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New Member

Windows 2008 R2 on Cisco UCS B200M networking problems

This is driving me completely nuts.  Let me start by saying I am new to blade servers and Cisco UCS.  I did take an introduction class, and it seemed straight-forward enough.  I have a chassis with two B200M blades, on which I am trying to configure two Windows 2008 R2 servers, which I will eventually make Hyper-V servers.  This is all in a test environment, so I can do anything I want to on them.

Right now I have installed W2008 directly on hard disks on the B200M hardware.

The problem is this: even though I think I've configured the network hardware correctly, using the Cisco VIC driver software, I cannot get networking to work in any reliable way.  I cannot even get ping to work consistantly.  I can ping my local server address, but I cannot ping my gateway (HSRP address).  When I try, I get a "Reply from 10.100.1.x: Destination host unreachable (x being each particular server's last octet). I CAN, however, ping the individual IP addresses of the core switches.  I can also ping some, but not all, the other devices that share the servers' subnet.  There are no errors being generated, the arp tables  (for those devices I can ping) look good, netstat looks OK.  But I cannot get outside the local subnet...

Except when I can.

There are times when I can get all the way out to the Internet, and I can download patches from Microsoft.  When it works, it works as expected.  But if I reboot the server, oftentimes networking stops working.  Yet another reboot can get things going again.  This happens even though I've made no changes to either the UCS configs or the OS.

I cannot figure out any reason when it works at some times and not at others.  I've made sure I have a native VLAN set, I've tried pinning to specific ports on the Fabric Interconnects.  There is just no rhyme or reason to it.

Anyone know of where I can look?  I'm very familiar with Windows on stand-alone boxes (although it's no longer my area of expertise), and I manage a global WAN (BGP, OSPF, Nexus 7k, etc.) so I'm no dummy when it comes to networking, but I am utterly stumped on this one.        

Cisco Employee

Windows 2008 R2 on Cisco UCS B200M networking problems


This sounds suspeciously like a disjoint layer 2 issue. If you are running your fabric interconnects in default end host mode, do you have multiple uplinks Northnound from each FI? If possible, to troubleshoot, would you reduce the number of uplinks from each FI to one and ensure that the Northbound network (vlans) are identical to each uplink?



New Member

Windows 2008 R2 on Cisco UCS B200M networking problems

I agree, it sounds like a Layer 2 issue.  I have dual uplinks from each FI to two 5596UP switches.  I disabled one uplink on each FI as you suggested, but it did not change the situation.  I also verified the VLANs and they are identical on both the FIs and on the 5596s.

New Member

Windows 2008 R2 on Cisco UCS B200M networking problems

The problem was this: while the NICs on the blade server are called vNIC0 and vNIC1, Windows was calling vNIC1 "Local Area Connection" and vNIC0 "Local Area Connection 2".  So what I configured on UCS did not match what I was configuring in Windows.  Completely, utterly ridiculous.

Anyway, networking is working now without any issues.  Thanks for you suggestion; it did get me looking in the right direction.

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