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uc560 dhcp

markbretel1
Beginner
Beginner

UC560, how do i disable dhcp on vlan1 ? Due to joining customers subnet?

12 Replies 12

Darren DeCroock
Enthusiast
Enthusiast

Mark,

Currently, there is not a way to disable DHCP in CCA...   (I believe this option will be added to the next version of CCA.)

*** Warning: If you are using CCA only, or are not a "UC Specialized" partner, modifications though CLI can void support for CCA when calling into support in the future.  If you have questions about this, or need asistance please call into support. ***

To disable DHCP, just telnet into the UC560:

Config T

no ip dhcp pool data

exit

write mem

Thank you,

Darren

Hi Darren,

*** Warning: If you are using 
CCA only, or are not a "UC Specialized" partner, modifications though 
CLI can void support for CCA when calling into support in the future.  
If you have questions about this, or need asistance please call into 
support. ***

I would suggest you check this out and make sure this is the case, potentially you are alienating a partner from being able to successfully integrate a UC into a greyfield site, and since CCA does not currently support the removal of it acting as a DHCP server, the engineer must have recourse.

I for one will fight tooth and nail about voiding my support contract if I was to be pulled up on this (And 90% of the deployments at the moment this needs to be done), actually I know here in Australia you would hold no legal grounds to void that support contract at all, this in effect would be imposing a restriction without alternative, and saying that UC specialization is a requirement or alternative would not hold water either as this then defeats the purpose of becoming Select Certified partner and having engineers obtain the SMB 650-195 certification.

Put it in CCA and then impose the explicit rule, that makes sense to me

I am pointing this out just so you are aware of it, as this has been raised many times when sitting around with other Cisco partners and chatting over drinks, it is clear that there is a high level of frustration out there and certain things need to be carefully managed by Cisco.

And also you are right, you cannot exclude the whole subnet as it still broadcasts and a tussle will occur with the existing DHCP server, tried this now twice and both times have failed, so back to CLI and just remove it and things go back to their merry way...

(PS) Not having a go at you please do not see it that way, just pointing out the obvious

Cheers,

David.

Cheers, David Trad. **When you rate a persons post, you are indicating a thank you or that it helped, but at the same time you are also helping to maintain the community spirit - You don't have to rate posts and you wont be looked down upon :) *

I agree with David, though every Cisco rep needs to cover their "backs" when supporting CLI customizations.  Obviously Cisco is trying to keep their techs from spending too much time on the phone with customers trying to figure out their custom configurations.  Even with this new "rule", I found techs to be extremely helpful. 

David,

I understand the need to make a modification like this, and my "Warning" was more of a standard message when posting any CLI modifications for a UC540 or UC560.  For this particular case there is no other way to disable the DHCP server, other than to remove the pool.  (Which should be added to a future version of CCA.)  I just want to make sure that those partners using CCA only, or are not supported though CLI, understand the making CLI changes can be an issue with CCA fuctionality, and technical support.  Yes, this is a minor adjustment, but where do we draw the line..  There are just too many possibilities and options through CLI to say what is and is not OK.

For those CCA only partners, I would recomend that they call into support so that if a CLI change is required, it can be documented, and since there are many different ways to do things in CLI, the approved CLI modification is used.  So that future versions of CCA will recognize the changes and not cause any issues.

Thank you,

Darren

Hi Darren,

Yes, this is a minor adjustment, but where do we draw the line..  There are just too many possibilities and options through CLI to say what is and is not OK.

Agreed whole heartedly

For those CCA only partners, I would recomend that they call into support so that if a CLI change is required, it can be documented, and since there are many different ways to do things in CLI, the approved CLI modification is used. 

I understand and appreciate this, just keep in the back of your mind though that this is a long process and is ok if you come across the problem in the staging process, but once out onsite many of the decisions you have to make is on an instant basis, waiting to get through to support can at times be a challenge, so if the CLI modifications is within approved methods or guides, then it would be good to just be able to e-mail to support the changes made (Maybe the configuration file) so that way it is registered on their system that way and a confirmation e-mail be sent back to the engineer

Just a thought

I understand the need to make a modification like this, and my "Warning"
 was more of a standard message when posting any CLI modifications for a
 UC540 or UC560. 

I agree that this needs to be done, just be careful though how you put it forward it is quit scary reading some of the messages at times because they come across as being explicit and non-wavering.

Thank you for clearing some things up though

Cheers,

David.

Cheers, David Trad. **When you rate a persons post, you are indicating a thank you or that it helped, but at the same time you are also helping to maintain the community spirit - You don't have to rate posts and you wont be looked down upon :) *

renato.guimaraes
Beginner
Beginner

If you prefer not to mess with CLI, you can add exclusions to the DHCP pool. Just exclude the entire pool from 192.168.10.1 to 192.168.10.254 (for example).

Even excluding the entire range of the DHCP pool can still cause issues, as it does not disable the DHCP pool, and it will still respond to DHCP requests, just will not have any available addresses to give out.

Thank you,

Darren

It would be amazing if there was a published list of approved CLI-based changes.  Removing a DHCP pool, for example is pretty simple.  Creating custom dial plans and customer-specific call flows is not...

Philip Denton
Beginner
Beginner

I wonder if we could just create ACLs on that VLAN Interface that prevent DHCP requests/replies?

This is a really old thread.

Turning off DHCP per-vlan is supported in the current version of CCA.

Hello Phil,

First off, you are posting on a thread that is almost 2 years old.

In the newest version of CCA, the data DHCP pool can be removed.

As far as an approved list of CLI-based changes.  This would be a huge undertaking, as there are so many options that can be entered in CLI (millions).  CCA is a program that reads the current configuration, and then displays this information in a graphical interface.  The issue is that there are so many variations, CCA would have to be programed for everything.  Currently even with some minor changes, CCA will ignore those changes and display the information, but then when you make a change to that section, it also is likely to overwrite your CLI changes.

This is why support has a policy that the unit will be supported by CCA only, or CLI only (with a contact and CLI certification).  Hybrids(using both) of CCA and CLI are not supported.  Trying to figure out what has been changed, and if those changes are effecting CCA, or if CCA overwrote some of your CLI modifications would consume a tremendous amout of time for the support engineers, as every configuration is different.

Thank you,

Darren

Daniel, that's true but I still can't find a way in CCA 3.2.2 to competely disable/remove the Voice VLAN, which my client is serving off their core switch.  I guess I should look at removing the scope from the switch rather than the UC560?

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