Hi Tom, Thanks for the comments. The scenario discussed in the draft is: all the host traffic is encapsulated in VXLAN tunnel. So there will be no problem if the host traffic uses VXLAN port number.
-- Dapeng Liu 在 2015年7月4日 星期六，上午8:06，Tom Herbert 写道： > "The Extendable TLV field contains two TLVs. Both of them are set by > the network devices along the transport path."-- this might be > problematic. From draft-ietf-tsvwg-port-use-11.txt: "Ultimately, port > numbers numbers indicate services only to the endpoints, and any > intermediate device that assigns meaning to a value can be > incorrect.". A host may legitimately send UDP packets to the VXLAN > port number that aren't actually VXLAN, so if intermediate devices are > modifying these packets based just on destination couldn't this result > in data corruption? Magic numbers like those defined in SPUD or > https://tools.ietf.org/html/draft-herbert-udp-magic-numbers-00 could > mitigate such an issue. > > Tom > > > > > > On Fri, Jul 3, 2015 at 10:23 AM, Dapeng Liu <[email protected] > (mailto:[email protected])> wrote: > > > > > > 在 2015年7月2日 星期四，上午12:04，Dacheng Zhang 写道： > > > > HI, Shahram: > > > > Thanks for the comments. > > > > See my reply inline please.. > > > > Cheers > > > > Dacheng > > > > 发件人: Shahram Davari <[email protected] (mailto:[email protected])> > > 日期: 2015年6月30日 星期二 上午2:12 > > 至: dacheng de <[email protected] > > (mailto:[email protected])> > > 抄送: "[email protected] (mailto:[email protected])" <[email protected] > > (mailto:[email protected])>, "[email protected] > > (mailto:[email protected])" > > <[email protected] (mailto:[email protected])>, > > "[email protected] (mailto:[email protected])" > > <[email protected] > > (mailto:[email protected])>, Dapeng Liu > > <[email protected] (mailto:[email protected])> > > 主题: RE: [nvo3] Application of a time slot in this ietf meeting//Re: New > > draft: Path Detection in VXLAN Overlay Network > > > > > > > > > > > > I read your draft and I don't think it can get the information that you > > claim it does. > > > > > > > > For example you have ingress interface TLV to record the ingress port of the > > ingress PE. First of all this interface is already communicated by the > > controller to the Ingress PE. > > > > > > > > Ingress/egress interface are refer to the interfaces on the data path. The > > controller will use another interface to communicate with the PE > > > > > > > > SD> What I mean is that the controller is asking the PE to inject this test > > packet to a tunnel via a specific PE interface. So the controller already > > knows which PE interfaces the packet is going to use. > > > > > > Dacheng\ That is why For the ingress PE, only EIID is mandatory. > > > > > > > > Secondly if you want to test the Correct IP forwarding you can just use BFD > > for the outer IP. If you like to use UDP, you could do BFD over UDP over IP. > > > > BFD works at layer 2. It’s mainly used to test whether the layer 2 data path > > is connected. In contrast, our method is focusing on the tracing function. > > (Our solution can help find out which switch on the path is broken.) > > > > > > > > SD> The way you have defined it does not test anything in L2, since your > > packet is not exercising any L2 forwarding. Your packet is L3 forwarded all > > the way. > > > > > > Dacheng\ I am trying to understand your point and please correct me if I am > > wrong. The purpose of this work is to check the error of paths over a l3 > > network. (Pleas see figure 1.) > > > > > > > > Thirdly, your draft can't get the egress interface information of the egress > > PE, since there is nothing (No MAC or IP address) in your VXLAN payload that > > can be forwarded by the egress PE to the egress interface. > > > > Two TLV (IIID/EIID) could be used to record the ingress/egress interfaces ID > > of current router the OAM packet is flowing through. For the ingress PE, > > EIID is mandatory while for the egress PE IIID is mandatory. For the > > intermediate router, both IIID and EIID are mandatory. So, for the egress, > > EIID does not have to be transported