Cisco Registrar don´t mark leased ip-addresses correct

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Jul 22nd, 2003
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Hi,


we have the following problem. Sometimes (most with WLAN-Clients) if a client request an ip-address from our Registrar DHCP-Server, the server sends the correct information (ip, mask, dns etc.) but don´t mark the assigned ip-address as leased in his database. So in the next time if an other client from the same ip-subnet request an ip-address the server will assign the same ip-address as befor. Because this ip-address is also available (per ping) the server mark this ip-address as unavailable and assign the second client the next free ip-address. In this scenario i have no trouble with the clients because the server send him the right ip-addresses, but if the problem occurs often there are no free ip-addresses in the subnet (because all of them are unavailable) and the clients can´t release ip-addresses.


Has anyone an idea ??



THX

Larry

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amritpatek Mon, 07/28/2003 - 06:57
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I guess this is an issue with ACU. Had a similar problem earlier. Upgrading it to ACU version 5.0 might fix the problem.

keyushah Mon, 07/28/2003 - 09:59
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This is a client issue. As per DHCP protocol, the server will wait for a ACK from the client before reserving the lease. Seems like the client is accepting the lease and not sendign the ACK, OR, the ACK is not reaching the CNR server. Either way, you will need to do a packet capture and find out what's going on on your network.

l.meyer Thu, 07/31/2003 - 05:52
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Thanks for your reply.


I have captured the conversation between the client <> HSRP Router(Relay Agent) <> DHCP Server. RFC2131 describe that the server sends the DHCPACK (not the client), so I think the conversation is OK. Do you have an other idea ?




Frame Status Source Address Dest. Address Size Rel. Time Delta Time Abs. Time Summary

1 M [192.168.181.68] [192.168.250.40] 342 0:00:00.000 0.000.000 18.03.2003 12:57:12 DHCP: Request, Message type: DHCP Release

2 [0.0.0.0] [255.255.255.255] 342 0:00:03.869 3.869.784 18.03.2003 12:57:16 DHCP: Request, Message type: DHCP Discover

3 [10.242.161.3] [10.242.161.124] 342 0:00:04.191 0.321.781 18.03.2003 12:57:16 DHCP: Reply, Message type: DHCP Offer

4 [0.0.0.0] [255.255.255.255] 373 0:00:04.192 0.000.451 18.03.2003 12:57:16 DHCP: Request, Message type: DHCP Request

5 [10.242.161.2] [10.242.161.124] 342 0:00:04.193 0.001.634 18.03.2003 12:57:16 DHCP: Reply, Message type: DHCP Offer

6 [10.242.161.3] [10.242.161.124] 342 0:00:04.247 0.053.419 18.03.2003 12:57:17 DHCP: Reply, Message type: DHCP Ack

7 [10.242.161.2] [10.242.161.124] 342 0:00:04.372 0.125.101 18.03.2003 12:57:17 DHCP: Reply, Message type: DHCP Ack

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