Becoming as part of back-bone

[Saif]

hi guys,

Could it be possible that our enterprise edge routers became as part of internet backbone to carry other companies
traffic?

 

[alex wlide]

Its called being a transit AS. Happens all the time. with ISPs its normal but with companies its unwanted as internet traffic is passing through your network to reach another site.

One way this can happen is if you peer with multiple ISPs. The BGP routes learned from one ISP are passed through your iBGP network and advertised out to the second ISP. That ISP then sees that your network has a path to site xyz.com and starts sending traffic your way for that site.

best practice is to apply filters to your BGP config to block this from happening.

 

[Saif]

But we only advertise routes to ISPs that have been configured with network command. if we configure network command so that it
only advertise our network, this problem should not happen.