The opening view into the NetVanta 3120 is a useful live display of key details which automatically refreshes every 5 seconds. Details including uptime, memory, CPU utilization, storage space, and status of all physical interfaces are presented, as shown in Figure 6. Interestingly, the System Information screenworked with IE6.0 and Safari, but not Firefox 3.0.
Figure 6: System Information screen
The System menu also has a Getting Started menu option, which will walk you through configuring the WAN interface, adding VLANs, setting up routing protocols (RIP and OSPF) and prompting you to save your selections. But I took the manual route and configured things individually.
The WAN interface, listed as the "Public" interface, supports Ethernet connections common to cable ISPs, or PPPoE connections common to DSL. I had no problem connecting the 3120 to Time Warner Cable and getting on line. The 3120 also includes a client for DynDNS.org, to keep your dynamic public IP address pointed to a domain name.
The Private Interface submenu is the VLAN menu, as shown in Figure 7. VLANs can be added in this section along with the IP address for each VLAN interface on the router. By default, the Private interface is VLAN1.
Figure 7: VLAN Configuration
The 3120 can function as a DHCP server for multiple different subnets/VLANs. I added a second DHCP pool for the Wireless LAN's subnet (10.10.12.0/24), shown in Figure 8, so wireless devices could be differentiated from other devices on the network based on IP addresses.
Figure 8: DHCP Pools
Additional options in the System menu include support for SNMP (v1, v2c, v3), with email notification capability and Link Layer Discovery Protocol (LLDP). LLDP is a vendor-neutral Layer 2 protocol allowing devices to communicate capabilities, device type, and VLAN information.
Switching and Routing Options
For a router with only 4 switch ports, the 3120 has significant Layer 2 switching features, including support for VLANs, 802.1q trunking, link aggregation, spanning tree protocol (802.1d and 802.1w), and port based security. In addition, QoS parameters can be applied based on CoS and DSCP markings and traffic can be managed using Weighted Round Robin and Priority Queuing. I tested VLAN functionality in conjunction with the Access Point which I'll cover in the Wireless section.
Even with a dumb switch connected to one or more of its ports, the 3120's VLAN features allow for separating various devices into different networks and applying different controls such as prioritization or firewall restrictions based on subnet or VLAN.
A simple strategy with the 3120 would be to define a separate VLAN for each switch interface, and connect unmanaged switches to each of the 3120's LAN ports. This would be a cost effective way to run up to 4 separate VLANs, while using inexpensive Layer 2 switches. On a more advanced scale, a 3120 connected to one or more managed switches that support VLANs and 802.1q trunking can be the hub of an even more sophisticated small network.
The 3120's routing features are impressive. Static and dynamic RIP routing is supported by most small network routers today, yet the 3120 also supports Open Shortest Path First (OSPF) and BGP (Border Gateway Protocol). OSPF and BGP are non-proprietary and powerful routing protocols, with OSPF useful for passing route updates between routers within an organization, and BGP for passing route updates between routers of different organizations.
Figure 9 is a screen shot of the 3120's route table showing eight routes of types Other, Connected, and Static. Routes learned through a dynamic routing protocol such as RIP, OSPF, or BGP would be listed with that protocol as its type.
Figure 9: Routing screen
The top "Other" route is the default route for general Internet traffic, while the first three "Connected" routes are internal routes for VLAN1 and 2, as well as a “loopback” interface I created. The fourth Connected route is for the WAN interface, the two Other routes are the VPN tunnels, and last is a Static route I entered to route traffic through another router on my LAN.
“Loopback” interfaces are virtual interfaces that are useful in routing protocols and network testing since they can be pinged but are not susceptible to circuit or network failure.