by: Linux/Unix Networking

On-prem servers must deal with challenges that cloud providers handle behind the scenes.

  • Network Bridge
    • Makes Linux work as a layer 2 switch, forwarding frames based on a local ARP table per interface.
  • Link Aggregation
    • Combines multiple network interfaces into a single interface for increased throughput and hardware fault tolerance.
  • VLAN
    • A Linux server can route traffic between multiple VLANs or serve across multiple sub-networks.

NETWORK BRIDGE

sudo apt install bridge-utils -y
sudo brctl addbr br0
sudo brctl addif br0 eth0 eth1
ip addr show

Configuring bridging using /etc/network/interfaces:

# Set up interfaces manually:
iface eth0 inet manual
iface eth1 inet manual

# Set up the bridge interface:
iface br0 inet static
    bridge_ports eth0 eth1
    bridge-stp off
    bridge-fd 0
    address 192.168.1.2
    broadcast 192.168.1.255
    netmask 255.255.255.0
    gateway 192.168.1.1

Additional options that may apply to your setup:

  • bridge_stp off
    • Disable Spanning Tree Protocol
  • bridge_waitport 0
    • No delay before a port becomes available
  • bridge_fd 0
    • No forwarding delay
  • bridge_ports regex eth*
    • Match ports using a regular expression

LINK AGGREGATION

Configuring LACP using /etc/network/interfaces:

sudo apt install ifenslave -y
echo "bonding" | sudo tee -a /etc/modules
modprobe bonding
sudo nano /etc/network/interfaces
auto bond0
iface bond0 inet static
    address 192.168.1.101
    netmask 255.255.255.0
    gateway 192.168.1.1
    dns-nameservers 192.168.1.1
    bond-mode 802.3ad
    bond-miimon 100
    bond-lacp-rate fast
    bond-slave eth0 eth1
    bond-downdelay 200
    bond-updelay 200
    bond-lacp-rate 1
    bond-xmit-hash-policy layer2+3

allow-hotplug eth0
auto eth0
iface eth0 inet manual

allow-hotplug eth1
auto eth1
iface eth1 inet manual
sudo systemctl restart networking
cat /proc/net/bonding/bond0

Configuring LACP bonding using Netplan:

network:
 version: 2
 renderer: networkd
 ethernets:
   eports:
     match: 
       name: eth*
 bonds:
   bond0:
     interfaces: [eports]
     addresses: [10.0.0.1/24]
     gateway4: 10.0.0.1
     nameservers:
       search: [domain.local]
       addresses: [8.8.8.8]
     parameters:
       mode: 802.3ad
       lacp-rate: fast
       mii-monitor-interval: 100

Apply the configuration:

netplan status --diff --all
sudo netplan apply
cat /proc/net/bonding/bond0

VLAN

Configure a VLAN via the command line (non-persistent):

sudo apt install vlan
modprobe --first-time 8021q
modinfo 8021q
sudo ip link add link eth0 name eth0.100 type vlan id 100
sudo ip addr add 192.168.1.2/24 dev eth0.100

Configure a VLAN using Netplan.

Edit the relevant file(s) in /etc/netplan/:

network:
  ethernets:
    eth0:
      dhcp4: true
    vlans:
        eth0.100:
            id: 100
            link: eth0
            addresses: [192.168.10.10/24]

Then restart the network service:

sudo systemctl restart systemd-networkd

Configure a VLAN using ifconfig:

sudo apt install net-tools -y

Add the following to /etc/network/interfaces:

auto eth0.100
iface eth0.100 inet static
address 192.168.10.10
netmask 255.255.255.0
vlan-raw-device eth0.100

Then bring the interface up:

sudo ifconfig eth0.100 up