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Need help with client identifier & DHCP

Unanswered Question
Mar 10th, 2014
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I have created static hosts for all of my clients (interim measure until I get DNS servers built and running) on an SG300-20. I defined all of these allocations using MAC addresses.

However, several of my clients (1 Windows 7 workstation, 2 FreeNAS / FreeBSD storage servers and 1 HP color Laserjet printer) are still being dynamically assigned other addresses based on client identifier.

In all four cases, the client identifier being used by the switch is the MAC address with a leading "01" octet attached.

For example, my workstation has a MAC address of 00:10:18:E3:64:2F, which is defined as a static host based on that MAC address. The switch is using a client identifier of 01:00:10:18:E3:64:2F.

I am sure that I need to be entering a client identifier in the static host instead of the MAC address. From the discussions that I have read on here, that should look something like 0100.1018.e364.2f, but the static hosts GUI will not accept that. It won't allow me to type periods at all, and it won't accept 0100:1018:e364:2f, so I am clearly not entering this correctly.

 

Any help on how to resolve this / how the GUI is expecting the client identifier to be formatted?

 

Thanks!

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viningele Mon, 03/10/2014 - 20:34
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There's recent posts recently about this but IMHO it wasn't suffiently answered. Something if you create an entry and assume you should use a client ID it doesn't work either unless enter the MAC. I don't think we should to see what comes up as before we make a static entry. If we enter a MAC it should always work. The switch should also be smart enough if a MAC is enter and a client ID is obtained. How hard is it to do a compare string less the client ID prefix? The client ID is just the digits of the MAC, no .,: etc prefaced by 01 usuallu but not necassarily always. Also don't fill in the client name on the entry page or it won't work.
NafTan1970 Tue, 03/11/2014 - 07:20
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Hi,

 

  1. To enter client Identifier in the client identifier field - you can use one of the following formats:
    1. ​Enter the required value as a string with no delimiters (example 010022334455)
    2. Enter the required value as a string using pairs of chars separated with a colon (:) as a delimiter (for example 01:00:22:33:44:55)
  2. ​Regarding the first part of your post - when configuring a static host entry - the MAC address will be used as a parameter only if the DHCP discover packet did not include the client ID option (option 61). If the DHCP client does send frames with client ID field - the DHCP server on device will not look at the MAC address at all (even if it is entered as a static entry). That is why those host you mentioned got a dynamic and not static DHCP allocation.

Please rate my answer if they are helpful.

 

viningele Tue, 03/11/2014 - 10:38
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To me that's a bug. You can't know how to enter a host into the static bind table until you know whether it wil provide a client id. Like you said if you enter a MAC and comes up with a client id it doesn't recieve the assigned ip, if you assume the client id based on 01+MAC and it doesn't end up presenting a client id again the host doesn't get the assigned ip. For years with dumber switches I could take a list of MACs and enter them on my switches so that when a device came online if their default was dhcp it would obtain the address I wanted and I'd know where to find it. Now with these "smarter" switches I have to work harder so in some regards these switches are dumber than an Best Buy off the shelf switch. You should be able to fill in the MAC value and the switch should auto-complete the client id assuming a 01 prefix that cna be changed. Both values should be editable and maintained in their own tables for each host entry.

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