Typical Layer 2 switches examine the destination MAC address of incoming frames and forward or flood that frame based on whether the destination MAC is in the switch's MAC table. Routing functionality is normally provided by an external router connected to the switch.
An Advanced switch with IP routing capability such as the GS724TR has the ability to look inside the Layer 2 frame at the Layer 3 IP address and route the packet internally. Having a switch route traffic internally can improve network performance, as the switch can move traffic faster internally than externally. Further, by routing inter-VLAN traffic in the switch, resources are freed up on the external router allowing the router to improve its performance. The GS724TR supports up to 32 static routes to pass traffic between VLANs.
To test this functionality, I set up two ports on two different VLANs, statically addressed PCs on each port on different subnets, and ran a ping from one PC to the other. I found the GS724TR's routing to work as advertised, and indeed I could ping from a PC in one VLAN on one subnet to a PC in a different VLAN on a different subnet without a router.
Here are the steps I followed:
Step 1: Enable Routing Mode in the IP Configuration screen. Simply click Enable on the Routing Mode radio button to turn on inter-VLAN routing.
Step 2: Create the VLANs and the virtual routing interfaces. There is a VLAN Routing Wizard which makes both tasks easy. The IP address assigned in the VLAN Routing Wizard automatically creates a virtual interface in the GS724TR that facilitates routing to that VLAN from other VLANs.
Figure 8 shows my inputs for creating VLAN 15 and its corresponding virtual interface with IP address 192.168.15.1. I repeated this step for VLAN 14.
Figure 8: VLAN Routing WizardStep 3: Configure ports to have a PVID according to their VLAN. For my test, port 14 was given a PVID of 14 and port 15 a PVID of 15.
That's all it took and I could ping from VLAN 14 to VLAN 15. To validate inter-VLAN routing, I ran a continuous ping between the PCs and enabled/disabled Routing Mode from step 1. Disabling Routing Mode killed the pings while enabling Routing Modes restored the route and pings succeeded.
The GS724TR Route Table shows the subnets and routes that are created when using the VLAN Routing Wizard. As you can see in Figure 9 under Route Status, a Next Hop IP address for each VLAN is created from the IP Address entered in the VLAN Routing Wizard in step 2. This Next Hop IP address is the gateway address I used in statically addressing each PC.
Figure 9: Route Table
VLAN support and inter-VLAN routing are some of the strengths of the GS724TR. But there are quite a few more advanced features in this switch. Port Mirroring is a powerful tool included in the GS724TR as well as the less expensive GS724T and GS724AT. I'm pointing out Port Mirroring because I ran into a surprise while testing it.
Port Mirroring allows for packet captures of traffic from a different switch port than the PC or device running the capture, a useful tool for network troubleshooting. I found when I enabled Port Mirroring to my laptop, shown below in Figure 10, Port Mirroring worked. But my PC was locked out of the switch and I could no longer access the switch to turn Port Mirroring off.
Figure 10: Port Mirroring
I notified Netgear's engineers thinking I had found a bug, but they informed it was working as intended. As stated by Netgear engineering, "this behavior is by design. The port mirroring feature on the GS724TR is to allow an administrator to monitor network traffic by attaching an external network analyzer to the destination port. The destination port no longer participates in any network protocol."
I like to use my laptop to capture and analyze packets, and the same laptop to control the switch while I'm running the capture. I suppose a dedicated device may be better for this feature in high traffic networks. But it was a bit of a nuisance to have to move the cable connected to my laptop to another switch port to turn the mirroring feature off.
Each port in the GS724TR can be individually configured with a description, speed, alarming (Link Trap), and for different frame sizes as circled in Figure 11. Jumbo frames are a favorite topic as they can improve network performance, especially in large file transfers. The GS724TR supports 1518 to 9216 byte frame sizes, configurable per port.