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Hi,
Look at the following topology which is a bit simplified.
The CE devices are located at the customer. The customer connects to these routers. For this example the customer is running eBGP with the service provider. If we start with CE1, CE1 will advertise routes to PE1. PE1 has configured peering to CE1 in the address-family ipv4 vrf customerA. Every VPN will have a VRF where routes are inserted into.
PE1 has a VPNv4 peering with PE3. In this case we have just two PEs but there would be many in a real network. In between we have P routers and from PE to P routers there is MPLS running.
Over this VPNv4 peering the PEs take the routes that are inserted into the VRFs and advertise these as VPNv4 routes with RD, RT and VPN label as well. This is what is called a MPLS L3 VPN.
In the lower part of the topology there is regular IPv4 running. CE2 has eBGP peering with PE2 in the address-family ipv4 unicast. PE2 then has an iBGP peering with PE4 which advertise the routes learned from the customers. These routes must be unique because there is no RD here that could be used.
I hope this cleared some doubts.
In case you don't know the abbrevations here is a list:
CE - Customer Edge
PE - Provider Edge
P - Provider
MPLS - Multi Protocol Label Switching
eBGP - external BGP
iBGP - internal BGP
RD - Route Distinguisher
RT - Route Target
VPN - Virtual Private Network.
Daniel Dib
CCIE #37149
Please rate helpful posts.
Hi,
Look at the following topology which is a bit simplified.
The CE devices are located at the customer. The customer connects to these routers. For this example the customer is running eBGP with the service provider. If we start with CE1, CE1 will advertise routes to PE1. PE1 has configured peering to CE1 in the address-family ipv4 vrf customerA. Every VPN will have a VRF where routes are inserted into.
PE1 has a VPNv4 peering with PE3. In this case we have just two PEs but there would be many in a real network. In between we have P routers and from PE to P routers there is MPLS running.
Over this VPNv4 peering the PEs take the routes that are inserted into the VRFs and advertise these as VPNv4 routes with RD, RT and VPN label as well. This is what is called a MPLS L3 VPN.
In the lower part of the topology there is regular IPv4 running. CE2 has eBGP peering with PE2 in the address-family ipv4 unicast. PE2 then has an iBGP peering with PE4 which advertise the routes learned from the customers. These routes must be unique because there is no RD here that could be used.
I hope this cleared some doubts.
In case you don't know the abbrevations here is a list:
CE - Customer Edge
PE - Provider Edge
P - Provider
MPLS - Multi Protocol Label Switching
eBGP - external BGP
iBGP - internal BGP
RD - Route Distinguisher
RT - Route Target
VPN - Virtual Private Network.
Daniel Dib
CCIE #37149
Please rate helpful posts.
