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--- ubiquiti:vlan [2020/12/09 23:43] – peter
+++ ubiquiti:vlan [2020/12/10 01:30] (current) – [Ubiquiti - VLAN] peter
@@ Line 1: / Line 1: @@
 ====== Ubiquiti - VLAN ======
-[[Ubiquiti:VLAN]]
+VLANs (Virtual Local Area Networks), segregate traffic within a network.
+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.
+  * VLANs limits broadcast/flooding a domain.
+  * 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.
+----
+[[Ubiquiti:VLAN:Trunk Port|Trunk Port]]
 ----
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   * **Corporate** is a general purpose network and by default is assigned to LAN.
     * The UniFi controller will provision not only the VLAN itself but also a matching IP subnet for this VLAN.
+    * Clients associated to the VLAN uses the IP-interface as a default gateway to reach anything outside the VLAN, like other hosts on other VLAN's, the internet and so on.
+    * On this VLAN it's possible to configure a DHCP-server locally on the switch to provide IP-addresses to clients.
     * IP subnets exist at Layer 3, whereas UniFi switches are purely Layer 2.
     * Therefore, if you have no USG, there's no point in creating a "Corporate" VLAN.
   * **Guest** will apply the Guest Control setting if you enable the Guest Portal.
   * **VLAN Only** will remove any subnet options and can be used to define VLANs for pure VLAN tagging purposes by Unifi switches.
+    * This allows you to add/remove a VLAN tag to network packets on a switch port (for instance) connected to another, non-Unifi network device that expects/sends these.
+    * It is not possible to configure any DHCP on this, 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.
     * This is the best choice to use for a VLAN, if not using a USG.