One of the most popular networking command in Linux is the ifconfig command. It lets you see (and configure) IP address for network interface. It also shows the MAC address for each interface. The MAC address and the IP address viewing is probably the most common reason for using the ifconfig command. In addition the ifconfig command works with physical network interface (like eth0..) and virtual network interface (like Tap interface etc).
In an earlier blog, I have talked about Linux bridge based virtual networking. Recently as part of a comment on my blog, I learnt how to view and interpret the MAC table of Linux bridge. In this installment of WILT (What I Learnt Today) series, I will share how MAC Table can be used for troubleshooting Linux bridges.
In the previous blog of this series we saw that using Linux bridge we can connect a virtual Ethernet port of a VM to the physical Ethernet port of the hypervisor server. Let us now focus a bit more on these virtual ports to see what happens behind the scenes to make virtual networking actually work.
Software defined networking (SDN) is the current wave sweeping the networking industry. And one of the key enablers of SDN is virtual networking. While SDN and virtual networking are in vogue these days, the support for virtual networking is not a recent development. And Linux bridge has been the pioneer in this regard.