How to find interface name from /sys

It would be very rare to land on a Linux box without lspci (pciutils) installed. I faced an such rare issue today while helping a friend with his lfs machine. The network will not start because the interface eth0 is missing.

We were pretty sure we have the driver since we compiled VMXNET3 (CONFIG_VMXNET3=y) into the kernel. The first thing you would naturally do is, keep reading. is run lspci to check if the device is detected. There was no lscpi as it was a bare bone lfs system.

In the absence of lspci, When you restart network or ifup an interface and it complains the interface is missing “Device ethX does not seem to be present, delaying initialization”, you have the wrong interface name.

ifconfig -a and ip a s will show you all interfaces even if they have no IP assigned. If your system is so bare bones that you don’t have net-tools or iproute2, there are other means.

 # ls /sys/class/net/
 eno16780032  lo  sit0 


# cat /proc/net/dev

It was a case of wrong interface name in the config file. Once we find the correct interface name, the fix was a matter of renaming the config file and device name inside the config file .


Deploy Nexus 1000v to ESXi to learn NX-OS commands

In this guide, we are going to deploy N1Kv virtual switch to ESXi using the ovf/ova solely for the purpose of learning NX-OS rather than what’s it made for – vSphere VM networking. Therefore, we will not be concerned with the intricate requirements for a successful N1Kv deployment for ESXi hosts.

Download the Nexus 1000V bundle from Cisco. You will need a Cisco SSO account. The bundle I download is a zip file Nexus1000v.4.2.1.SV2.1.1. It has both ova (single file) and ovf (multiple files). I used the ova because ovf didn’t work for me.

1) In vSphere client File-> Deploy OVF Template.

2) Browse to the ova file location which is in my case
Drive:\Nexus1000v.4.2.1.SV2.1.1\VSM\Install\nexus-1000v.4.2.1.SV2.1.1.ova and click Next twice.
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vNIC, vmnic naming mismatch in UCS and ESXi

I cannot get an ESXi host management network up in UCS B series blade. My friend has trouble kickstarting Linux on a different B series blade.

Check the vNIC ordering in UCS. The interface ordering in the OS usually match the vNIC ordering in UCS but not always. For instance it should be
vmnic0 = vNIC0
eth0 = vNIC0

Depending on how it was setup this is not always the case. Hence match the mac address in OS and UCS to verify. It saved my day.

ESXi portgroup missing and here’s the proof

The backup guys came over because a few Avamar Agent backup stopped working for a few Linux virtual machines. Avamar Agent backup uses a dedicated network and hence the VMs have a second interface for the agent. We checked the interface is up with ifconfig eth1 and ethtool eth1 shows it has a link. However, tcpdump -i eth1 detects zero traffic. What are we missing? Continue reading