Advertisement of Equinix Chicago IX Subnet

Thu Mar 28 14:21:43 UTC 2019

On Wed, Mar 27, 2019 at 09:36:20PM +0000, Graham Johnston wrote:
> This afternoon at around 12:17 central time today we began learning
> the subnet for the Equinix IX in Chicago via a transit provider; we
> are on the IX as well. The subnet in question is 208.115.136.0/23.
> Using stat.ripe.net I can see that this subnet is also being learned
> by others, see the snip below. On our network this caused a nasty
> routing loop until we figured out what was wrong. My current best
> understanding is that because the route was learned via eBGP it
> trumped the OSPF learned route. As soon as I filtered the
> advertisement from my transit provider everything returned to normal.
> What am I doing that isn’t best practices that would have prevented
> this?

There is two pieces to help prevent this type of failure:

1/ Equinix should have created a RPKI ROA for 208.115.136.0/23, with an
   Origin ASN of 0 or one of their own ASNs, and a Max Length of 23.

2/ You should implement RPKI based BGP Origin Validation in your network
   and honor those ROAs.

Kind regards,

Job