Thomas, The proposed new text does not work, most talk on VRF/VPN function/operation are not correct. Here are some points.
- VRF is not a service - it stands for Virtual Routing and Forwarding table. It is a table. - VPN is the service assuming you are talking about. VPN - Virtual Private Network. Yes, it is Virtual Network (VN) with routing isolation - so "Private". - VRF-Lite is a feature extended from BGP VPN base function to allow one CE supports multiple VPNs. - VRF-Lite only modify CE, and there is no "each hop" things performed as described in your text. - VRF-lite does not support all MPLS-VRF functionality: label exchange, LDP adjacency, or labeled packets. - To PE, there is no difference between using VRF-lite or using multiple CEs. Thomas Morin made more good comments to you already. BTW, you mentioned that "...I didn't realize that MPLS had adopted the VRF terminology...". This does not make any sense. VRF is part of MPLS/BGP VPN technology, it did not exist before. VRF-Lite is one of the ways to configure CE. Luyuan > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of > Thomas Narten > Sent: Tuesday, July 03, 2012 9:44 AM > To: Stiliadis, Dimitrios (Dimitri) > Cc: [email protected] > Subject: [nvo3] VRFs [was Re: call for adoption: draft-narten-nvo3- > overlay-problem-statement-02] > > "Stiliadis, Dimitrios (Dimitri)" <[email protected]> > writes: > > > I believe that Section 3.1 needs to be significantly revised since it > > has some confusing statements. I cannot support this draft without a > > revision of this Section: > > I'll assume that since you didn't comment about the first two > paragraphs (L2 VLAN stuff), you are OK with that text. > > > VRF's are a pure routing construct and do not have end-to-end > > significance in the sense that the data plane carries a VRF > > indicator on an end-to-end basis. > > You're right. When I wrote this text, I didn't realize that MPLS had > adopted the VRF terminology. What the text refers to is what others > have pointed out is known as VRF lite. > > Now I understand why this text produced such a backlash. :-) > > Proposed new text: > > <t> > In the case of IP networks, many routers provide a Virtual > Routing and Forwarding (VRF) service commonly known as "VRF > Lite". The same router operates multiple instances of > forwarding tables, one for each tenant. Each forwarding > table instance is populated separately via routing > protocols, and adjacent routers encapsulate traffic in a way > that identifies the tenant (e.g., using a VLAN tag). Each > VRF Lite instance provides address and traffic isolation. > The VRF Lite instance for each frame is selected based on > that tenant identification. > </t> > > <t> > VRF's are a pure routing construct and in VRF Lite do not > have end-to-end significance in the sense that the data > plane carries a VRF Lite instance selector on an end-to-end > basis. Instead, the VRF Lite instance to be used is > determined at each hop using a combination of incoming > interface and some information in the frame (e.g., local > VLAN tag). Furthermore, the VRF Lite model has typically > assumed that a separate control plane (e.g., based on a > routing protocol) governs the population of each forwarding > table. Thus, the VRF Lite model assumes multiple, logically > independent control plane instances and has no specific tag > within a data frame to identify the VRF Lite instance for > that frame. > </t> > > <t> > MPLS VRFs <xref target="RFC4364"></xref> place the VRF > functionality on the CE and PE devices, using MPLS > encapsulation to preserve tenant separation between the CE > and PE devices. Control plane protocols (e.g., > LDP<xref target="RFC5036"></xref>) are used to set up the > data path between PE and CE. > </t> > > Does that work? > > Thomas > > _______________________________________________ > nvo3 mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/nvo3 _______________________________________________ nvo3 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nvo3
