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Dual WAN VPN Router
At a glance
ProductCisco Dual WAN VPN Router (RV042 v3)   [Website]
SummaryNew version of popular Cisco small-business VPN router
Pros• Flexible Dual WAN ports
• Dual-stack IPv6 support
• Up and downlink priority and bandwidth QoS
• 50 IPsec tunnels
• Subscription content filtering option
Cons• 10/100 vs. Gigabit ports
• Admin access problem with Firefox / Windows

Typical Price: $0  Buy From Amazon


Updated 6/23/2011: Clarified port forwarding features

We first reviewed the Linksys RV042 back in 2007.  Four years later, the Linksys branding is gone and the device is now the Cisco RV042 and in its third hardware revision. In fact, Cisco has changed processors and increased memory across its RV0XX line, hence this new look at the RV042 "v3".

The RV042 is still the little brother to the RV082 and RV016.  They all still have 10/100 ports, both on the LAN and WAN, the difference being in the total number of LAN and WAN ports.  The RV042 has 4 LAN, 1 WAN, and 1 WAN/DMZ port.  The RV082 has 8 LAN, 1 WAN, and 1 WAN/DMZ port.  The RV016 has 16 total ports, of which 8 are LAN, 5 can be LAN or WAN,  2 are WAN, and 1 WAN/DMZ port. 

Physically, the RV042 is pretty much the same.  It is still 5.1” across the front, 7.9” from front to back, and 1.5” high.  In back of the RV042 are the WAN and LAN ports, as well as a recessed reset button.  The front of the device has the indicator lights.  Both the rear and front are shown below.

RV042 front and rear panels

Figure 1: RV042 front and rear panels

The power connector is on the side of the RV042.  There is no cooling fan, so it runs quiet.  It has rubber feet for placing on a desk, as well as holes on the bottom for wall mounting.


As described in the New to the Charts article, the RV042 is powered by a 300 MHz Cavium CN5010, replacing the Intel IXP425-266 in the V1. RAM and flash have been bumped up to 128 MB and 32 MB, respectively, up from 32 MB and 8 MB in the original RV042. A Realtek RTL8309G switch rounds out the list of major components.

Figure 2: RV042 board

In Use

For 2011, the look and feel of the RV042's menu has been updated, but remains intuitive and easy to navigate.  There are 10 main menus on the left side of the screen, each with 1-11 sub-menus. Figure 3 provides a glimpse of the new Admin GUI.

RV042 v3 admin interface

Figure 3: RV042 v3 admin interface

You configure the RV042 via a browser, but there is a known problem with Firefox.  I had no trouble with IE8 and Safari connecting to the RV042, but the configuration pages were not completely displayed using Firefox on Windows.  Cisco told me this is a known issue and they have resolved it in the next firmware release.  I was able to use Firefox with the RV042 on a Linux machine without issue.

My 2007 review described support for multiple LAN subnets, which remains a feature in the v3.  This feature allows you to use different subnets on your LAN, a useful and simple way to segment a small network. 

The RV042 supports up to 4 port-based VLANs, but doesn't support 802.1q VLANs.  Port-based VLANS allows you to separate traffic by physical LAN port on the RV042, although all devices will be on the same subnet.

Dynamic DNS can be configured on both WAN ports.  I had no problem configuring a Dynamic DNS account on WAN1.  Dynamic DNS is a very useful service, especially if you don't have static IP addresses from your ISP.

The RV042 supports RIPv1 and RIPv2 for IPv4 dynamic routing and RIPng for IPv6 dynamic routing.  Static routes can also be added to direct traffic to specific next hop IP addresses.  If the RV042 isn't being used as a Gateway router to your ISP, it can be configured in Router mode, which disables NAT functionality on the router.

The RV042 supports multiple other networking protocols, including Universal Plug and Play (UPnP), Apple's Discovery-Bonjour service, One-to-One NAT, and SNMP.  IPv6 is a new networking feature in the 2011 RV042, which deserves its own section.


IPv6 support in the RV042 was introduced in firmware  The manual for the RV042 hasn't kept up with the firmware, though, because it lacks documentation on the RV042's IPv6 features.

I recently reviewed the Cisco RV220W, which has extensive IPv6 support.  The RV042 has fewer IPv6 options than the RV220W, and thankfully doesn't require a reboot to enable or disable IPv6 as the RV220W does.  The RV042 can run IPv4 only, or Dual-Stack IPv4/IPv6 mode.

Dual-Stack enables the router to support IPv4 addressing and IPv6 addressing, as shown in Figure 4.

IP mode selection

Figure 4: IP mode selection
Note: A quick word about IPv6 and Windows 7.  To release and renew IPv6 addresses in Windows 7, use the commands ipconfig /release6 and ipconfig /renew6.  To use IPv6 eui-64 addressing with stateless auto-configuration in Windows 7, enter the command netsh interface ipv6 set global randomizeidentifiers=disabled, otherwise Windows will create a random string of hex characters for the host portion of the IPv6 address, instead of using a modified version of the MAC address per the eui-64 standard.

With Dual-Stack enabled, the RV042 can provide IPv6 addresses to devices on its LAN via DHCP or stateless auto-configuration.  My test RV042 had a LAN IPv6 address of fc00::1.  The RV042's IPv6 DHCP default configuration dished out IPv6 addresses in the fc00::100-17f range.  My PC was issued fc00::13c and I could successfully ping the RV042's fc00::1 address.

Enabling stateless auto-configuration for IPv6 addressing tells the RV042 to advertise its IPv6 subnet in response to an IPv6 router solicitation multicast message.  This method of IPv6 addressing can be more efficient than DHCP, as the router doesn't need to maintain a list of IPv6 leases. 

If using stateless auto-configuration, the RV042 will advertise the fc00::/64 prefix, enabling clients to construct an IPv6 address based on this prefix and their MAC address.  With stateless auto-configuration enabled on the RV042, my PC gave itself an address of fc00::f2dd:f1ff:fe2b:5953, which is correct per the eui-64 standard and my MAC address of f0:dd:f1:2b:59:53.

The WAN interfaces on the RV042 support IPv6 addressing via static or DHCP.  As a simple test, I used the Cisco RV220W, which also supports IPv6, to supply an IPv6 address via DHCP to the RV042.  As you can see in Figure 5, the WAN 2 interface on the RV042 has an IPv6 address of fec0::100/64, which is from the range of addresses I configured on the RV220W.

WAN status showing IPv6

Figure 5: WAN status showing IPv6

An additional IPv6 function on the RV042 is 6to4 tunneling, which facilitates IPv6 connectivity through an IPv4 network.  Enabling 6to4 tunneling on the RV042 tells the router to advertise a 2002::/ subnet to LAN clients capable of 6to4 tunneling. 

A 6to4 enable router has to add its own IPv4 address in the 2002 address it advertises.  The WAN IP address on my RV042 was = a652:bdc1 in hex, and the RV042 correctly advertised the 2002:a652:bdc1::/64 prefix.  (Isn't IPv6 fun!?)

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