1. VLANs in
Red Hat Enterprise Linux
Raghu Udiyar
Technical support engineer
Red Hat
1 VLANs & you | Raghu Udiyar
2. First, LAN?
● Local Area Network
● Uses Ethernet for Layer 2 communication
● using MAC addresses
● ARP is used for IP -> MAC
● ARP uses broadcast
● LAN = 1 Broadcast domain
● A short refresher on how this works
2 VLANs & you | Raghu Udiyar
3. Port 1 A : f3:a3:34:
Port 2 B : f2:de:34:
This mac is D
Port 3 C : f1:d1:23
On port 4
Port 4 D : f3:a4:56
Who is 192.x.x.x Hey, that's me
Mac is f3:a4:x:x:x
3 VLANs & you | Raghu Udiyar
4. To recap
● A–B–C–D
● A -> D
● ARP broadcast, D is IP 192.x.x.x what is MAC?
● D replies with MAC
● A sends to switch
● Switch looks up the address in the MAC table
● Switch sends to D
4 VLANs & you | Raghu Udiyar
6. VLANs
● Splits a LAN into multiple LANs
● Into multiple broadcast domains
● Splits single switch into multiple switches
6 VLANs & you | Raghu Udiyar
7. Port 1 A : f3:a3:34:
Port 2 B : f2:de:34:
Port 3 C : f1:d1:23
Port 4 D : f3:a4:56
B
Trunk
B
B
B B
7 VLANs & you | Raghu Udiyar
15. Use case 1 :
SW1
Httpd
Payroll
eth0.40
eth0
SW2
15 VLANs & you | Raghu Udiyar
16. Use Case 2 :
Hypervisor with two guests
VM1 VM2
VLAN10 VLAN20
eth0
Trunk
16 VLANs & you | Raghu Udiyar
17. Demo - Assigning a Vlan ID
● # vconfig add eth0 7
● # ip addr add dev eth0.7 192.168.0.1/24 brd +
● # ip link set dev eth0.7 up
17 VLANs & you | Raghu Udiyar