Agree！In our scenario, it is assumed all the traffics that a intermediate router has to process are encapsulated within vxlan payloads.
发件人: Dapeng Liu <[email protected]> 日期: 2015年7月6日 星期一 下午2:35 至: Tom Herbert <[email protected]> 抄送: Shahram Davari <[email protected]>, "[email protected]" <[email protected]>, dacheng de <[email protected]> 主题: 回复： [nvo3] 回复： Application of a time slot in this ietf meeting//Re: New draft: Path Detection in VXLAN Overlay Network 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]> 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]> >> 日期: 2015年6月30日 星期二 上午2:12 >> 至: dacheng de <[email protected]> >> 抄送: "[email protected]" <[email protected]>, "[email protected]" >> <[email protected]>, "[email protected]" >> <[email protected]>, Dapeng Liu <[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]> >> 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]> >> 日期: 2015年6月21日星期日上午1:04 >> 至: <[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] >> https://www.ietf.org/mailman/listinfo/nvo3 >> >> >> >> _______________________________________________ >> nvo3 mailing list >> [email protected] >> https://www.ietf.org/mailman/listinfo/nvo3 >
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