Why using eBGP instead of MPLS to connect multiple branch office network ?

[eigrpy]

Hi We have multiple branch office networks in different locations. We connect them to each other through MPLS. but I notice some diagram where eBGP connect them to each other. Why do they use eBGP instead of MPLS to connect them to each other ? Anyone can explain it ? Thank you

[Masoud Pourshabanian]

Thanks. I think he means MPLS VPN.

[Jon Marshall]

I think you may well be right.

It was just the description of connecting remote sites together and then they function like a LAN that made me think this might not be a L3 MPLS network setup.

Jon

[Masoud Pourshabanian]

No, you can not say that. They are completely different.

MPLS VPN is also is one application of MPLS. I believe you are talking about MPLS VPN.

BGP is a routing protocol like OSPF. What does OSPF do? Just exchanging routes.

MPLS is dividing IP traffic. You can compare MPLS VPN with VLAN( you can assign different interfaces to a VLAN). In MPLS, you assign some interfaces to a virtual routing table.

How do you advertise route of different VLAN? You do it by OSPF. Can you replace OSPF with  VLAN, definitely not.

MPLS VPN is usually implemented with BGP. BGP advertises routes inside each virtual routing table.

Can you use BGP instead of OSPF in an internal network ? yes, but it is more complicated.

Can you use MPLS VPN without BGP? Yes, OSPF can advertise routes inside each virtual routing table, but it is not scalable. it does not work in large networks.

Masoud