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From Hugo Trippaers <HTrippa...@schubergphilis.com>
Subject Re: Networking question
Date Tue, 07 Aug 2012 20:38:25 GMT
Hey Alena,

Thanks for the explanation, but in my case the network that I'm creating is an isolated network
without a SourceNat offering.

So it should not need have an ip allocated from the public ip table as it is isolated. It
is also not a VLAN but a 'direct' network as it is provisioned by the Nicira stack. 

I have a work around now that checks if there is a vlan defined on this network using the
vlanDao and if there is not the guest allocator is used.

Cheers,

Hugo

Sent from my iPhone

On 7 aug. 2012, at 20:14, "Alena Prokharchyk" <Alena.Prokharchyk@citrix.com> wrote:

> On 8/7/12 6:14 AM, "Hugo Trippaers" <HTrippaers@schubergphilis.com> wrote:
> 
>> Heya,
>> 
>> I'm trying to get my head around something and would welcome some
>> feedback.
>> 
>> The use case I'm currently working with is related to internal networks.
>> I have serveral use cases that call for internal networks that have no
>> connection to the outside world. Say I have a couple of webservers with
>> one nic in a sourcenat-ted network and one nic in a dedicated DB network.
>> And a couple of DB servers that are only located in the DB network. (A
>> similar scenario is where the VMs exist in an already existing VLAN or
>> bridged network using a Nicira Nvp Gateway)
>> 
>> As admin I have created a networkoffering with just DHCP, DNS and
>> UserData enabled and no other services. As a domain-admin I can create a
>> network based on that offering via the API and give it an ip range that I
>> want. When creating a VM in that network I get a message saying that I
>> can allocate an address.
>> 
>> If I create this network as a domain-admin the last step in
>> createNetwork(CreateNetworkCmd) in NetworkManagerImpl, the call to
>> createVlanAndPublicIpRange(), is skipped. This is OK as it is an internal
>> network for domain. When creating the VM the GuestNetworkGuru (line 402)
>> assumes that it should get an IP using the allocateDirectIp call. This
>> goes wrong as there are no IP's in the "public" pool for this lan.
>> 
>> I would like to change this piece in GuestNetworkGuru to check if the
>> public range is in the public ip table and if it's not use the
>> acquireGuestIpAddress call to reserve an IP.
> 
> 
> Hugo, there is a difference in how we maintain ip addresses for Isolated
> networks and Shared networks.
> 
> 1) For Isolated networks, any IP address from the CIDR defined on the
> network level, can be used for vm deployment. So whenever
> acquireGuestIpAddress is called, we:
> 
> * get the network cidr
> * figure out all ip addresses used from this cidr by existing vms - this
> info it taken from Nics table. Put these ip addresses to avoid set.
> * randomly pick up any free ip address (considering the avoid set) from
> the cidr space.
> 
> 
> 2) For Shared networks, the IP ranges are kept in user_ip_address table.
> There can be non-contiguous ip ranges - you can add every range using
> createVlanIpRange admin API. And the ip allocation algorithm is quite
> different here, as we can't just rely on the cidr and assume that all ip
> addresses from the cidr can be used as we do in Isolated network case.
> 
> Every time we have to allocate ip address from the Shared range for the
> vm, we look at the user_ip_address table and pick up any FREE ip address
> from the network. If there are no free ip addresses left, admin has to add
> more using createVlanIpRange API.
> 
> So we can't use acquireGuestIpAddress call for Shared networks.
> 
> Let me know if the explanation is clear enough, or more details are needed.
> 
> -Alena.
> 
> 
>> But as I'm not completely sure about the reasoning behind this I would
>> like some feedback on my reasoning before I break stuff in other places
>> :-)
>> 
>> Cheers,
>> 
>> Hugo
>> 
>> 
>> 
> 
> 

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