maximum number of IP dhcp servers

[lizardo]

Hello everyone, I have a Cisco C9200L-24T-4X switch, with firmware 17.6.4, I would like to know how many pools can be created and how many IPs in total at most it assigns to all networks.

Thank you.

[MHM Cisco World]

I search cisco IOS-XE not specify the limit of DHCP Pool and limit the DHCP IP, Can I know why you need to know the limit ?

[lizardo]

Hi, sure, I work in a large institution and use the C9200 as a DHCP server, checking the switch, which has delivered approx 4550 ip via dhcp and in some places when trying to connect to the network does not give IP to the client.

That's why the query, I want to rule out that it is the maximum amount of IPs delivered by the switch.

It does not seem to be a problem of the wireless equipment since the first ones that connect to the equipment if it gives them network, it seems to be an exhaustion of IP addresses.

[MHM Cisco World]

show ip dhcp server statistics <<- share this

[lizardo]

Hello, this is the capture of this instant.

SWITCH#show ip dhcp server statistics
Memory usage 1016761
Address pools 83
Database agents 0
Automatic bindings 2424
Manual bindings 0
Expired bindings 91535
Malformed messages 48
Secure arp entries 0
Renew messages 294841
Workspace timeouts 0
Static routes 0
Relay bindings 0
Relay bindings active 0
Relay bindings terminated 0
Relay bindings selecting 0

Message Received
BOOTREQUEST 281
DHCPDISCOVER 1772654
DHCPREQUEST 1127691
DHCPDECLINE 285
DHCPRELEASE 20227
DHCPINFORM 45297
DHCPVENDOR 0
BOOTREPLY 0
DHCPOFFER 7
DHCPACK 0
DHCPNAK 0

Message Sent
BOOTREPLY 121
DHCPOFFER 673326
DHCPACK 976741
DHCPNAK 83785

Message Forwarded
BOOTREQUEST 0
DHCPDISCOVER 0
DHCPREQUEST 0
DHCPDECLINE 0
DHCPRELEASE 0
DHCPINFORM 0
DHCPVENDOR 0
BOOTREPLY 0
DHCPOFFER 0
DHCPACK 0
DHCPNAK 0

DHCP Relay ACK drop 1054652040
DHCP-DPM Statistics
Offer notifications sent 0
Offer callbacks received 0
Classname requests sent 0
Classname callbacks received 0

Port Based Allocation Statistics
Discover MAC change 3638277768
Request MAC change 4208703112
Invalid binding in fwd req 484226696

[Flavio Miranda]

Hi

 I believe theres no limit and you can check that

IP dhcp pool test-pool

 network 1.0.0.0 255.0.0.0

If the switch accept this pool, there will be no limit

 Now, this is a switch not a dhcp server. I wouldnt trust a switch a dhcp pool bigger then  100 IP

[lizardo]

Hi, that is relative, I have a switch of another brand, it only supports 16 pools, let's assume that I only enable 200 ips per pool, that would give me 3200 ips, but the equipment only delivers at most 1024 ips in total per dhcp.

[Leo Laohoo]

I would not recommend using a switch, particularly one that runs on IOS-XE, to be the DHCP server or a large pool like that. 

When that switch crashes, invariably it will, there will be a lot of angry people.

[lizardo]

Hi, thanks for the advice, it started as a temporary thing and now it is permanent. I will check dhcp server options.

[Richard Burts]

It is interesting that you do have a switch from a different vendor that does place a limit on DHCP implementation. I believe that Cisco does not implement such a restriction. It is certainly possible that a particular pool may not have sufficient addresses in it, the pool gets exhausted and some devices do not receive IP addresses.

I agree that while a switch might be an appropriate choice to act as DHCP server in smaller environments, but at the scale that you describe that using a switch is not an optimum choice. You would do well to use a dedicated device to provide DHCP assignments.

[lizardo]

Hi, I checked that pool and only about 80% of available ips were in use.

I am looking at dhcp server options to leave the switch as dhcp server.

thank you all for your advice.