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--- ubiquiti:vlan [2020/12/10 00:41] – peter
+++ ubiquiti:vlan [2020/12/10 01:30] (current) – [Ubiquiti - VLAN] peter
@@ Line 1: / Line 1: @@
 ====== Ubiquiti - VLAN ======
-  * Each VLAN is identified by a unique 802.1Q ID.
+VLANs (Virtual Local Area Networks), segregate traffic within a network.
-  * VLAN IDs 1 through 4094
-VLAN's and IP-intefaces:
+They allow a single physical Ethernet network to appear to be multiple logical networks.
+Benefits for using VLANs include:
+  * VLANs keep traffic from different networks separated from each other.
+  * They enhance network security by preventing wireless devices from accessing LAN resources.
+  * Increased performance by limiting broadcast domains.
+While VLAN's are effective for separating network segments and limiting broadcast traffic, it is often a requirement for subnets separated by VLAN's to be able to communicate.  This can be accomplished only through a Layer 3 enabled device that can route between the VLAN's.  Even if both VLAN's exist on a device, their traffic will be segregated unless mediated by a layer 3 routing device.
+VLAN enabled ports are generally categorized in one of two ways, tagged or untagged.
+  * VLANs can be port-based (assigning a physical port on a device to a VLAN) or tag-based (tagging particular kinds of traffic with a VLAN tag, as defined by 802.1q).
+Unifi, usually by default, have all switch ports able to consume both tagged and untagged traffic, but this can be modified.  This is known as trunking, i.e. to have a specific port enabled for VLAN tagging, and the other ports for general access.
+----
+===== Other Considerations =====
+  * For greater security, no SSID should be untagged, i.e. be on the "native VLAN".
+  * The amount of broadcast traffic on the trunk port to which an AP is attached should be limited.
+    * Limiting broadcast traffic improves wireless performance.
+----
+===== Common Terms =====
+|VLAN|Virtual Local Area Network, logical identifier for isolating a network.|
+|Trunk|A port enabled for VLAN tagging.|
+|Access|A port that does not tag and only accepts a single VLAN.|
+|Encapsulation|The process of modifying frames of data to include additional information.|
+|802.1Q|The most common encapsulation method for VLAN tagging.|
+|Native VLAN|The VLAN associated with all untagged traffic on a trunk.|
+----
+===== VLAN's and IP-intefaces =====
   * **VLAN** is a Layer 2 (L2) technology; data is sent between clients using mac-addresses.
@@ Line 10: / Line 47: @@
   * Only clients in the same VLAN and with IP-addresses in the same subnet, can send data to each other.
   * It is not possible to configure any DHCP on A VLAN, since VLAN is a L2 technology and DHCP requires an IP-interface, which is a L3 technology, so this VLAN should either be connected to an external DHCP-server or use static IP-addresses on the clients.
   * **IP-interfaces** is a Layer 3 (L3) technology; data is send between clients using IP-addresses.
+----
+===== Summary of VLANs =====
 Ubiquiti always uses **VLAN 1** as the untagged native VLAN.
+  * Each VLAN is identified by a unique 802.1Q ID.
+  * VLAN IDs are 1 through 4094.
 ----