VLANs

For a device designed to support a small network, the RVL200 has VLAN functionality that could support a much larger network, with capability to support 253 devices over 16 VLANs. The RVL200 has options to support not only port-based VLAN capability, but also logical VLAN separation and 802.1q trunking. 

Logical VLAN separation means using separate subnets for each VLAN. We posted a How To article earlier this year on creating VLANs using port-based technology to separate devices in the same subnet. The RVL200 allows separate subnets for each VLAN, assigning an IP in each subnet as a virtual LAN interface, and routing between each subnet.

Other recently tested routers support multiple subnets on the LAN interface, but allow Layer 2 broadcasts to propagate across subnets. The RVL200 VLAN capability allows multiple subnets on the LAN interface, but does not allow Layer 2 broadcasts to propagate across subnets.

For VLAN configuration, the RVL200 supports three port modes called Trunk, General, and Access. Trunk port mode utilizes the 802.1q VLAN standard to tag all frames, except those from VLAN1, with a VLAN identifier. This mode is useful on ports connecting the RVL200 and a smart switch that supports 802.1q trunking. General port mode allows ports to be members of multiple VLANs, while Access port mode is useful to configure ports as a member of a single VLAN.

Configuring VLANs is done by adding the numerical VLANs, either individually or by range. Once the VLAN numbers are added, a name can be added and ports can be assigned using the radio buttons shown in Figure 7.

Figure 7: VLAN membership configuration

The RVL200 DHCP server also has configuration options to automatically assign IP addresses in different subnets based on VLAN. This feature is useful, as it makes having multiple VLANs with different subnets more manageable. Take a look at Figure 8 below. I've configured the RVL to use 192.168.3.0 /24 for VLAN1 and 192.168.1.0 /24 for VLAN2.

Figure 8: VLAN DHCP configuration with multiple subnets

I had some intermittent performance on this feature. Initially, the DHCP server didn't provide IP addresses to clients on ports assigned to VLANs other than VLAN1. However, after some trial and error and without changing the configuration, the DHCP server on VLAN2 started working. I'm never comfortable when things don't perform as expected and then start working without explanation. But I was glad to see this feature work.

To net out the VLAN capabilities, the RVL200 provides full VLAN separation at both Layer 2 and Layer 3, with Layer 2 broadcasts being confined to each VLAN. 

QoS

In a perfect world, a network has twice the amount of bandwidth it can use. In the real world, we have to optimize our networks to make the most of the available bandwidth. Many network devices support Quality of Service (QoS) configurations to prioritize traffic flows and give preference to delay and drop sensitive packets.

The Linksys RVL200 has two options for managing bandwidth utilization, plus the ability to prioritize traffic queues based on Class of Service (CoS) and Differentiated Services Code Point (DSCP) markings.

To begin, I configured the upstream and downstream bandwidth of my ISP connection and chose a bandwidth management scheme based on Rate Control or Prioritization. Rate Control allows for defining a minimum and maximum amount of bandwidth, assigning that bandwidth to a specific traffic type based on TCP/UDP port and IP address, and then specifying whether to apply it to an incoming or outgoing data flow.

Prioritization is accomplished by assigning High or Low to a specific traffic type, by direction. A selection of High priority will allocate 60% of the bandwidth to that traffic, while a selection of Low priority will allocate 10% of the bandwidth to that traffic. The Linksys manual indicates traffic can also be assigned a priority of Medium, but that option wasn't available in the drop-down, as shown in Figure 9.

Figure 9: Bandwidth management and QoS settings

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