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 >>>>>> >>>>>> >>>>>> >>>> >>