Hi Lucy, To your below question the answer is yes. This is a flavor of CSC which standard 4364 supports just fine.
Best regards, R. > For another scenario is that, if a WAN VPN is used to interconnect DC > provider underlying networks at different sites, i.e. PE-CE case, DC provider > should be able to build a L3VPN among vPEs at DC sites directly, in which it > seems necessary to have a tunnel between a pair of vPEs. This makes that DC > GW and WAN VPN are not aware of DC L3VPN existence, which creates a true > virtual environment. vPE host address /32 is required to advertised from one > CE to another CE, will RFC4364 support this? On Wed, Oct 31, 2012 at 10:59 PM, Lucy yong <[email protected]> wrote: > Hi, Eric, Robert, and Ali, > > Thank you very much for the explanations. They are very helpful. > > You are right. The label switch path in the text means the VPN label. > Individual labels are used over each segment and swapped at ASBR in option B. > This is not related to underlying tunnel mechanism at all. ASBR1 is the next > hop for the PE1, a tunnel is terminated at ASBR. Option A, B, C are about VPN > interworking (or say virtual overlay network). > > For another scenario is that, if a WAN VPN is used to interconnect DC > provider underlying networks at different sites, i.e. PE-CE case, DC provider > should be able to build a L3VPN among vPEs at DC sites directly, in which it > seems necessary to have a tunnel between a pair of vPEs. This makes that DC > GW and WAN VPN are not aware of DC L3VPN existence, which creates a true > virtual environment. vPE host address /32 is required to advertised from one > CE to another CE, will RFC4364 support this? > > Regards, > Lucy > > > > > > > >> -----Original Message----- >> From: Eric Rosen [mailto:[email protected]] >> Sent: Wednesday, October 31, 2012 3:45 PM >> To: Lucy yong >> Cc: Robert Raszuk; [email protected]; [email protected]; >> [email protected]; [email protected] >> Subject: Re: comment on draft-fang-l3vpn-virtual-pe-framework-01 >> >> I think there's a misunderstanding of the sentence from RFC4364: "This >> procedure requires that there be a label switched path leading from a >> packet's ingress PE to its egress PE." >> >> If a VPN packet is traveling the following path: >> >> PE1--->P1--->ASBR1--->ASBR2--->P2--->PE2 >> >> where the ASBRs are supporting option B, then there is necessarily an >> LSP >> consisting of the following sequence of routers: <PE1,ASBR1,ASBR2,PE2>. >> What makes this sequence of routers an LSP is that they all operate on >> the >> "VPN label". (See section 3.15 of RFC 3031 for the precise definition >> of >> "Label Switched Path". Note that "LSP" is defined relative to the >> position >> of a particular label in the stack of a particular packet.) PE1 pushes >> on >> the label, ASBR1 swaps it with a label assigned by ASBR2, ASBR2 swaps >> it >> with a label assigned by PE2, PE2 pops it. We could call this the "VPN >> LSP", because it follows the path of distribution of a VPN-IP route. >> >> The cited text is intended to distinguish option B from option A; in >> option >> A, the sequence <PE1,ASBR1,ASBR2,PE2> is not an LSP, because ASBR2 does >> not >> distribute labels to ASBR1. >> >> > which requires two SPs pre-provisioning process that may not apply to >> > here. >> >> The LSP exists by virtue of the distribution of the labeled VPN-IP >> routes. >> >> Note that, although <PE1, ASBR1, ASBR2, PE2> is an LSP according to the >> definition in RFC 3031, each router in the sequence only has to know >> which >> router is next in the sequence; the ingress router does not need to >> know how >> to reach to the egress router. Also, there is no requirement that an >> LSP is >> used to carry packets from PE1 to ASBR1, or from ASBR2 to PE2. Either >> or >> both of those "hops" could be via a GRE tunnel, or any other method of >> transport. >> >> It's true that in a typical deployment, there is a "top-level" LSP >> <PE1,P1,ASBR1> and another "top-level" LSP <ASBR2,P2,PE2>. Neither of >> these >> is the VPN LSP; rather, each is used to carry packets from one member >> of the >> VPN LSP to the next member in sequence. But option B is independent of >> how >> packets get between adjacent members of the VPN LSP. >> >> > WAN may use MPLS LSP tunnel and DC may use IP based tunnel. >> >> That is compatible with RFC4364 option B, because the LSP >> <PE1,ASBR1,ASBR2,PE2> still exists. >> >> > This will be an issue when use IP GRE tunnels. >> >> It's only an issue if you want to have a single GRE tunnel that goes >> from >> PE1 to PE2. If that is what you want, then you should probably be >> using >> option C. Option B does not tell the ingress PE who the egress PE is. >> (Well, not unless RFC 6513/6514 is also in use ...) >> >> > Option C request set up two LSP tunnel, one from ingress PE to egress >> PE, >> > second from ingress PE to ASBR to solve the issue in IGP. >> >> In option C, the "VPN LSP" would be <PE1,PE2>. If one wants to use >> MPLS to >> move the packets from PE1 to PE2, one needs a "top-level" LSP like >> <PE1,P1,ASBR1,ASBR2,P2,PE2>; but this is not the "VPN LSP". I think >> you >> interpreted the text from RFC 4364 as requiring this top-level LSP for >> option B, but it is only intended to require the VPN LSP >> <PE1,ASBR1,ASBR2,PE2>. >> >> I'm not sure whether this makes things any clearer or not ...
