Hi Ivan, Snip..
On the other hand, LISP defines several mechanisms that can be used to check the ETR liveliness. [[LY]] LISP provides a control plane function. If an ETR is not live, it needs to update all the end systems attaching to that ETR as "deleted". So no packet should be forwarded to the end systems behind ETR. Coming back to nvo3, we'll have serious problems with NVE in a hypervisor using more than one underlay IP address, more so if its control-plane session uses only one of them. We'll never know whether the other IP addresses are reachable (the problem becomes worse if you have a DC transport infrastructure that's a mixture of L2 and L3). [[LY]] IMO: an overly network has to "believe" that underlying network is able to reach the remote NVE. Without such "believe", the architecture will not work. ETR live does not mean the intermediate nodes or links in underlying network being live. Overlay tunnel is to rely on the underlying network transport. Should underlying network report its transport status to an overlay? This is an very old problem in the layered transport network. It is option, not required because of the scalability. In situation where NVE has more than one IP address used by nvo3, we need (in my opinion) something that checks the liveliness of the remote NVE IP address ... and it's not an implementation detail, it's a mandatory requirement. [[LY]] I think this is different aspect. If NVE is dead, neither IP address can help to reach the end system behind it. In fact, a sender should not send a packet to a dead NVE. Lucy Hope this makes more sense Ivan > -----Original Message----- > From: Balus, Florin Stelian (Florin) [mailto:florin.balus@alcatel- > lucent.com] > Sent: Tuesday, September 04, 2012 11:46 PM > To: Ivan Pepelnjak > Cc: Somesh Gupta; [email protected] > Subject: RE: [nvo3] Support for multi-homed NVEs > > Ivan, > See in-line... > > > -----Original Message----- > > From: Ivan Pepelnjak [mailto:[email protected]] > > Sent: Tuesday, September 04, 2012 12:03 PM > > To: Balus, Florin Stelian (Florin) > > Cc: Somesh Gupta; [email protected] > > Subject: Re: [nvo3] Support for multi-homed NVEs > > > > A) Not per prefix (at least not without serious amount of end-to-end > > BGP multipathing+BGP AddPath or multiple RDs) > > > > B) There's no liveliness check in *VPN (apart from LISP) > [FB>] How are the VPN specifications (IP VPN, VPLS, VPWS or incoming EVPN) > connected to LISP? Also can you be more specific on the absence of > liveliness check in *VPN. Are you talking about a certain > deployment/implementation environment? > Thanks, > Florin > > > > > In MPLS/VPN we rely on the host route to PE loopback and/or LSP to the > > /32 prefix to indicate next hop validity. That won't work for > > hypervisor-based NVEs > > > > On 9/4/12 8:00 PM, Balus, Florin Stelian (Florin) wrote: > > > AFAIK the text in NVO3 framework and requirements drafts allows > > multiple IPs per NVE. We have multiple IPs per PE in current VPN > > implementations. This is an implementation matter though in my opinion. > > > > > >> -----Original Message----- > > >> From: Somesh Gupta [mailto:[email protected]] > > >> Sent: Tuesday, September 04, 2012 10:51 AM > > >> To: Ivan Pepelnjak; Balus, Florin Stelian (Florin) > > >> Cc: [email protected] > > >> Subject: RE: [nvo3] Support for multi-homed NVEs > > >> > > >> Florin, > > >> > > >> Regarding the multi-homing, my assumption is that the NVE in the > > >> hypervisor would not (want to) run a routing protocol. So as Ivan > > >> points out, the standard would need to accommodate multiple IP > > >> addresses per NVE. > > >> > > >> Somesh > > >> > > >>> -----Original Message----- > > >>> From: Ivan Pepelnjak [mailto:[email protected]] > > >>> Sent: Tuesday, September 04, 2012 9:58 AM > > >>> To: Balus, Florin Stelian (Florin) > > >>> Cc: Somesh Gupta; [email protected] > > >>> Subject: Re: [nvo3] Support for multi-homed NVEs > > >>> > > >>> Ah, that other can of worms ;) Mine was simpler. > > >>> > > >>> On the underlay side, we might decide that NVEs have a single IP > > >>> address or multiple IP addresses (like some NVGRE load balancing > > >>> proposals). If we decide NVEs have a single IP address (potential > > >>> per virtual network segment), then the rest is implementation > > >>> details > > >> (and > > >>> we're back to MLAG/SMLT land for true redundancy). Alternatively > > >>> we might implement the option of having multiple IP addresses per > > >>> NVE, and the NVEs might use the IP-address-per-link option (thus > > >>> no need for L2 or MLAG at all). > > >>> > > >>> On the overlay side, the real problem (as you stated) is