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General Router FAQ

Fixing a DHCP Assignment

How do I fix a DHCP allocation ?

The router's DHCP service function allocates an IP address to the client PCs on your network automatically; it also provides them with the gateway and DNS server addresses. If you are using the DHCP server facility on the router, you may need to fix an allocation so that the same client (PC) always gets the same IP address. This might be useful for a device such as an Ethernet webcam which you need to always know the IP address of.

The method for fixing a DHCP allocation may vary depedning on router model/firmware.

On Vigor2820 and Vigor2800 series routers (firmware 2.7 and later) you can fix allocations from the regular web interface. Select the 'Bind IP to Mac' option in the Firewall menu.

Vigor2800 Bind IP to MAC

In the above screenshot, you can see on the left a convenient list of current 'known' devices connected to the Vigor router. this information is taken from the ARP cache. You can select any of those and press Add to move it to the pre-set list on the right, or enter a MAC address and desired IP allocation manually in the box on the bottom left. Once you are happy with the setup, press the OK button at the bottom to save the settings.

On Vigor2600 series routers, access the Telnet interface with the following syntax :

srv dhcp fixip add <IP Address> <MAC Addr> <HostID>

The IP address is specified in dotted octets, e.g. and the MAC address in six hex octets, e.g. F0-DE-DB-10-12-71

You can delete assignments with the del command, for example :

srv dhcp fixip del

The 'clr' command will clear all set values.

How do I set the domain name and lease time issued by the DHCP server ?

If it's necessary for your DHCP clients to be allocated a specific domain name, on the Vigor2200 series you can use the following command from the telnet interface :

sys domainname [domain]

To set the lease time (i.e. time before the allocation expires), you can use :

srv dhcp leasetime [xxx]

How do I change the router's SNMP name ?

To set the router's name (as shown in SNMP and telnet) use :

sys name my.router

NOTICE : This document is © SEG Communications and may not be distributed without specific written consent. Information and products subject to change at any time without notice. Check each model for specific feature support.