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From Saksham Srivastava <>
Subject RE: [DISCUSS] IP Address Reservation within a network
Date Tue, 22 Jan 2013 06:50:12 GMT
My comments inline. I will update the FS with the feedback.


From: Chiradeep Vittal []
Sent: Saturday, January 19, 2013 5:09 AM
To: CloudStack DeveloperList
Subject: Re: [DISCUSS] IP Address Reservation within a network

The current way of inferring a cidr from gateway and netmask is odd. I
support the addition of a 'cidr' parameter to the createNetwork API. If it
is supplied then that should be the basis of specifying the cidr rather
than the gateway/netmask combo.

[Saksham]: Thanks Chiradeep for your insight. I agree addition of new optional parameter "cidr"
but to maintain backward compatibility of the api, any one from Gateway/Netmask combo or cidr
could be used.

On 1/17/13 8:07 AM, "Sowmya Krishnan" <> wrote:

>Hi Saksham,
>To comment on your question:
>>>     Should shared guest networks also allow for IP reservation considering
>>>the current scenario where Start IP and End IP are mandatory during
>>>shared guest network creation.
>Isn't this functionality already implicitly present for shared networks
>since we specify network and start, end IPs during creation?
[Saksham] Yes, the functionality is already there but implicit.
We need to document the case of shared network in this context.
>Few comments on the FS:
>1. What is the reason for using Start IP and End IP in place of CIDR? Is
>it to make it consistent with shared Network? Considering the edge case
>which you've mentioned in the FS - Case 5, the Guest VM CIDR would occupy
>the entire n/w and no reservation will be possible in that n/w for that
>range. Isn't it better to use CIDR?

[Saksham] Yes the initial idea was to have IP range, but after the discussion here,  I will
change it to
Guest Vm CIDR. 
Further, its a complete admin/user choice what he specifies as the address space for Guest
It could result in no reservation also (the edge case) but as an orchestration layer, CloudStack
should not validate it.

>2. While reserving IPs for new or existing n/w, is it allowed to have
>non-contiguous IP ranges? Ex: I want to reserve -
> This in effect leads to non-contiguous Guest IP Range. In
>this case will we end up having multiple Guest CIDRs for the network?

[Saksham] The feature currently only allows a single GuestVm CIDR.

>3. After updating a guest n/w with reserved IPs, will the network be
>re-implemented? It should ideally not..

[Saksham] The network will restart when we do a change in the IP range because existing VMs
also need to 
be accommodated in the new range. So a reimplementation cannot be avoided.

>4. While updating a guest n/w with reserved IPs following checks should
>be performed:
>   4a. Only expansion is possible 
>   4b. The range is contiguous (if answer to 2 is No)
>   4c. If using default CIDR, newly defined Guest CIDR should match the
>existing one

[Saksham] Updating the guest Vm CIDR is still an open issue.

>5. In case of network offerings using external devices, user cannot
>currently define CIDR - this constraint will continue to exist for IP
>reservation too? Or will extending IP range be allowed in the existing
>n/w and then allow reservation over the new range defined?

[Saksham] Reservation will be done only after the network is implemented, instead of doing
at createNetwork level.
So networks using external devices will be allowed to have reservation once they are implemented.

>6. In the DB, is it necessary to store both Start IP-End IP along with
>guest_vm_cidr? Wouldn't effective cidr suffice since it's derived?

[Saksham] You are correct, guest_vm_cidr will suffice
>-----Original Message-----
>From: Saksham Srivastava []
>Sent: Tuesday, January 15, 2013 10:37 PM
>Subject: [DISCUSS] IP Address Reservation within a network
>Please find the  FS for the feature at
>Few of the points I want to bring for discussion:
>1) Extending the functionality to shared network
>       Should shared guest networks also allow for IP reservation considering
>the current scenario where Start IP and End IP are mandatory during
>shared guest network creation.
>2) Extending the GuestVm CIDR once a network is setup.
>       Ideally GuestVM CIDR can be extended to be equal to Guest CIDR. But
>Extending the range requires evaluation of each IP in the extended range
>whether it has been allocated or not.
>       Ping test is a primitive solution as ICMP denying hosts may not respond.
>Need suggestions on that.
>Saksham Srivastava
>-----Original Message-----
>From: Saksham Srivastava []
>Sent: Thursday, January 10, 2013 12:19 PM
>Subject: RE: [DISCUSS] IP Address Reservation within a network
>Using VLSM at the zone creation the admin can create multiple subnets
>from a parent subnet, but that is not what we are targeting at.
>CloudStack admin should not be interested to create a subnet for Non
>CloudStack hosts IMHO.
>This particular requirement is to only have a definite subnet for
>CloudStack Guest VMs and all other IPs in the parent subnet can be
>assigned to non CloudStack purposes.
>From: Kelcey Damage (BT) []
>Sent: Friday, January 04, 2013 11:56 PM
>Subject: RE: [DISCUSS] IP Address Reservation within a network
>So I see this and now wonder why do we even specify the guest CIDR at
>zone creation? Why not just use VLSM at network creation? Or some other
>instance in time controlled by the client/admin provisioning process.
>>-----Original Message-----
>>From: Saksham Srivastava []
>>Sent: Friday, January 04, 2013 9:41 AM
>>Cc: Manan Shah; Chiradeep Vittal
>>Subject: RE: [DISCUSS] IP Address Reservation within a network
>>The admin can specify the CIDR to be used for guest VMs (Guest CIDR)
>>during advanced zone creation.
>>This CIDR is used by default for the Guest Networks.
>>The proposed plan is to have a new parameter say "CS-GuestVM CIDR"
>>which will be a subset of the Guest CIDR.
>>For instance at the time of zone creation the Guest CIDR is
>>"CS-GuestVM CIDR" is specified as So the remaining IPs can
>>now be used for Non Cloudstack VMs/Physical servers.
>>The plan is to now use  only  as the CIDR for Cloudstack
>>Currently when the user wants to create a new Guest network , he
>>specifies the gateway and subnet mask.
>>The proposal is that he will have additional options to specify the
>>and end range for guest vms. The remaining IPs can then  be used for
>>Non Cloudstack vms.
>>Also the ranges will be frozen once the network is created.
>>-----Original Message-----
>>From: Chiradeep Vittal []
>>Sent: Thursday, January 03, 2013 12:59 PM
>>To: CloudStack DeveloperList
>>Cc: Manan Shah
>>Subject: Re: [DISCUSS] IP Address Reservation within a network
>>The proposed workflow seems counter-intuitive to me from an end-user
>>How about: reserve a range of *usable* ip addresses. Then the admin is
>>free to use the remainder of the range.
>>1. Is it one range or multiple?
>>2. Are there update semantics, or are the ranges frozen once the
>>network is created?
>>On 12/31/12 2:11 AM, "Saksham Srivastava"
>>>Hi all,
>>>I have started looking into this feature and would like to have the
>>>community feedback/suggestions on it.
>>>I would be sharing the FS shortly.
>>>On Saturday 22 December 2012 06:51 AM, Manan Shah wrote:
>>>> Hi,
>>>> I would like to propose a new feature for IP Reservation within a
>>>> I have created a JIRA ticket and provided the requirements at the
>>>>following location.  Please provide feedback on the requirements.
>>>> JIRA Ticket:
>>>> Requirements:
>>>> +within+a+Network
>>>> Regards,
>>>> Manan Shah

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