{{short description|Logical layer-3 interface on a multilayer network switch}} {{More footnotes|date=June 2021}}
A '''switch virtual interface''' ('''SVI''') or '''routed VLAN interface''' ('''RVI''')<ref>{{cite web|title=Understanding Routed VLAN Interfaces on EX Series Switches|url=https://www.juniper.net/techpubs/en_US/junos11.1/topics/concept/bridging-routed-vlan-interface.html|accessdate=29 May 2013}}</ref> is a virtual network interface that represents a logical layer-3 interface on a multilayer network switch.
VLANs divide broadcast domains in a local area network (LAN) environment. Whenever hosts in one VLAN need to communicate with hosts in another VLAN, the traffic must be routed between them. This is known as inter-VLAN routing. On layer-3 switches it is accomplished by the creation of layer-3 interfaces (SVIs).<ref>{{Cite web|last=Hamza|first=Arif|date=14 September 2021|title=Switch Virtual Interfaces|url=https://ciscoeducation.com/switch-virtual-interfaces-configuration/|website=Cisco Education}}</ref>
An SVI is a virtual routed interface that connects a VLAN on the device to the Layer 3 router engine on the same device. Only one VLAN interface can be associated with a VLAN, but you need to configure a VLAN interface for a VLAN only when you want to route between VLANs or to provide IP host connectivity to the device through a virtual routing and forwarding (VRF) instance that is not the management VRF. When you enable VLAN interface creation, a switch creates a VLAN interface for the default VLAN (VLAN 1) to permit remote switch administration.
SVIs are generally configured for a VLAN for the following reasons: * To allow traffic to be routed between VLANs by providing a default gateway for the VLAN. * To provide fallback bridging (if required for non-routable protocols). * To provide Layer 3 IP connectivity to the switch. * To support bridging configurations and routing protocol. * To provide an access layer - 'Routed Access' Configuration (in lieu of Spanning Tree Protocol)
Advantages include: * Much faster than router-on-a-stick, because everything is hardware-switched and -routed. * No need for external links from the switch to a router for routing. * Not limited to one link. Layer 2 EtherChannels can be used between the switches to get more bandwidth. * Latency is much lower, because it does not need to leave the switch.
==References== {{Reflist}} {{refbegin}} * Cisco Systems, [https://www.cisco.com/c/en/us/support/docs/lan-switching/inter-vlan-routing/41860-howto-L3-intervlanrouting.html Configure InterVLAN Routing on Layer 3 Switches] * Cisco Systems, [https://www.cisco.com/c/en/us/td/docs/unified_computing/ucs/ucs-director/network-devices-mgmt-guide/5-3/b_Network_Devices_Management_Guide_53/b_Network_Devices_Management_Guide_50_chapter_011100.pdf Configuring SVI] * Cisco Systems, 2006, "Building Cisco Multilayer Switched Networks" (Version 3.0), Cisco Systems Inc. * [https://ciscoeducation.com/switch-virtual-interfaces-configuration/ Switch Virtual Interfaces (SVI) configuration] * Data Centre Networking Module (COMH9003) | Cork Institute of Technology {{refend}}
Category:Computer networking
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