Hi Lizhong, Please also take into consideration the Ops Dir review of this doc, in which I have similar concerns as those from Joel. There seem to be three major areas in discussion: 1. The scope of the problem being solved (i.e., which cases are solved, which are not, and which are the common cases) 2. The mechanism itself not working in many cases. 3. How this all works with IPv6 addresses (since your fix seems to cover the overlapping IPv4 private address case only) Thanks, Carlos. > On Oct 22, 2014, at 10:05 AM, lizho.jin@xxxxxxxxx wrote: > > Joel, thank you for the review. We will send out a new version soon to reflect the discussion. > > Regards > Lizhong > > > >> 在 2014年10月22日，下午9:30，Joel Halpern Direct <jmh.direct@xxxxxxxxxxxxxxx> wrote： >> >> It would be good to see a revision that clearly spelled out what the >> draft was solving, how the initial end-point knew what to create, and >> how the responder knew what to use. It may well be that there is an >> effective solution to the problems here. I look forward to seeing it in >> writing. >> >> Yours, >> Joel >> >>> On 10/22/14, 12:46 AM, Lizhong Jin wrote: >>> Hi Joel, >>> The things may not be that bad. You could add a second address (address B in >>> our example) with K bit set. The address entry with K bit set must be as a >>> relay node, and could not be skipped. >>> Section 4.4 should be changed to: Find the first routable address A, and the >>> first address B with K bit set. If address A is before address B in the >>> stack, then use address B as the relay address. Otherwise, use address A as >>> the relay address. >>> In that case, if A is the private address, the packet will be firstly >>> relayed to address B. And address A and B belong to one router. Here I >>> assume one router at least has one routable address for another AS. >>> >>> Regards >>> Lizhong >>> >>>> -----Original Message----- >>>> From: Joel M. Halpern [mailto:jmh@xxxxxxxxxxxxxxx] >>>> Sent: 2014年10月22日 11:14 >>>> To: Lizhong Jin >>>> Cc: gen-art@xxxxxxxx; mpls@xxxxxxxx; ietf@xxxxxxxx; >>> 'draft-ietf-mpls-lsp-ping- >>>> relay-reply.all' >>>> Subject: Re: [mpls] [Gen-art] review: >>> draft-ietf-mpls-lsp-ping-relay-reply-04 >>>> >>>> ou are saying that this is only for the case where an AS is using public >>>> addresses for its internal numbering, but is not distributing that address >>> block >>>> externally? >>>> >>>> If so, you need to state that very clearly. >>>> I believe a far more common case is one where the numbering is from a >>>> portion of a publicly allocated space, but firewalled. Which would >>> produce >>>> the same problem, but would not be amenable to this solution. >>>> And it is well known that many ISPs do internal number assignment from >>>> private blocks. >>>> >>>> So what you are now saying is that this draft solves a very small portion >>> of the >>>> problem? But it works for that small portion? If so, at the very least >>> you >>>> need to be VERY clear about what cases this works for and what cases it >>> does >>>> not. And I fear that even if you are clear, it is going to be very >>> confusing for >>>> folks who are trying to use it. >>>> >>>> Yours, >>>> Joel >>>> >>>>> On 10/21/14, 10:51 PM, Lizhong Jin wrote: >>>>> Hi Joel, >>>>> I now see your concern. The "private" word in draft is not correct, I >>>>> will remove it. The original motivation of "draft-relay-reply" is from >>>>> the scenario where IP address distribution is restricted among AS or IGP >>>> area. >>>>> And the IP address is not private address. As I know, most deployed >>>>> inter-AS or inter-area MPLS LSP is in the network without private IP >>> address. >>>>> >>>>> Regards >>>>> Lizhong >>>>> >>>>> >>>>>> -----Original Message----- >>>>>> From: Joel M. Halpern [mailto:jmh@xxxxxxxxxxxxxxx] >>>>>> Sent: 2014年10月22日 10:15 >>>>>> To: Lizhong Jin >>>>>> Cc: gen-art@xxxxxxxx; mpls@xxxxxxxx; ietf@xxxxxxxx; >>>>> 'draft-ietf-mpls-lsp-ping- >>>>>> relay-reply.all' >>>>>> Subject: