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
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