RE: Nexus 5K vPC Peer link 1Gb over OM2 Fiber

It actually does appear to be supported. Below are two 5Ks running 5.1(3)N1(1a) that allow this config:

N5K2# sh ver | in system:
  system: version 5.1(3)N1(1a)
  
N5K2# show vpc
Legend:
                (*) - local vPC is down, forwarding via vPC peer-link

vPC domain id : 1
Peer status : peer adjacency formed ok
vPC keep-alive status : peer is alive
Configuration consistency status: success
Per-vlan consistency status : success
Type-2 consistency status : success
vPC role : secondary
Number of vPCs configured : 1
Peer Gateway : Disabled
Dual-active excluded VLANs : -
Graceful Consistency Check : Enabled

vPC Peer-link status
---------------------------------------------------------------------
id Port Status Active vlans
-- ---- ------ --------------------------------------------------
1 Po1 up 1,10

N5K2# show port-channel summary
Flags: D - Down P - Up in port-channel (members)
        I - Individual H - Hot-standby (LACP only)
        s - Suspended r - Module-removed
        S - Switched R - Routed
        U - Up (port-channel)
        M - Not in use. Min-links not met
--------------------------------------------------------------------------------
Group Port- Type Protocol Member Ports
      Channel
--------------------------------------------------------------------------------
1 Po1(SU) Eth LACP Eth1/15(P) Eth1/16(P)
12 Po12(SU) Eth LACP Eth1/8(P) Eth1/9(P)

N5K2# show int e1/15 - 16 status

--------------------------------------------------------------------------------
Port Name Status Vlan Duplex Speed Type
--------------------------------------------------------------------------------
Eth1/15 -- connected trunk full 1000 SFP-1000BAS
Eth1/16 -- connected trunk full 1000 SFP-1000BAS

Also it says that this should trigger a compatibility-parameter mismatch for the port-channel, but it's not actually triggering it:

N5K2# show port-channel compatibility-parameters | in peer-link
* 1G port is not capable of acting as peer-link
Members must be 10G to become part of a vPC peer-link.

Should you do this though? Probably not. Like Mark said there are certain failure scenarios that can cause the vPC to melt down. Also if you are running Multicast, the Peer-Link *will* be used in the data plane.

This also begs another question though, why are the switches so far apart physically? Are you dual homing the servers to them with 600 foot cable runs?

Brian McGahan, CCIE #8593 (R&S/SP/Security), CCDE #2013::13
bmcgahan_at_INE.com
 
Internetwork Expert, Inc.
http://www.INE.com

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of marc edwards
Sent: Thursday, April 04, 2013 2:52 PM
To: Ryan West
Cc: Ian.blaney; ccielab_at_groupstudy.com
Subject: Re: Nexus 5K vPC Peer link 1Gb over OM2 Fiber

I see CCIE as a way to optimize designs made by people who don't have much sense ;) I

So sounds like the 1G won't work at all. I would also agree that trying to push 10G past the distance limitations of the physical media is also very risky.

Might want to call out the cable contractor and put in some OM4. You can use the OM2 as a pull string.

Regards,

Marc

Marc Edwards
CCIE #38259

On Thu, Apr 4, 2013 at 12:45 PM, Ryan West <rwest_at_zyedge.com> wrote:

> On Thu, Apr 04, 2013 at 15:26:25, marc edwards wrote:
> > Subject: Re: Nexus 5K vPC Peer link 1Gb over OM2 Fiber
> >
> > I would agree that vPC doesn't forward much data under normal
> > circumstances... But what about forwarding mechanism in failure
> scenarios?
> > If not addressing these during design, then one learns the hard way
> > if the unfortunate situation happens. (ie switch failure down stream
> > on chassis one causing forwarding only on chassis 2 but also a link
> > failure on chassis two upstream to router)
> >
> > The whole concept of multi chassis solutions is to provide HA in
> > failure scenarios which won't interrupt or cause severe limitations
> > to data forwarding. If not setting up the vPC peer link for such
> > scenarios, than why go with a multi chassis solution at all?
> >
>
> Planning for failures, that's crazy talk. The CCIE is all about
> designing stuff that doesn't make much sense. I've carried that into
> the real world
> :)
>
> If you re-read what I wrote, I wasn't defending running it at 1G, I
> was just saying that under normal circumstances there should be little
> to no traffic across it. You have a design issue if there is. I also
> mentioned that I create mine using two links, a design recommendation.
> Offhand, I wasn't sure if it would form over 1G, but checked and found
> that it will throw an error.
>
> I would venture to say that more problems come from Layer 3 VPC, than
> would arise from the choke of a 1G connection as a VPC peer link.
> Just throw a management port of a Netapp in the mix and watch the fun
> begin. I would like to see some of the limitations of the peer link
> relaxed if layer
> 3 is involved. After all, I'm burning 20Gbps worth of ports on both
> devices for a failure that might happen once in the next 5 years.
>
> -ryan

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Received on Thu Apr 04 2013 - 15:27:56 ART