archives

Re: [NANOG] Multihoming for small frys?


From: Heather Schiller <heather.schiller () verizonbusiness com>
Date: Wed, 21 May 2008 13:08:06 -0400

William Herrin wrote:
Hi folks,

An administrative question about multihoming:

I have a client who needs to multihome with multiple vendors for
reliability purposes, currently in the Northern Virginia area and
later on with a fail-over site, probably in Hawaii. They have only a
very modest need for bandwidth and addresses (think: T1's and a few
dozen servers) but they have to have BGP multihoming and can afford to
pay for it.

The last I heard, the way to make this happen was: Find a service
provider with IP blocks available in ARIN's set of /8's that permit
/24 announcements (networks 199, 204-207), buy a circuit and request a
/24 for multihoming. Then buy circuits from other providers using that
ISP's /24 and an AS# from ARIN.

Yes, but the order is wrong..

- Order service from 2 providers
- Request an ASN from ARIN, show them your documentation that you are getting service from 2 providers to justify your need for an ASN - If you don't meet the utilization requirements for getting a /24, request a /24 for multihoming under ARIN 4.2.3.6. from ONE of your providers (not both).

At UUnet/VZB we ask customers to provide their ASN as documentation that they have demonstrated their intent to multihome.

If you have existing IP space, and it's less than /24 don't be surprised if someone asks you to renumber. If you have existing IP space /24 or larger, don't be surprised if someone turns you down under the multihoming policy.


http://www.arin.net/policy/nrpm.html#four236

4.2.3.6. Reassignments to multihomed downstream customers

Under normal circumstances an ISP is required to determine the prefix size of their reassignment to a downstream customer according to the guidelines set forth in RFC 2050. Specifically, a downstream customer justifies their reassignment by demonstrating they have an immediate requirement for 25% of the IP addresses being assigned, and that they have a plan to utilize 50% of their assignment within one year of its receipt. This policy allows a downstream customer's multihoming requirement to serve as justification for a /24 reassignment from their upstream ISP, regardless of host requirements. Downstream customers must provide contact information for all of their upstream providers to the ISP from whom they are requesting a /24. The ISP will then verify the customer's multihoming requirement and may assign the customer a /24, based on this policy. Customers may receive a /24 from only one of their upstream providers under this policy without providing additional justification. ISPs may demonstrate they have made an assignment to a downstream customer under this policy by supplying ARIN with the information they collected from the customer, as described above, or by identifying the AS number of the customer. This information may be requested by ARIN staff when reviewing an ISP's utilization during their request for additional IP addresses space.


Is that still the way to make it happen? Are there alternate
approaches (besides DNS games) that I should consider?

Who should I talk to? Certain well-known companies seem incapable of
discussing service that isn't cookie-cutter.


It's really pretty straightforward and common actually... but I wouldn't be surprised if sales folks don't know ARIN and/or routing policy.


Thanks,
Bill Herrin




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~*~*~*~*~*~*~*~*~*~*~*~
 Heather Schiller
 Customer Security
 IP Address Management
 1.800.900.0241
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