DHCP Server Port-Based Address Allocation

[ljohnsson]

Hi
I'm trying to use the feature in a Cisco Switch that should be able to allocate an IP-address to a client based on what port it connects to (reason is is we have to replace a HW on a specific port the new HW SHALL automatically use the same IP as the old HW)
I have used information in this link that talks about this feature
IP Addressing: DHCP Configuration Guide, Cisco IOS Release 12.2SX - DHCP Server Port-Based Address Allocation [Cisco IOS Software Releases 12.2 SX] - Cisco

So when I configure this like this (snippet from config) the DHCP server in the switch gives out the same IP to clients connecting to the ports, because it uses Vl1 as client-id instead of the actual interface id (like Gi0/1).  See the debug provided below where all DHCP request from ports is sending 0056.6c31  as client id (this is Vl1 translated from using ascii-table)

Any ideas if this is a bug or I have done something wrong configuring my switch ?

-----Snippet from config------

ip dhcp use subscriber-id client-id
ip dhcp subscriber-id interface-name
!
ip dhcp pool TEST
network 10.10.10.0 255.255.255.0
default-router 10.10.10.1
dns-server 8.8.8.8
option 150 ip 10.10.10.5
lease 0 0 3
address 10.10.10.10 client-id "Gi0/0" ascii
address 10.10.10.11 client-id "Gi0/1" ascii
address 10.10.10.12 client-id "Gi0/2" ascii
address 10.10.10.13 client-id "Gi0/3" ascii
address 10.10.10.20 client-id "Vl1" ascii

!
interface GigabitEthernet0/1
switchport mode access
ip dhcp relay information option server-id-override
ip dhcp server use subscriber-id client-id

------ DEBUG part ------

*Nov 7 09:26:20.312: DHCPD: Reload workspace interface Vlan1 tableid 0.
*Nov 7 09:26:20.312: DHCPD: tableid for 10.10.10.1 on Vlan1 is 0
*Nov 7 09:26:20.312: DHCPD: client's VPN is .
*Nov 7 09:26:20.313: DHCPD: using subscriber-id as client-id
*Nov 7 09:26:20.313: DHCPD: using received relay info.
*Nov 7 09:26:20.314: DHCPD: DHCPDISCOVER received from client 0056.6c31 on interface Vlan1.
*Nov 7 09:26:20.314: DHCPD: using received relay info.
*Nov 7 09:26:20.314: DHCPD: Sending DHCPOFFER to client 0056.6c31 (10.10.10.20).
*Nov 7 09:26:20.315: DHCPD: no option 125
*Nov 7 09:26:20.316: DHCPD: creating ARP entry (10.10.10.20, 5254.0019.6cf0).
*Nov 7 09:26:20.317: DHCPD: unicasting BOOTREPLY to client 5254.0019.6cf0 (10.10.10.20).
*Nov 7 09:26:20.319: DHCPD: Reload workspace interface Vlan1 tableid 0.
*Nov 7 09:26:20.319: DHCPD: tableid for 10.10.10.1 on Vlan1 is 0
*Nov 7 09:26:20.319: DHCPD: client's VPN is .
*Nov 7 09:26:20.319: DHCPD: using subscriber-id as client-id
*Nov 7 09:26:20.319: DHCPD: DHCPREQUEST received from client 0056.6c31.
*Nov 7 09:26:20.319: DHCPD: Sending DHCPACK to client 0056.6c31 (10.10.10.20).
*Nov 7 09:26:20.319: DHCPD: no option 125
*Nov 7 09:26:20.319: DHCPD: creating ARP entry (10.10.10.20, 5254.0019.6cf0).
*Nov 7 09:26:20.319: DHCPD: unicasting BOOTREPLY to client 5254.0019.6cf0 (10.10.10.20).
*Nov 7 09:26:26.307: DHCPD: Reload workspace interface Vlan1 tableid 0.
*Nov 7 09:26:26.307: DHCPD: tableid for 10.10.10.1 on Vlan1 is 0
*Nov 7 09:26:26.307: DHCPD: client's VPN is .
*Nov 7 09:26:26.308: DHCPD: using subscriber-id as client-id
*Nov 7 09:26:26.309: DHCPD: using received relay info.
*Nov 7 09:26:26.309: DHCPD: DHCPDISCOVER received from client 0056.6c31 on interface Vlan1.
*Nov 7 09:26:26.309: DHCPD: using received relay info.
*Nov 7 09:26:26.310: DHCPD: Sending DHCPOFFER to client 0056.6c31 (10.10.10.20).
*Nov 7 09:26:26.311: DHCPD: no option 125
*Nov 7 09:26:26.311: DHCPD: creating ARP entry (10.10.10.20, 5254.000e.80fe).
*Nov 7 09:26:26.312: DHCPD: unicasting BOOTREPLY to client 5254.000e.80fe (10.10.10.20).
*Nov 7 09:26:26.323: DHCPD: Reload workspace interface Vlan1 tableid 0.
*Nov 7 09:26:26.323: DHCPD: tableid for 10.10.10.1 on Vlan1 is 0
*Nov 7 09:26:26.324: DHCPD: client's VPN is .
*Nov 7 09:26:26.324: DHCPD: using subscriber-id as client-id
*Nov 7 09:26:26.324: DHCPD: DHCPREQUEST received from client 0056.6c31.
*Nov 7 09:26:26.325: DHCPD: Sending DHCPACK to client 0056.6c31 (10.10.10.20).
*Nov 7 09:26:26.325: DHCPD: no option 125
*Nov 7 09:26:26.326: DHCPD: creating ARP entry (10.10.10.20, 5254.000e.80fe).
*Nov 7 09:26:26.326: DHCPD: unicasting BOOTREPLY to client 5254.000e.80fe (10.10.10.20).
*Nov 7 09:26:31.316: DHCPD: Reload workspace interface Vlan1 tableid 0.
*Nov 7 09:26:31.317: DHCPD: tableid for 10.10.10.1 on Vlan1 is 0
*Nov 7 09:26:31.317: DHCPD: client's VPN is .
*Nov 7 09:26:31.317: DHCPD: using subscriber-id as client-id
*Nov 7 09:26:31.318: DHCPD: using received relay info.
*Nov 7 09:26:31.318: DHCPD: DHCPDISCOVER received from client 0056.6c31 on interface Vlan1.
*Nov 7 09:26:31.319: DHCPD: using received relay info.
*Nov 7 09:26:31.319: DHCPD: Sending DHCPOFFER to client 0056.6c31 (10.10.10.20).
*Nov 7 09:26:31.320: DHCPD: no option 125
*Nov 7 09:26:31.320: DHCPD: creating ARP entry (10.10.10.20, 5254.0002.4dec).
*Nov 7 09:26:31.321: DHCPD: unicasting BOOTREPLY to client 5254.0002.4dec (10.10.10.20).
*Nov 7 09:26:31.330: DHCPD: Reload workspace interface Vlan1 tableid 0.
*Nov 7 09:26:31.331: DHCPD: tableid for 10.10.10.1 on Vlan1 is 0
*Nov 7 09:26:31.331: DHCPD: client's VPN is .
*Nov 7 09:26:31.332: DHCPD: using subscriber-id as client-id
*Nov 7 09:26:31.332: DHCPD: DHCPREQUEST received from client 0056.6c31.
*Nov 7 09:26:31.332: DHCPD: Sending DHCPACK to client 0056.6c31 (10.10.10.20).
*Nov 7 09:26:31.333: DHCPD: no option 125
*Nov 7 09:26:31.333: DHCPD: creating ARP entry (10.10.10.20, 5254.0002.4dec).
*Nov 7 09:26:31.334: DHCPD: unicasting BOOTREPLY to client 5254.0002.4dec (10.10.10.20).