to the controller. > > > > > > > > SD> I know you have TLV. But what I mean is that there is nothing in your > > draft that makes your packets to be L2 forwarded. For example you are not > > doing any (VXLAN/VNI forwarding) of your packet. As an example assume you > > packet arrives at the Final Egress PE. The Egress PE can’t forward this > > packet based on the IP destination address since it is 127/8. > > > > > > Dacheng\ Ok, our objective is to check the paths between vteps. So, the > > egress PE does not have to forward this packet to the tenant. Note we > > mentioned that for the egress PE only IIID is mandatory. > > > > > > > > Fourthly the path trace that you describe does not work. How does an > > intermediate router know it has to send a copy of this packet to CPU? The > > only method is to use TTL expiry, which already exists in IP trace route. > > > > > > > > In our method, o bit in VxLAN is used to indicate it’s a OAM packet, which > > should be copy to CPU. One OAM packet is able to trace n devices on the > > path, while TTL expire method needs n OAM packets to trace. Of course if you > > assume that the intermediate devices do not support our solution, our > > mechanism will not work properly then. > > > > > > > > SD> Are you suggesting that the intermediate routers need to do deep packet > > inspection and after finding this magical bit copy it to CPU? This is a > > layer violation and should NOT be done. You should not make decision on any > > layer when layers above it are not terminated. > > > > > > > > Basically you are expecting intermediate routers to look in to the packet, > > skip outer Ethernet, Skip IP, check IP payload is UDP, check UDP-Dest port > > is VXLAN, then check a specific bit in VXLAN header in order to decide to > > copy to CPU or not. This is architecturally wrong by any means. > > > > > > Dacheng\ Yes, we expect the intermediate routers can look into the packet. > > Our experiments have shown that this solution works very well and > > significantly reduce the complexity of detecting errors in complex networks. > > Hope other people can give us some comments on this argument. > > > > > > [Dapeng Liu] Yes. The deployment assumption in the draft is all the > > forwarding equipment should support VXLAN and this draft proposes a VXLAN > > function extension to support the OAM mechanism described in the draft. > > > > ---- > > Dapeng Liu > > > > > > > > > > > > > > Regards, > > > > Shahram > > > > > > > > > > On Jun 26, 2015, at 10:15 PM, Dacheng Zhang <[email protected] > > (mailto:[email protected])> > > wrote: > > > > Dear chairs: > > > > > > > > Can we get a time slot during the nvo3 session in Prague to discuss this > > draft? Dapeng Liu from Alibaba will be the presenter. 15 minutes would be > > good enough. > > > > > > > > Cheers > > > > > > > > Dacheng > > > > > > > > 发件人: Dapeng Liu <[email protected] (mailto:[email protected])> > > 日期: 2015年6月21日星期日上午1:04 > > 至: <[email protected] (mailto:[email protected])> > > 主题: [nvo3] New draft: Path Detection in VXLAN Overlay Network > > > > > > > > Hello all, > > > > > > > > We have submitted a draft for path detection in VXLAN overlay network. > > > > http://datatracker.ietf.org/doc/draft-pang-nvo3-vxlan-path-detection/ > > > > > > > > The draft proposes a method for path detection in VXLAN network and it > > defines the path detection packet format by using one reserve bit in the > > VXLAN header. > > > > > > > > Comments & suggestions are welcomed. > > > > > > > > > > > > -- > > > > Dapeng Liu > > > > > > > > _______________________________________________ nvo3 mailing list > > [email protected] https://www.ietf.org/mailman/listinfo/nvo3 > > > > _______________________________________________ > > nvo3 mailing list > > [email protected] (mailto:[email protected]) > > https://www.ietf.org/mailman/listinfo/nvo3 > > > > > > > > _______________________________________________ > > nvo3 mailing list > > [email protected] (mailto:[email protected]) > > https://www.ietf.org/mailman/listinfo/nvo3 > > > > >
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