Author: Antxon Gonzalez

VM networks are Virtual Networks which that use a VLAN tag on top of the Hypervisors Networks Interfaces Hypervisor's Network Interfaces on the physical Network.

The Physical Network Interfaces belong to a Network Service Type (NST), which identifies the Network Segment the Interface network segment that the interface is connected to.

To understand Abiquo Cloud networking, you need to take into account these concepts first.

Racks

Before you add an a Physical Machine to a Datacenter, you need to create the Rack it will belong to.

A rack is a logical set of Physcal Physical Machines providing the same level of compute level service.

Each rack also defines also a VLAN pool for all the physical machines inside the rack.

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Network Service Type

Every time you add a Physical Machine, you must choose its Rack and specify the Network Service Type (NST) its Network Interfaces network interfaces are connected to.

A NST is a set of Interfaces interfaces providing the same network service level. You may think that each one NST is a Network Segment different from the othersdifferent network segment.

VLANs inside a NST have the same meaning for interfaces in the same rack, while it may VLANs will be different for Interfaces interfaces in different NSTs or Racks.

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Cloud networks

Cloud Networks in Abiquo are defined by its their type, NST and VLAN tag. This forces means that all VMs using them to run in Hypervisors a network will run on hypervisors with NICs of the corresponding NST.

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• Private: Bound to the Virtual Datacenter (VDC) they were created in.
  Their The VLAN tag is taken from the VLAN pool of a rack automatically, bounding the network workload to it.
  
  
• External: Bound to a Datacenter and an Enterprise.
  This means that the network VLAN tag has the same meaning for all racks in the Datacenter.
  
  
• Public: Bound to a Datacenter only.
  They are similar to external networks, but may be used by different enterprises at the same timemore than one enterprise may use them.

Private networks are bound to the racks rack they were defined in, and their VLAN tags have no meaning outside itthis rack. This in fact bounds VDCs means that VDCs are bound to the rack their privates private networks are defined in.

External and public networks instead have the same meaning can be used in all the racks in a datacenter. Their VLAN tag tags must be defined in the NST infrastructure before defining you define them inside Abiquo.

VMs in the same enterprise may talk to each other communicate through public an and external networks, or private networks is they belong to the same VDC.

The only way for VMs in different enterprises to talk to each other communicate is through a public network instead.

DHCP

There are two different approaches to get DHCP working on in your environment: Regular DHCP infrastructure or the Abiquo DNSMasq networking solution.

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DHCP may require a Relay network infrastructure to deal with all networks depending on their number,  while the DNSMasq solution has no limits to the number of interfaces the server may be listening to.

Additionally, DHCP requires an OMAPI capable server, as this is the protocol that Abiquo will use to manage the leases for the network environment.