[balaji.bandi]

what is the switch model, what IOS Code running.

what is the outcome if you remove this  line from dhcp pool config : address 10.10.10.20 client-id "Vl1" ascii

what is the config applied in vlan1 : show run interface vlan 1 ?

like to know what is device MAC Address - 0056.6c31. (switch mac address, what mac address of device ? you trying to connect 5254.0002.4dec ?)

[ljohnsson]

The switch is in CML running version 15.2 (just to be able to test the functionality easily)
Cisco IOS Software, vios_l2 Software (vios_l2-ADVENTERPRISEK9-M), Experimental Version 15.2(20200924:215240) [sweickge-sep24-2020-l2iol-release 135]

If I remove that address command the clients get allocated an IP-address from the pool, but still all gets the same IP, as they report the same client-id

On vlan1 there is only an IP-address configured, without this the internal DHCP server vill not provide any IP-address to the clients
interface Vlan1
ip address 10.10.10.1 255.255.255.0
end

[balaji.bandi]

You may not get all features you looking to test over Virtual or CML,

I will turn off all port and clear MAC table and test it (if not working there may be Limitation of virtual)

i will test on my CML later when i get chance.

[MHM Cisco World]

one by one with me 
you have one router which is relay and DHCP local server in same times??

[ljohnsson]

The goal is to have the switch assigning IP-addresses to hosts connection to different ports in the switch, and always assigning the same IP-address to whatever connects to a port based on what port it connects to, so if something connects to port gi 0/0 it shall gets IP-address 10.10.10.10, something connection to port gi 0/1 shall get address 10.10.10.11 and so on
I have to configure interface VLAN1 (or whatever VLAN those ports will be assigned to) to have the switch handling out IP-addresses. If I only configure the ip dhcp pool and its related commands no IP's was assigned to the hosts. 
The switch is not acting as an router, just handling out IP-addresses to the clients that connects to it

[MHM Cisco World]

OK, 
but still 
Client-SW-R(relay)-R(local DHCP server)
this is flow of DHCP 
Client connect to SW in Port X, 
SW can run DHCP snooping, which make SW add Op82 include VLAN-ID + Port
R(relay) can forward it add more to Op82 or keep it 
R(local DHCP server) config DHCP with Class each class config Op82 and IP assign to it.

[ljohnsson]

So what do you suggest I change to get it working ?

[ljohnsson · Accepted solution]

OK, I digged out an old Catalyst 2960 and did the same test there. Worked perfect, so CML and the IOS version there on the switch is really having trouble.   Problem solved