Switch virtual interface

As explained in Acing the CCNA Exam: Volume 2 Advanced Networking and Security

A switch virtual interface, or SVI, is a virtual Layer 3 interface on a switch that provides an IP interface for a VLAN, management, or routing.

A switch virtual interface (SVI) is a virtual Layer 3 interface associated with a VLAN. It gives a switch an IP address for management, host default-gateway service, or routing. A Layer 2 switch can send and receive IP packets through an SVI but cannot route between SVIs; a multilayer switch can route between them. section 5.2.1 section 21.1.1

Configure and verify an SVI with these Cisco IOS steps:

• Enter interface vlan vlan-id and assign an address with ip address ip-address netmask. section 5.2.1
• On a Layer 2 switch, configure ip default-gateway gateway-address so management traffic can reach remote networks. section 5.2.1
• On a multilayer switch, enable ip routing and configure an SVI for each routed VLAN. section 21.1.1
• Use show ip interface brief to verify the SVI address and up/up state; use show ip default-gateway to verify a Layer 2 switch gateway. section 5.2.1

Management SVI on a Layer 2 switch

SW1(config)# interface vlan 1 SW1(config-if)# ip address 10.0.0.2 255.255.255.0 SW1(config)# ip default-gateway 10.0.0.1 SW1(config)# do show ip interface brief Vlan1 10.0.0.2 YES manual up up SW1(config)# do show ip default-gateway 10.0.0.1 This address permits remote Telnet or SSH management; the default gateway supports management traffic outside the local subnet. section 5.2.1 section 5.4

Figure 5.3 The internal logic of Layer 2 and Layer 3 switches. The Layer 2 switch (left) can send and receive packets using its SVIs but can’t route packets between them. The Layer 3 switch (right) can send, receive, and also route packets.

Compare the internal packet-handling roles of SVIs on Layer 2 and multilayer switches. section 5.2.1

How Acing the CCNA Exam: Volume 2 Advanced Networking and Security covers it

How deep it goes

Defines behavior, configuration, verification, and the Layer 2 routing limitation without extending beyond Cisco IOS operations.

Examples

Uses VLAN 1 management configuration and management, internal, and guest SVIs on a wireless LAN switch.

What it assumes

Assumes VLAN and basic IP knowledge while distinguishing sending, receiving, forwarding, routing, and switching.

What you can do after

Operate/configure SVIs, assign addresses, set a Layer 2 default gateway, enable routing, and verify interface status.

How it connects

Connects SVIs with VLANs, Layer 2 switching, multilayer switching, inter-VLAN routing, default gateways, Telnet, and SSH.

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Also explained in

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  Acing the CCNA Exam: Volume 1 Fundamentals and ProtocolsA switch virtual interface is a virtual Layer 3 interface on a multilayer switch associated with a VLAN and configured with an IP address.

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Related concepts

• layer 3 switchused by · A Layer 3 switch is a network switch that performs both data-link-layer switching and network-layer packet routing.
• inter-vlan routingimplements · Inter-VLAN routing is the forwarding of traffic between subnets associated with different VLANs in a segmented local network.
• network switchused by · A network switch is a device that connects devices within a local network and selectively forwards data-link-layer frames to their intended destinations.
• Hot Standby Router Protocolused by · Hot Standby Router Protocol is Cisco’s first-hop redundancy protocol, which provides a resilient virtual default gateway through coordinated routers.
• vlanconfigures · A VLAN is a logically isolated Layer 2 network segment implemented within shared physical network infrastructure, typically forming a separate broadcast domain.
• dynamic interfaceequivalent to · A dynamic interface is a logical wireless LAN controller interface associated with a WLAN and VLAN and configured with network parameters and a DHCP forwarding destination.

This explainer was generated by Manning's knowledge graph from the text of Acing the CCNA Exam: Volume 2 Advanced Networking and Security. The section links point to the parts of the book it draws on.