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Accepted
Matthew Rankin
Asked: 2009-12-01 07:00:04 +0800 CST

What's the purpose of setting the static IP entries in a Linksys RV082 router?

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I'm wanting to configure our Linksys RV082 wired router as our primary DHCP server and then have our Linksys WRT54G wireless router as a secondary DHCP server. My plan is to have them serve different ranges of IPs as shown below (showing host portion only and using CIDR range of 10.10.100.0/24).

The RV082 has the ability via its web based configuration to enter the static IPs even when acting as the DHCP server, which is what I want since we have the routers, servers, and printers configured with static IPs and the local clients configured with dynamic IPs. In addition to setting the static IP, for each entry the RV082 requires you to include the MAC address, name, and whether it's enabled (checkbox). In contrast, the WRT54G does not appear to have the ability to enter information about the static IPs.

This leads me to my question: What's the purpose of setting the static IP entries in the RV082?

IP Configuration

  • 1-15 -- Static IPs for wired routers
  • 16-29 -- Static IPs for wireless access points
  • 30-99 -- Static IPs for servers
  • 100-126 -- Static IPs for printers
  • 127-185 -- Dynamic IPs for local clients served from primary DHCP server (RV082)
  • 186-244 -- Dynamic IPs for local clients server from secondary DHCP Server (WRT54G)
  • 245-254 -- Dynamic IPs for VPN clients server from VPN server (RV082)
cisco

2 Answers

  1. Best Answer

    The only thing needed for static IP assignment from DHCP is the MAC address. The other items must be there for administrative convenience. I have found it easier to use Excel or a wiki page, "hard code" the static devices, and take the static IP ranges out of the DHCP pool.

    Now, there is no convenient way to have a "primary" and "backup" DHCP servers, particularly with low end gear. I don't think it will work as you are expecting, and you will see random confusion in IP addresses.

    It also looks like you are over-thinking the IP protocol, pre-assigning too many statics and leaving the DHCP space too small. Are you really going to have 126 fixed IP devices? I would have 1-60 set as fixed, 61-254 on DHCP. Having a DHCP server with no free addresses is a tough problem to fix on the fly.

    My suggestion is to put the wireless devices on a separate subnet and have the WRT54G serve DHCP and do NAT. An alternative is to have the RV082 be the DHCP server and have the WRT54G proxy DHCP requests and not do it's own DHCP.

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  2. The RV082 allows you to assign a fixed IP address to clients using DHCP for network configuration. This allows you to just put all your machines on DHCP, and still benefit from fixed IP address assignments. You are then able to use IP based configuration (e.g. NAT port forwarding), while retaining all the conveniences of central DHCP management.

    The WRT54G (with the factory firmware) does not have this ability.

    I see no benefit in setting up the WRT54G as a secondary DHCP server, and would just disable this feature.

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