VRF-Lite versus VLANs at access edge

Unanswered Question
Mar 16th, 2009

What would be the advantage in using VRF-Lite at the CE (e.g. a 3750 switch) and trunking a series of /30 pt-pt VLANs (one for each VRF) from the PE to the CE switch, and then defining customer VLANs on the 3750 versus defining the customer VLANs on the PE device and simply trunking the customer VLANs down to the 3750 switch. In the latter scenario, the IP Services feature set would not be required on the 3750 as VRF-Lite would not be necessary at the edge; just VLAN separation, with IP routing disabled.

A couple of possible benefits for using routed /30 links to the CE:

(i) if the routing is complex at the CE site and more subnets need to be advertised towards the PE (i.e. it's more than a single VLAN);

(ii) SP does not need to get involved in customer routing, but in a small Enterprise MPLS scenario, the customer and the provider may be one and the same, so may be less of an issue;

(iii) A dual-homed CE device may need routes advertised towards two separate PEs.

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Giuseppe Larosa Mon, 03/16/2009 - 15:22

Hello Matthew,

a multi VRF CE also known as VRF lite is a shared device: it can be partitioned between different customers reducing cost of ownership for each of them.

It is typically owned and managed by a service provider.

It can fit to multi-tenant office facilities.

If yours is an enterprise scenario and the device is not going to be shared you can save some money making the C3750 a simple L2 switch and terminating all L3 interfaces on the PE itself.

On the other hand a VRF lite CE can reduce the number of L3 interfaces that need to be defined on the PE providing a scalability advantage (every platform has a maximum number of interfaces supported regardless they are in VRF or in global routing table)

Hope to help

Giuseppe

shivlu jain Mon, 03/16/2009 - 21:53

Most of the SP use vrf lite when they provide internet access to customers.

alfredlaulaclrs Fri, 06/03/2016 - 07:58

I've used VRF lite in a situation where the customer had the same IP address space.

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