[c-nsp] Nexus 5k dual sup design

[manderson]

Thanks JP.  The newer code allows LAG A/A.  To your last point we'll be
testing Config-Sync next week.


On Sun, May 26, 2013 at 8:13 AM, JP Velders <jpv at veldersjes.net> wrote:

>
> > Date: Thu, 23 May 2013 08:44:36 -0700
> > From: manderson <chiefwfb at gmail.com>
> > Subject: [c-nsp] Nexus 5k dual sup design
>
> > Hello, we currently use a single sup design in one of our DC's and we're
> > playing w/a dual sup design for single homed servers in our other DC.
> >  Cisco A/S, our SE, and myself are not particularly fond of the dual sup
> > design.  However, the lead engineer appears to be set on going this
> route.
>
> > Other than having two different architectures at two different DC's, and
> > designing a network to support single homed servers, I'm looking for
> > additional pros/cons as points of discussion.
>
> Dual-homing FEX'es allows for lower impact on upgrades (and has been a
> saver before, given that weird stuff happens on NXOS).
>
> However, a dual-homed FEX does _not_ allow for LAGs downstream (to
> dual home a server in active/active mode), at least on the 1st gen
> FEXes we have, and that stupidity (together with all the STP
> limitations) has steered me away from N2/5K for real datacenters.
>
> Do make sure to look at any vPC setup with an almost pessimistic view
> to work out all the failure scenarios and design accordingly.
>
> Also remember that in a dual-homed FEX setup you need to duplicate
> everything on both N5K's, and inconsistencies can be impacting.
>
> Kind regards,
> JP Velders
>