Luyuan - good luck! Lucy - CsC stands for Carrier supporting Carrier Regards, Jeff
On Oct 31, 2012, at 22:36, "Luyuan Fang (lufang)" <[email protected]> wrote: > Hi Lucy, Robert, Eric, Ali, and all, > > Thanks for your comments. > > We got hit by Hurricane Sandy very hard in NJ. We've been out of power > since Monday, with many roads blocked by downed power lines and trees, and > extensive flooding. > We have no cell phones and no landlines working. > > Lucy, I'll get to your comments as soon as the situation is under control. > Thanks for your understanding. > > Luyuan > > > On 10/31/12 6:19 PM, "Robert Raszuk" <[email protected]> wrote: > >> Section 9. Carriers' Carriers >> >> Best, >> R. >> >> On Wed, Oct 31, 2012 at 11:17 PM, Lucy yong <[email protected]> wrote: >>> 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 ... >
