The MPLS WG Archive[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index][Thread Index][Author Index][Subject Index] LDP - VPN
Yes, You miss few things. LDP is NOT routing protocol, so LDP cant populete VRF tables! LDP run behind of IGP, but there are no IGP which may carry information about overlaping IP addresses (like BGP do by VPN-IPv4 NLRI). To use LDP you must develop IGP protocol. for OSPF it mean work from skrech. For IS-IS it is a little bit easier (IS-IS have also TLVs) Theoretically, it is possible to create something like VPN-IP v4 addrss family under IGP, but why do this when we have provent protocol - BGP. When We use BGP we have ext. community to limit connectivity in VPM and for for example HUB-and-SPOK topology, Central Services Topology. Generally You cant provide overlaping VPN. Theoretically, it is possible to create something like community under LDP, but why do this when we have provent protocol - BGP. Additionally, BGP gives possibility to create Interprovidr VPN. LDP domain is limited to one ISP because LDP must run in connection with IGP. Furthermore BGP is designed for realy large scale (in mean of number of routes) - other protocols not. I suggest you to read RFC2547bis but also draft-martini-l2circut-trans-mpls (this use LDP for L2 VPN information propagation), and draft-kompella-ppvpn-l2vpn (this use BGP similiar to rfc2547bis) Rafal Jan Szarecki Senior System Engineer ATM/IP Backbone Network Ericsson Poland Product and Solution Department (EPO/S) *rafal.szarecki@epo.Ericsson.se *rafal.szarecki@Ericsson.pl *+48 602 418971 '+48 22 6916635 > -----Original Message----- > From: Arun Kumar Dheena [mailto:arunkumar.dheena@wipro.com] > Sent: Friday, February 22, 2002 1:08 PM > To: mpls@UU.NET > Subject: LDP - VPN > > > Hi, > The RFC 2547bis uses BGP to distribute the VPN routes. > But, we can > modify LDP itself to carry the information carried in BGP like the VPN > routes, route targets and VPN labels etc (by defining, new > TLVs and new LDP > messages). > > The motivation for this is, firstly, the LDP-VPNs can provide the same > scalability as in mentioned RFC2547, as the intermediate > LSR's (P routers) > need not maintain the VPN-Lables and routes. (This can be achieved by > maintaining LDP sessions between the PE LSR's). Secondly, we > can avoid using > BGP for MPLS-VPNs. > > Will this apparach be an alternate for BGP/MPLS VPN? > Or am I missing something fundamental? > I want to know whether any work has been done in this direction. > > Thanks in advance. > regards > arun > > Wipro-CDC > > > > > >
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