We need to talk about it: the wheel you refer to below might not work on all the roads... :)
For example when you go to external non-NVO3 domains you do not know all the external MAC/IP addresses so you can't program them from a centralized controller in the egress direction from NVO3. Also the non-NVO3 gateways are not controlled by the NVO3 control plane so you can't program their FIBs from the controller either. Broadcast and Multicast handling in general might require special consideration as well. A number of mechanisms can be considered to address the external network use case - see BGP MH for VPLS and/or BGP EVPN work in IETF ... It looks like we need to add access multi-homing in the framework and follow up on use cases in data and control plane requirements so that NVO3 can do a proper solution gap analysis at the end. > -----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
