Peter: > -----Original Message----- > From: Peter Psenak [mailto:ppse...@cisco.com] > Sent: Friday, August 5, 2022 1:55 PM > To: Huzhibo <huzh...@huawei.com> > Cc: lsr@ietf.org > Subject: Re: Question about draft-ppsenak-lsr-igp-ureach-prefix-announce > > Zhibo, > > On 03/08/2022 21:09, Huzhibo wrote: > > Hi Peter: > > Please see inline. > > > >> -----Original Message----- > >> From: Peter Psenak [mailto:ppse...@cisco.com] > >> Sent: Wednesday, August 3, 2022 11:20 PM > >> To: Huzhibo <huzh...@huawei.com> > >> Cc: lsr@ietf.org > >> Subject: Re: Question about > >> draft-ppsenak-lsr-igp-ureach-prefix-announce > >> > >> Hi Zhibo, > >> > >> On 29/07/2022 20:49, Huzhibo wrote: > >>> Hi Peter: > >>> > >>> Supplement to yesterday's online questions, If a node that does not > >>> support IP Flexalgo, which has a default route, should the node > >>> process the IP Flexalgo prefix as a UPA? > >> > >> - I assume you are talking about the algo 0 default route. Because IP > >> Flex-algo default route does not make much sense really. > >> > >> - If the node does not support IP flex-algo, than it would not use > >> any IP algo prefix as BGP service endpoint or for any other purpose. > >> > > > > Which IP Algo prefix as BGP service endpoint is not determined by the > > ingress > node, Such as VXLAN and SRv6 VPN. > > When the ingress node receives an BGP Service cayyied a IP algo prefix > > as endpoint and it has a algo 0 default route, it should be process this BGP > service. and this can not be affected by the IGP Flexalgo prefix. > > sorry, but above is completely wrong. > > When you want to use IP flex-algo forwarding, you must advertise the prefix as > algo prefix, relying on the algo 0 default would not give you algo forwarding. > > Advertising IP algo prefix at the egress and relying in algo 0 default at the > ingress is going to cause all sorts of problems. You CAN NOT mix/change algos > along the path through the network - if you do, you may end up in a permanent > loop. If the ingress node does not support Flexalgo, the ingress node does not cause a permanent loop because once the packet is forwarded to the Flexalgo node, it always follows Flexalgo forwarding. If the packet does not reach the Flexalgo node, it always follows Algo 0 forwarding.
> > > Therefore, > > the IGP does only not generate the RIB/Fib for LSinfinity Metric prefix, > > but can > not trigger BGP Service Down. > > In addition, LSinfinity Metric may be applied to other scenarios in > > the future. We cannot guarantee that LSinfinity Metric will not conflict > > with > other purposes when being processed as a UPA. > > no, it can not, because the LSinfinity has a very strict definition - it means > unreachable, which is exactly what the UPA is about. > I believe you are confusing a concept. The LSInfinity metric defined in RFC 5308 can be considered as zero route, but PUA/UPA actually defines a negative route. It's not consistent > Peter > > > > >> - If such node receives the IP algo prefix and even if it treats it > >> as UPA, given that such IP algo prefix was never reachable before on > >> this node, the UPA would result in no action. > >> > >> thanks, > >> Peter > >>> > >>> Thanks > >>> > >>> Zhibo > >>> > >> > > > > > _______________________________________________ Lsr mailing list Lsr@ietf.org https://www.ietf.org/mailman/listinfo/lsr
