Ivan,

I have been following this discussion for a while, think we could
avoid having IGP on the NVE in the hypervisor by changing the
transport protocol to a multipath enabled one such as SCTP/MPTCP.

By doing that no need to have an IGP/BGP on the NVE and you can
aggregate NVE IP addresses at the underlying network because the
multpath transport protocol would take care of liveness problem. If a
multi-homed NVE (e.g. two NICs to two separate ToRs) knows the remote
NVEs locators (two Nics, two ToRs) the multi-path protocol has the
possible to setup four paths to the remote NVE (Local locator
1->Remote Locator1, LL1-RL2, LL2->RL1 and LL2->RL2). The consequences
of this is that some of the traffic engineering is moved away from the
network to transport protocol, check out this study
http://www-malted.cs.ucl.ac.uk/staff/M.Handley/papers/multipath_dc_hotnets.pdf

The demarcation point between the hypervisor based NVE and the ToR
becomes simple, i.e. IP subnets and the underlying network doesn't
need to exchange much information to the NVE.

And when we get to the storage part we can maintain the air gap
between the two fabrics by leveraging SCTP/MPTCP - I'm thinking of
lossless iSCSI here and if the storage target supports multipath
transport protocol we can build SANs as we do today and maintain the
best practices.

Think it would be worthwhile to have a look on what SCTP/MPTCP can
offer, it seems that they might simplify things quite a lot.

Patrick

On Fri, Sep 7, 2012 at 8:23 PM, Ivan Pepelnjak <[email protected]> wrote:
> On 9/7/12 6:23 PM, Lucy yong wrote:
> [...]
>>
>> To use MPLS/VPN, you have a IGP network as underlay network first. If
>> NVE acts as PE. The server need to participate IGP first, the
>> loopback address of server is advertised in IGP. It does not matter
>> how many nics exist, the ecmp make it work.
>
>
> Ah, that's how it works. Thank you! Now I get it.
>
>> If the server does not run IGP protocol and act as a IP host in
>> underlay network. This seems not aligning with the nvo3 framework and
>> MPLS/VPN architecture.
>
>
> Then I sincerely apologize for wasting everyone's time and bandwidth.
>
> Thank you for your guidance,
> Ivan
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