DHCP not issuing in order

[jeevan.koganti]

Hi,

I have DHCP on my cisco WAN 881 router, but everytime router does not issue DHCP in order.

so either i have restart the router every day or i have to clear clear arp & Clear ip dhcp binding.

Can any one help me on this??

Thanks in advance.

Regards,             

[paul driver]

Hello

can you elaborate on what you mean by alocating addresses in order?

what is your requirement for this?

res
Paul


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[jeevan.koganti]

Hi,

I have configured DHCP range from 192.168.0.10 192.168.0.100

In this range cisco router always skips few IP's eventhough they are not allocated to user.

Evertime DHCP range gets full and needs restart or clearing DHCP range manually.

Hope you understood my problem.

Regards,

[Jan Hrnko]

Hi Jeevan,

I have configured DHCP range from 192.168.0.10 192.168.0.100
In this range cisco router always skips few IP's eventhough they are not allocated to user.

can you please paste the configuration of DHCP on your rotuer? You have mentioned that some of the IPs are not even allocated, maybe there is a misconfiguration problem.

Evertime DHCP range gets full and needs restart or clearing DHCP range manually.

If you want to reduce the lease time, use this command:

Router(dhcp-config)# lease {days[hours][minutes] | infinite}

Best regards,

Jan

[jeevan.koganti]

Hi,

Below is the config..

ip dhcp excluded-address 192.168.0.1 192.168.0.9
ip dhcp excluded-address 192.168.0.16
ip dhcp excluded-address 192.168.0.20
ip dhcp excluded-address 192.168.0.26
ip dhcp excluded-address 192.168.0.31 192.168.0.34
ip dhcp excluded-address 192.168.0.38
ip dhcp excluded-address 192.168.0.50
ip dhcp excluded-address 192.168.0.100 192.168.0.254

ip dhcp pool Cisco
network 192.168.0.0 255.255.255.0
default-router 192.168.0.100
dns-server 192.168.0.100 192.168.0.16
lease infinite
update arp

Router sikps many IP's in the range.

Regards,

[Jan Hrnko]

Hi Jeevan,

well, you do have a lot of IP addresses excluded from the usable range, to be honest. If my calculations are correct, precisely 82 addresses can be used for hosts.

The next major problem is the lease time of infinite. That way, the bindings will never be flushed (if not done manually through the clear command or by restarting the router). What about trying the command I have provided in the previous post? For instance:

Router(dhcp-config)# lease 0 0 30

That way, the lease time will be set to 30 minutes. After that, it will age out dynamically.

How many hosts do you have on your network and why do you exclude so many addresses?

The router should go in the order, I believe, which addresses are skipped for example? Can you verify this by using show ip dhcp binding?

Best regards,

Jan

[paul driver]

hello

if.your dhcp scope.is being exhausted either drop the lease time to a short interval or extend the private scope to a possible 23 bit mask which will give you another 254 hosts.

you will also need to change the svi ip mask ro accomodate this new value

res
paul

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