On 1/23/20 6:01 PM, Brian wrote:
Hello all. I am having a hard time trying to articulate why a Dual Home ISP should have full tables. My understanding has always been that full tables when dual homed allow much more control. Especially in helping to prevent Async routes.
If you don't have full tables you will certainly have a default route somewhere, either set statically by you or advertised by your upstream. Accidents may happen: your ISP may blackhole a destination; sometimes they adjust loads, sometimes their redundancy is not properly set up or they may have an otherwise incorrect BGP configuration. Sometimes they just mess up. If you have full tables, you will simply stop getting the advertisements for the bad destinations from the bad ISP and your routers will take care of it because they will keep getting the advertisements from the other exit. If you don't have full tables and the mistake is in a destination for which the default route is used, your traffic will most probably be lost because they don't have enough information to know a different exit and you may get a call at midnight. It may or may not happened to me. ;-) Octavio.