[j-nsp] JUNOS 8.5 dhcp server confusion

Joe Abley jabley at ca.afilias.info
Tue May 13 09:55:44 EDT 2008

Hi all,

I came across an oddity the other day that might ring bells for  
someone here. I'm having trouble with the dhcp server, and in  
particular getting static bindings (fixed assignment of IP addresses  
for particular client MACs) to work. This is not an Afilias exercise,  
so don't read too much into the from address I'm using.

Router is a J2320 running 8.5R3.4. Config looks like the snippet below.

What happens when the client with MAC 00:50:56:01:01:64 requests a  
lease is that a dynamic binding from the dynamic pool is formed, and  
the client is not given the A.B.C.164 address. I've tried the config  
below with and without the address-range phrase in the pool stanza,  
and the result is the same.

When I was testing last night, I saw the following kind of output  
recorded on the router (not pasted; this is constructed from memory):

jabley at router> show system services dhcp binding
IP address       Hardware address   Type     Lease expires at
A.B.C.164        00:50:56:01:01:64  static   never
A.B.C.166        00:50:56:01:01:64  dynamic  <timestamp>
jabley at router>

which seemed very odd. What use is a static binding if the server will  
happily make up a dynamic binding for the same MAC?

I find the documentation for the JUNOS DHCP server to be quite vague.  
Does anybody else have a working DHCP config, ideally on 8.5, that  
includes static bindings and works?


system {
         dhcp {
             maximum-lease-time 7200;
             default-lease-time 3600;
             name-server {
             traceoptions {
                 file jdhcpd.log size 10m files 10;
             pool A.B.C.160/29 {
                 address-range low A.B.C.164 high A.B.C.166;
                 router {
             static-binding 00:50:56:01:01:64 {
                 fixed-address {

interfaces {
     ge-0/0/3 {
         unit 100 {
             vlan-id 100;
             family inet {
                 address A.B.C.162/29 {
                     vrrp-group 100 {
                         virtual-address A.B.C.161;

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