In Managed and Managed (No VLAN) networking modes, you must configure the system with
parameters that define how Eucalyptus will allocate and manage virtual machine networks.
These
virtual machine networks are known as security groups. The relevant parameters
are set in the
eucalyptus.conf on all machines running a CC. These parameters are:
- VNET_SUBNET
- VNET_NETMASK
- VNET_ADDRSPERNET
The CC will read VNET_SUBNET and VNET_NETMASK to construct a
range of IP addresses that are available to all security groups. This range will
then be further
divided into smaller networks of the size specified in VNET_ADDRSPERNET.
The first time an instance runs in a given security group, Eucalyptus chooses an unused
range
of IPs of size specified in VNET_ADDRSPERNET. Eucalyptus then implements this
network across all CCs. All instances that run within this given security group
obtain a specific
IP from this range.
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Tip
Ten of the IP addresses within each security group network are
reserved for Eucalyptus to use as gateway addresses, broadcast address, etc. For
example, if you
set VNET_ADDRSPERNET to 32, there will be 22 free IPs that are available for
instances running in that security group.
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In Managed mode, each security group network is assigned an additional parameter that
is used
as the VLAN tag. This parameter is added to all virtual machine traffic running
within the
security group. By default, Eucalyptus uses VLAN tags starting at 2, going to a
maximum of 4094.
The maximum is dependent on how many security group networks of the size specified
in
VNET_ADDRSPERNET fit in the network defined by VNET_SUBNET and VNET_NETMASK.
If your networking environment is already using VLANs for other reasons, Eucalyptus
supports
the definition of a smaller range of VLANs that are available to Eucalyptus. To
set this range
with a running and configured Eucalyptus installation:
- Determine the range that your cluster controllers are configured to support.
euca-describe-properties | grep cluster.maxnetworktag
euca-describe-properties | grep cluster.minnetworktag
- Define a range that is a proper subset of the above bounds.
euca-modify-property -p cloud.network.global_max_network_tag=<max_vlan_tag>
euca-modify-property -p cloud.network.global_min_network_tag=<min_vlan_tag>
