VLAN configuration is learned by the switches. ? Stations do not belong to VLANs, packets do. ? Multiprotocol stations are put into multiple VLANs. Dest…
Overview
- What is a LAN and what is a Virtual LAN?
- Types of Virtual LANs
- IEEE 802.1Q standard
What is a LAN?
- LAN = Single broadcast domain = Subnet
- No routing between members of a LAN
- Routing required between LANs
What is a Virtual LAN
- Virtual LAN = Broadcasts and multicast goes only to the nodes in the virtual LAN
- LAN membership defined by the network manager
VLAN: Why?
- Virtual is Better than Real
o Location-independent
- Marketing LAN can be all over the building
o Users can move but not change LAN
o Traffic between LANs is routed
- Better to keep all traffic on one LAN
o Switch when you can, route when you must
- Do not VLAN over expensive WAN links
o Better security
Types of Virtual LANs
- Layer-1 VLAN = Group of Physical ports
- Layer-2 VLAN = Group of MAC addresses
- Layer-3 VLAN = IP subnet
Layer-1 VLANs
- Also known as port switching
- Can be used to provide security and isolation Does not allow user mobility.
- Moved user has a new subnet ? new IP address
? May go through a router to access the old server
Layer-2 VLANs
- LANs defined by a list of MAC addresses
- Provides full user movement
- Clients and server always on the same LAN regardless of location
- Problem: Too many addresses need to be entered and managed
Layer-2 VLANs (Cont)
- Notebook PCs change docking stations
- ? MAC address changes
- q Alternative: Membership implied by MAC protocol type field. VLAN1 = IP, VLAN2 = LAT, …
Layer-3 VLANs
- Also known as virtual subnet
- VLAN membership implied by MAC-layer protocolآ type field and subnet field 123.34.*.*
- VLAN configuration is learned by the switches
- Stations do not belong to VLANs, packets do.
- Multiprotocol stations are put into multiple VLANs
Higher Layer VLANs
Different VLANs for different applications:
o FTP
o Multimedia
Service based VLANs: All workstations using Email server are on the EMAIL-VLAN, all workstations using employee database sever are on the HR-VLAN,..
IP Multicast address based VLANs
General policy based: VLAN membership can be based on a combination of incoming port, MAC address, subnet, or higher layer info, time of day.
Virtual LANs.pdf