The gateway router on your local network, if there is one, must be configured with this information, as must all hosts and switches. You must decide which router, if any, will serve as the default gateway router for your local network. This article covers how to set the default gateway on hosts and switches.
Configure the Default Gateway
To connect over the network, an end device must be configured with the proper IP address information, including the default gateway address. It uses the default gateway when the host has to send a packet to a component on a different network. The router interface address connected to the host’s local network is often the default gateway address. The host device’s IP address and the router’s interface address must belong to the same network.
Consider, for illustration, an IPv4 network topology with a router linking two distinct LANs. G0/0/1 is linked to the 192.168.11.0 network, while G0/0/0 is linked to the 192.168.10.0 network. Each host device has the proper default gateway address set up.
Imagine PC1 sending a packet to PC3 PC1 would forward the message to R1’s G0/0/0 interface as its default gateway while addressing it with PC3’s IPv4 address. The router accepts the message and, using the destination address, determines that G0/0/1 is the proper exit interface by consulting its routing table. R1 subsequently forwards the packet out of the proper interface to PC3.
On an IPv6 network, the identical procedure would take place even if this is not depicted in the topology. Devices would use the local router’s IPv6 address as their default gateway.
Gateway by default on a switch
Typically, a Layer 2 device is a switch that connects client computers. Therefore, an IP address is unnecessary for a Layer 2 switch to operate effectively. On a switch, an administrator can set up an IP configuration to provide remote access to the switch.
A switch must have a virtual switch interface (SVI) configured to be accessed and managed through a local IP network. The SVI is set up on the local LAN with an IPv4 address and subnet mask. A default gateway address must also be set up for the switch to be remotely managed from another network.
All devices interacting outside their local network normally have the default gateway address set.
Use the IP default-gateway IP-address global configuration command to set an IPv4 default gateway on a switch. The IPv4 address of the local router interface attached to the switch is the one that has been configured.
How to set Cisco Routers’ Default Routing
This lesson uses a real-world Packet Tracer example to demonstrate how to set up and use a default route in routing. Learn how to set up Cisco routers’ default routing.
A router verifies the packet’s destination network address as it arrives on one of its interfaces and locates that address in the routing table. The inbound packet is forwarded from the interface specified in the entry if the router discovers an entry for the destination network.
The router looks at the default route if it cannot locate an entry for the destination network. The router forwarded the incoming packet from the interface indicated in the default route if the default route was available.
The router drops the incoming packet if the default route is not available. All incoming packets are sent using a default route by the router even though the routing table does not contain the destination addresses.
The following circumstances typically call for adopting a default route to route each packet to a specific destination.
For logging and troubleshooting purposes, it is necessary to route all unknown packets—those whose destination network addresses are not listed in the routing table—to a server or device.
To send every packet to a device or router that can access remote networks or has a routing table with entries for every remote network.
Troubleshoot Default Gateway Problems using Packet Tracer
A device must be set up with an IP address, subnet mask, and default gateway to communicate across various networks. When the host wants to transmit a packet to a component on another network, it uses the default gateway. The router interface address connected to the local network to which the host is connected typically used as the default gateway address. You will complete the network’s documentation in this activity. After that, you will test end-to-end connectivity and conduct troubleshooting to confirm the network documentation. The steps in the troubleshooting process you will employ are as follows:
- To identify issues, check the network documentation and run tests.
- Find a suitable answer to the presented problem.
- Activate the solution.
- To make sure the issue has been fixed, test.
- Record the answer.