Re: Advertisement of Equinix Chicago IX Subnet

["Cummings, Chris" <ccummings () coeur com>]

Not too sure about your topology, but I’ve had something similar bite me, so we typically put a prefix list inbound to 
deny receiving our internal prefixes from our peers. This probably doesn’t work as well if your network is less 
“eyeballish” than ours, however.

/chris



On Wed, Mar 27, 2019 at 4:37 PM -0500, "Graham Johnston" <johnstong () westmancom com<mailto:johnstong () westmancom 
com>> 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<https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net&c=E,1,HdSVqYeR7jgCV-Dur66y05aHEW-BSduVIIHYHrXZ1P6qOt3fa684wgoFR9CoVMgOpEaWMO0lwDjZkSR-n80nd7Rvcqp4MKodaGyrIDIjEhtPXiDie1SaYsyZJ9ed&typo=1>
 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?

Thanks,
graham


RIPE Info
1 RRCs see 1 peers announcing 208.115.136.0/23 originated by 
AS32703<https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS32703&c=E,1,TOo4BxuZBilA6dEeEsyArFdQvYciFoXF4XjZNU4NqyzUFPawLd-3hzV5XwlwfBLIcVRBns_GfdJCxNBaU2dYqDWisxgCxwxRPMoTfXq-TRSDQa_BgAvqRg,,&typo=1>

·         ▼RRC00 in Amsterdam, Netherlands sees 1 ASN orginating 208.115.136.0/23.AS32703

o    
▼AS32703<https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS32703&c=E,1,LPjxozPn3-dGOA9bDJB081OscbzusnfrxssBxyMbOyunZUcNyeibk_RHV8UYO3Fw77TpLU9yRsywr6KjrmyXWgKk4DQ7XRSgr1_W1SNgkfA,&typo=1>
 is seen as the origin by 1 peer.192.102.254.1

§  
▼192.102.254.1<https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2f192.102.254.1&c=E,1,fW5rffxlYLANo-g3GopSdMyHH2oIqoulMERJOjPrrdRL4Z8602v0WhaVuS6ignBPzPDgh4S05V55mLAGu_OFn1TzFyYcCpMMzTgH1ejtJmILMrcaDQDn&typo=1>
 is announcing route 
AS395152<https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS395152&c=E,1,I_iMCTImXK-T7Vj5VALSLMN6lo0N3-N2qYG7QlBHNK8oXNmPQnsp4zJy424NN2Y8z2WxSBIfaPSkLoibtnClWliVcGMhdMDsIewEnAgiZaRITyPjKA,,&typo=1>
 
AS63297<https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS63297&c=E,1,V7oySywzIc8rSc64KXotimJVgetH1G5VqJoedNuNjm9JbOYDh8qrdMlVKD12tKJtJ4STBfu9kLFuBXInbfko44ryiCz5Gy2CztDGyYXF4HJW6Jm3uPvJgOUAfTc,&typo=1>
 
AS6327<https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS6327&c=E,1,4wIITl8037dr3SSHzQmbAIwgiFe3X75-DkFAlERAGWEFjFROhFPMC2c3IGy_vChkNN-YI2OoobMvhOUKjiV9mt69N8kXl_RTvv22nZHKLJkYc59V&typo=1>
 
AS36280<https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS36280&c=E,1,_jAHKYzgyGwMDV4H1HRk1FK3bV5j_t6dSn2YfYhnhLBYub5v33-ryduZ34KVZYUy19lhSRThf8TUnUT_6V35nTMLw6SCXqY0S8bggDBKvYUg&typo=1>AS32703<https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fstat.ripe.net%2fAS32703&c=E,1,RAfxFbCQUejEFosUxg2dek9Ke5qatnE5GGjP6p2ovv1XL6hN77GlayI0Nm5jA_jRLCxzzaZQUdABGyy7HlA7bi93SIbytUbKx_49kJPC168,&typo=1>.

§  Origin: IGP

§  Next Hop: 192.102.254.1

§  Peer: 192.102.254.1

§  Community: 63297:1000

§  AS Path: 395152 63297 6327 36280 32703

§  Last Updated: 2019-03-27T17:17:19


Route-views
route-views.chicago.routeviews.org<https://linkprotect.cudasvc.com/url?a=https%3a%2f%2froute-views.chicago.routeviews.org&c=E,1,E0igNv77g9AAa2d6Uaxl8p-e1C0XIX7IzMRDUURg85DkFqIFTzckgumVyHoZqhybvGEz7rGGqi_cSc8KzJW5xx3nxdSBkfe6z_hdXiip8re7qfTpyjS1o2wzcvLw&typo=1>>
 show ip bgp 208.115.136.0
BGP routing table entry for 208.115.136.0/23
Paths: (1 available, best #1, table Default-IP-Routing-Table)
  Not advertised to any peer
  32709 32703
    208.115.136.134 from 208.115.136.134 (63.134.128.248)
      Origin IGP, localpref 100, valid, external, best
      AddPath ID: RX 0, TX 64414249
      Last update: Wed Mar 27 17:16:09 2019