Route-Policy for VPNV4 routes

ViktorG · Created Feb 17, 2019 09:09:50

Hello mates!

Will try to make the long story short :)
MP-BGP follows almost the same route selection and loop prevention rules as BGP unicast.
So there is no traffic between B and C as the iBGP rules play here – if Received form iBGP do not send to other iBGP (iBGP Split horizon). In other words If A sent route 10.1.1.0 /24 to both B and C – B and C never send this route to each other, unless you introduce Route reflectors in your topology. (You can make Confederation but no sense with only three routers.)
If you want to play with diverse paths or to make load sharing between next hops (After you have RR) – you need to take into account BGP attributes which will help you to choose one next hop over the other ones. But again – everything is simple if you consider the rules for BGP network design.
In your situation If link between Router A and Router B will broke Traffic will not pass automatically to Router B because of the described iBGP split horizon rules.

Take care and have a great day!

chenhui · Created Feb 15, 2019 14:35:38

@wildwolf hi,
in fact, I'm not sure about your network topology, I tried with three routers run bgp vpnv4 routes and using four vpn-instance, I found that if two vpn-instance created on the router A, then the routes can not be advertised to B&C simultaneously, if one vpn-instance created on the router A, both B and C connect to the vpn-instance, then there is no difference with the common situation.

chenhui · Created Feb 15, 2019 14:36:27

maybe you can upload your image network topology,

ViktorG · Created Feb 17, 2019 09:09:50

Hello mates!

Will try to make the long story short :)
MP-BGP follows almost the same route selection and loop prevention rules as BGP unicast.
So there is no traffic between B and C as the iBGP rules play here – if Received form iBGP do not send to other iBGP (iBGP Split horizon). In other words If A sent route 10.1.1.0 /24 to both B and C – B and C never send this route to each other, unless you introduce Route reflectors in your topology. (You can make Confederation but no sense with only three routers.)
If you want to play with diverse paths or to make load sharing between next hops (After you have RR) – you need to take into account BGP attributes which will help you to choose one next hop over the other ones. But again – everything is simple if you consider the rules for BGP network design.
In your situation If link between Router A and Router B will broke Traffic will not pass automatically to Router B because of the described iBGP split horizon rules.

Take care and have a great day!

Route-Policy for VPNV4 routes

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Route-Policy for VPNV4 routes

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