Re: [mpls] [Gen-art] review: >>>>> draft-ietf-mpls-lsp-ping-relay-reply-04 >>>>>> >>>>>> The problem is that the original source A, that we are trying to >>>>>> reach >>>>> with a >>>>>> reply, has an address that appears to the responder X to be routable. >>>>>> But the destination that is reached by that address is either a black >>>>>> hole or >>>>> some >>>>>> other entity using the same address. >>>>>> >>>>>> The reason for the duplication is that, as described in the draft, >>>>>> the >>>>> source >>>>>> address for A is a private address. That same address may well be >>>>> reachable >>>>>> according to the routing table at X. But it won't get to A. >>>>>> >>>>>> If the problem is something other than private addressing preventing >>>>>> reachability, it is likely there is still a mistaken routability >>>>>> problem, >>>>> but I can >>>>>> not illustrate the failure without some other case being described. >>>>>> >>>>>> Yours, >>>>>> Joel >>>>>> >>>>>>> On 10/21/14, 10:06 PM, Lizhong Jin wrote: >>>>>>> Inline, thanks. >>>>>>> >>>>>>>> -----Original Message----- >>>>>>>> From: Joel M. Halpern [mailto:jmh@xxxxxxxxxxxxxxx] >>>>>>>> Sent: 2014年10月22日 0:06 >>>>>>>> To: lizho.jin@xxxxxxxxx >>>>>>>> Cc: gen-art@xxxxxxxx; mpls@xxxxxxxx; ietf@xxxxxxxx; >>>>>>> draft-ietf-mpls-lsp-ping- >>>>>>>> relay-reply.all >>>>>>>> Subject: Re: [mpls] [Gen-art] review: >>>>>>> draft-ietf-mpls-lsp-ping-relay-reply-04 >>>>>>>> >>>>>>>> In line. >>>>>>>> >>>>>>>>> On 10/21/14, 10:36 AM, lizho.jin@xxxxxxxxx wrote: >>>>>>>>> Hi Joel, see inline below, thanks. >>>>>>>>> >>>>>>>>> Lizhong >>>>>>>>> >>>>>>>>> >>>>>>>>>> 2014.10.21，PM9:30，Joel M. Halpern <jmh@xxxxxxxxxxxxxxx> >>>> wrote ： >>>>>>>>>> >>>>>>>>>> If the process for this draft is to use the top address that can >>>>>>>>>> be reached in the routing table, then there is a significant >>>>>>>>>> probability that the original source address, which is always at >>>>>>>>>> the top of the list, will be used. As such, the intended problem >>>>>>>>>> will not be solved. >>>>>>>>> [Lizhong] let me give an example to explain: the source address A >>>>>>>>> is firstly added to the stack, then a second routable address B >>>>>>>>> for replying AS is also added. The reply node will not use address >>>>>>>>> A since it's not routable, then it will use address B. So it will >>>>>>>>> work and I don't see the problem. >>>>>>>> >>>>>>>> The whole point of this relay mechanism, as I understand it, is to >>>>>>>> cope >>>>>>> with >>>>>>>> the case when the responder X can not actually reach the source A. >>>>>>>> Now suppose that the packet arrives at X with the Address stack >>>>>>>> A, B, >>>>> ... >>>>>>> X >>>>>>>> examines the stack. The domain of A was numbered using net 10. >>>>>>>> The domain of X is numbered using net 10. A's address is probably >>>>>>> routable >>>>>>>> in X's routing table. The problem is, that routing will not get to >>>>>>>> A. X >>>>>>> examines >>>>>>>> the stack, determines that A is "routable", and sends the packet. >>>>>>>> This >>>>>>> fails to >>>>>>>> meet the goal. >>>>>>> [Lizhong] The source A you are referring is the initiator, right? >>>>>>> The goal of relay mechanism is to reach the initiator. If X is >>>>>>> routable to the initiator (address A), then it is great, other relay >>>>>>> node in the stack will be skipped. >>>>>>> If the source A you are referring is the interface address of one >>>>>>> intermediate node, then I do not understand "routing will not get to >>>>>>> A. X examines the stack, determines that A is "routable", and sends >>>>>>> the >>>>>> packet". >>>>>>> Why routing will not get to A, but A is routable? >>>>>>> >>>>>>> Regards >>>>>>> Lizhong >>>>>>> >>>>>>> >>>>>>>> >>>>>>>> Yours, >>>>>>>> Joel >>>>>>> >>>>>>> >>>>>>> >>>>> >>> > > _______________________________________________ > mpls mailing list > mpls@xxxxxxxx > https://www.ietf.org/mailman/listinfo/mpls