I am not clear on the difference between ipv4 and vpnv4 address family concept...Please can anyone clear this Doubt

[MAnoj Kumar]

I am not clear on the difference between ipv4 and vpnv4 address family concept...Please can anyone clear this Doubt

[daniel.dib]

The IPv4 address family is for advertising IPv4 Network Layer Reachability Information (NLRI) meaning regular IPv4 networks.

The VPNv4 address family is used to advertise VPNv4 NLRI. VPNv4 address consists of 64-bit Route Distinguisher (RD) prepended to IPv4 prefix. This is to make routes unique that are in different VRFs. The NLRI also includes Route Targets (RT) which are extended communities attached to the NLRI used for defining the topology of the VPN which could be fully meshed, hub and spoke and so on. The VPNv4 family is also used to advertise the VPN label which is used so that the Provider Edge (PE) routers can know which VPN the traffic belongs to.

Daniel Dib
CCIE #37149

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[MAnoj Kumar]

Thanks Daniel , could you please explain with a topology that would clear my doubt further.....

[daniel.dib · Accepted solution]

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.

[MAnoj Kumar]

Thanks for Clearing my Doubt

[MAnoj Kumar]

Hi daniel.dib,

I am not able to see the image you have uploaded .

Kind Regards,

Manoj Kumar

[john.dejesus]

Hi Daniel, In an L3 MPLS cloud environment. at each PE-to-PE peering is it necessary to configure the regular ipv4 address family if they're only exchanging the customer's vpnv4 routes?

[scaudle]

Very informative reply.  thank you for posting this! 

[Syed Kamran Mustafa]

Hi Daniel

Thanks for sharing the info, it is very useful however i am unable to see the image - address families.png

Can you please re load this image or if u can email me on sayedkamran@yahoo.com that will be great 

many thanks 

[Lorenzo Tating]

Hi Daniel,

Unfortunately, i can't view your network diagram on both Chrome 44 and IE 10. Is there any other way to allow others like me to view this diagram? so that i can understand better your explanation. its a shame i cannot grasp it fully without the help of your diagram. :(

Diagram or no diagram, your answer is still helpful though.

[pingyekendra]

Thanks Daniel !!!