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On a multiple Vlan network I have two Vlans that are in my domain group. One is funcitoning fine while the other is not. If I place any client in the group that is not to accept BOOTP lease it works fine it is something to do with the request and reply for the WINS or NetBIOS type81 request on devices that reside on my secondary network or VLAN. One note the WINS and DNS servers that are given as reply to the clients are on the primary vlan and not on this non working secondary.

For a client that worked the packet sequence seen on its switch port was:

Client -> Broadcast DHCP Discover (I want 141.211.###.###) 12.92 -> 141.211.###.### DHCP Offer (You can have 141.211.###.###) Client -> Broadcast DHCP Request (I accept 12.92's offer) 14.27 -> 141.211.###.### DHCP Offer (You can have 141.211.###.###) 12.92 -> 141.211.###.### DHCP ACK (You've got 141.211.###.###)

Note that the client sent its Request before the second offer from 14.27 arrives.

For a client that didn't work:

Client -> Broadcast DHCP Discover (I'll take anything) 12.92 -> 141.213.###.### DHCP Offer (You can have 141.213.###.###) 14.27 -> 141.213.###.### DHCP Offer (You can have 141.213.###.###) Client -> Broadcast DHCP Request (I accept 12.92's offer) Client -> Broadcast DHCP Request (I accept 12.92's offer) Client -> Broadcast DHCP Request (I accept 12.92's offer) Client -> Broadcast DHCP Request (I accept 12.92's offer)

But it never gets an ACK from 12.92.

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  • Do you have routes from the DNS and WINS servers to the non-working VLAN (VLAN2)?
  • Do you have your DNS server listed as authoritative for VLAN2 IP network? I.e. is the IP range for VLAN2 listed in your Reverse Lookup Zones?
  • What are you using to pass the DHCP broadcasts from VLAN to the other? Do you have a router between networks that could be interfering?
  • What do the logs on your client say?
  • What do the logs on the DHCP server say?

These are all questions that come to mind. One should show you the answer...

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  • Yes, routing using an external vlan with internal trunk ports on a e6509 10g interface to combine the five internal vlans to that external vlan. Yes, and Yes Cisco ASA5580-40 doing DHSCP relay. I think this problem may be caused by the DHCP relay on this box so I am now trying a DHCP relay server inside the network so it functions inside the interfaces ranther than outside. Sends request gets IP then reply is lost in translation it seems the second reply to WINS drops because it is not broadcast but UDP to the IP. DHCP server sees the ip address hand of then no reply to the WINs request.
    – Dr. Molden
    Oct 16, 2009 at 12:39

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