Nexus 2248 ports for Hyper-V virtual switch uplink

Unanswered Question
Sep 30th, 2010

I'm having problems getting VMs sitting on a Hyper-V host to communicate properly. Does anyone know if there are issues with using the ports in on the Nexus 2248 and/or FEX modules in general for this purpose?  Since they are seen as a Virtual Switch in the Hyper-V host machine, I'm wondering if it is a limitation of the FEX module.

I have this problem too.
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kitanaka Mon, 10/04/2010 - 01:15


I have handy devices so tested that. I use

N2K-C2148T-1GE connected N5K-C5020P-BF-SUP NX-OS 5.0(2)N1(1)

and Win2008 server where Hyper-V is running.

I can ping from a VM to N5K SVI ip address vise versa.

Nexus & Fex Configuratin


Nexus5020-A# show run fex

!Command: show running-config fex
!Time: Tue Oct  4 07:43:35 2011

version 5.0(2)N1(1)
feature fex

fex 140
  pinning max-links 1
  description "FEX0140"

interface port-channel140
  fex associate 140

interface Ethernet1/13
  fex associate 140

Nexus5020-A# show run int e140/1/1

interface Ethernet140/1/1
  switchport access vlan 99

The VM is / 0015.5d4e.4c05. I can ping to that from Nexus5020.



Nexus5020-A# ping
PING ( 56 data bytes
64 bytes from icmp_seq=0 ttl=127 time=1.967 ms
64 bytes from icmp_seq=1 ttl=127 time=0.857 ms
64 bytes from icmp_seq=2 ttl=127 time=0.78 ms
64 bytes from icmp_seq=3 ttl=127 time=0.793 ms
64 bytes from icmp_seq=4 ttl=127 time=0.798 ms

--- ping statistics ---
5 packets transmitted, 5 packets received, 0.00% packet loss
round-trip min/avg/max = 0.78/1.039/1.967 ms

Nexus5020-A# show ip arp

IP ARP Table for context default
Total number of entries: 2
Address         Age       MAC Address     Interface      00:17:15  000d.eca2.fe3c  Vlan99     00:00:22  0015.5d4e.4c05  Vlan99

Nexus5020-A# show  mac address-table vlan 99


        * - primary entry, G - Gateway MAC, (R) - Routed MAC, O -  Overlay MAC

        age - seconds since last seen,+ - primary entry using vPC  Peer-Link

   VLAN     MAC Address      Type      age     Secure NTFY    Ports


* 99       0015.5d4e.4c05    dynamic   80         F    F  Eth140/1/1

VM (Windows 7)

Is there any configuration issue on Hyper-V side ?

Here is my VM configuration and Network Manager.

# The OS is Japanese but you can compare with yours.



JUSTIN LOUCKS Mon, 10/04/2010 - 07:52

Thanks for the reply. I did end up figuring this out. It was a VLAN turnking issues on the core layer above the 5K and not a Nexus 2K limitation. So far the Nexus 2K switches are working out fine although I think I may be done 2960S switch stacks with the 10GB uplinks from my distribution layer if I had to do it all over again for just 10/100/1000 ports. Obviously the new 2232 models with oversubscribed 10GB ports are unique to this line of devices.


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