the > > >>> multi-homing of NVO3-to-legacy gateways. I don't see any other > > >>> need for overlay NVE multihoming. > > >>> > > >>> BTW, Nicira has nicely solved the NVO3 gateway multihoming - the > > >> whole > > >>> NVO3 network works exactly like VMware's vSwitch: split horizon > > >>> bridging (thus no forwarding loops through NVO3), with every VM > > >>> MAC address being dynamically assigned to one of the gateways, > > >>> which also solves the return path issues (dynamic MAC learning in > > >>> legacy network takes care of that). Maybe we should just use the > > >>> wheel > > that > > >>> has already been invented? > > >>> > > >>> Kind regards, > > >>> Ivan > > >>> > > >>> On 9/4/12 6:45 PM, Balus, Florin Stelian (Florin) wrote: > > >>>> I understand the discussion below is about the NVE multi-homing > > >>> towards the IP core, on the tunnel side. > > >>>> We did not focus in the framework draft on the core redundancy as > > >> in > > >>> our opinion there was no need to standardize anything here. There > > >>> are no differences from what is available today in regular IP > > networks: > > >> if > > >>> NVEs are multi-homed directly to the next IP router, regular > > routing > > >>> will take care of it. If there is Ethernet switching in between > > >>> NVE and the next IP hop, L2 resiliency mechanisms need to be > employed. > > >>> From what I read below it looks more of an implementation > > >>> discussion than a standardization requirement. Am I right? > > >>>> By Multi-homed NVEs one can also understand a set of NVEs > > >>>> multi-homed > > >>> on the access side to other devices. That is a discussion we need > > to > > >>> have in my opinion. An use case example: NVO3 network - NVE GWs > > >> multi- > > >>> homed to external non-NVO3 networks. Handoff can be VLANs, VPLS > > PWs, > > >>> or BGP EVPN labels... > > >>>> I think the latter is worth discussing although there are some > > >>> mechanisms and some standardization initiatives in place already. > > >>>> > > >>>>> -----Original Message----- > > >>>>> From: [email protected] [mailto:[email protected]] On > > >>>>> Behalf > > >>> Of > > >>>>> Ivan Pepelnjak > > >>>>> Sent: Friday, August 31, 2012 12:23 AM > > >>>>> To: 'Somesh Gupta'; [email protected] > > >>>>> Subject: Re: [nvo3] Support for multi-homed NVEs > > >>>>> > > >>>>> This is definitely an interesting can of worms ;) > > >>>>> > > >>>>> While I don't think we should go down the path of IP-A/IP-B > > >>>>> networks similar to some other DC technology, we will face the > > >>>>> reality of > > >>> some > > >>>>> NVE elements (hypervisor soft switches) not being underlay IP > > >>> routers. > > >>>>> We could either: > > >>>>> > > >>>>> (A) ignore the issue and expect the network designer to solve it > > >>> using > > >>>>> any one of the existing NIC teaming/MLAG kludges while retaining > > a > > >>>>> single encapsulation IP address per NVE; > > >>>>> > > >>>>> (B) provide support for multiple encapsulation addresses per NVE > > >> so > > >>> a > > >>>>> multi-homed NVE could have one IP address per physical interface > > >>>>> and send and receive nvo3-encapsulated frames using more than > > >>>>> one > > >>> address. > > >>>>> Option (A) is the easy way out similar to existing MPLS/VPN > > >>>>> behavior and would fit well with existing DC deployments. It > > would > > >>>>> also > > >>> retain > > >>>>> all the server-to-ToR multihoming complexity. > > >>>>> > > >>>>> Option (B) would reduce the complexity of the underlay DC > > >>>>> network (which would become a simple L3 network with > > >>>>> single-homed IP addresses), but we'd have to deal with a bunch > > >>>>> of additional > > >>> problems > > >>>>> (peer IP address liveliness check). > > >>>>> > > >>>>> Just speculating ... > > >>>>> Ivan > > >>>>> > > >>>>>> -----Original Message----- > > >>>>>> From: [email protected] [mailto:[email protected]] On > > >>> Behalf > > >>>>>> Of Somesh Gupta > > >>>>>> Sent: Friday, August 31, 2012 6:58 AM > > >>>>>> To: [email protected] > > >>>>>> Subject: [nvo3] Support for multi-homed NVEs > > >>>>>> > > >>>>>> I did not see any mention of multi-homed NVEs in > > >>>>>> draft-lasserre- > > >>> nvo3- > > >>>>>> framework-03.txt. NVEs are connected together by an L3 network > > >>>>>> - > > >>> does > > >>>>>> that mean only one? > > >>>>>> Can it be multi-homes to two L3 networks? > > >>>>>> > > >>>>>> Somesh > > >>>>>> _______________________________________________ > > >>>>>> 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 _______________________________________________ nvo3 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nvo3
