Another silly question, What does CSC stand for? Lucy
> -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of Robert > Raszuk > Sent: Wednesday, October 31, 2012 5:07 PM > To: Lucy yong > Cc: [email protected]; [email protected]; [email protected]; > [email protected]; [email protected] > Subject: Re: comment on draft-fang-l3vpn-virtual-pe-framework-01 > > 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 ...
