Notes

Modes of eucalyptus

1.Managed
▪ Most feature rich mode offered by Eucalyptus. – VM network isolation, security group, elastic IP, metadata service.
▪ In this mode, the administrator defines a large network (usually private and non-routable) from which VM instances will draw their IP addresses.
▪ CC maintains a DHCP server with static mappings for each VM created and allocate the right IPs at the time of requesting an NC.
▪ Managed mode implements ‘security groups’ for ingress filtering and isolation of VMs.
▪ The user specifies a security group to which the new VM should be associated with, at the time of requesting a new VM.
▪ CC allocates a subset of the entire range of IPs to each security group in such a way that all the VMs
be a part of the same security group use IPs from the same subset.
▪ VMsin different security groups are isolated by using a Virtual LAN (VLAN)
▪ Two IP addresses are assigned to each VM – Public & Private IP address.
▪ The user can define ingress filtering rules at the ‘security group’ level.
▪ The administrator can specify a pool of public IP addresses that users may allocate at booting time or at run-time. This functionality is similar to ‘elastic IPs’ of AWS.

2.Managed - No VLAN
▪ This mode is identical to MANAGED mode in terms of features (dynamic IPs and security groups), but does not provide VM network isolation using VLAN.
▪ Root user on one VM can snoop into other VMs on the same network on layer 2.
▪ Eucalyptus administrators who want dynamic assignable IPs and the security groups, but are not in a position to run on a network that allows VLAN tagged packets or those who do not have a need for VM network isolation can use this mode.

3. System
▪ Simplest mode but with least features.
▪ In System mode, CC generates and assigns a random MAC address to the VM instance while requesting NC to bring up the VM.
▪ NC attaches the VM instance’s virtual NIC to the physical NIC on the node through a bridge.
▪ This mode requires that the Nodes are connected to the enterprise network directly.
▪ VMs obtain an IP address using DHCP, just as physical machines on the network do.
▪ This mode is very easy to setup as it does not have any additional prerequisites in terms of networking, except for a running DHCP server on enterprise network.
▪ This mode of networking is similar to “Bridged Networking” that hypervisors like VMware, VirtualBox etc. offer or like “tap” networking offered by KVM/Qemu.

4. Static
▪ Static mode offers the Eucalyptus administrator more control over VM IP address assignment than System mode does.
▪ In this mode, the administrator configures Eucalyptus with a ‘map’ of MAC address/IP Address pairs on CC.
▪ Before requesting NC to start the VM, CC sets up a static entry within a Eucalyptus controlled DHCP
server, takes the next free MAC/IP pair, and passes on to NC, which attaches the virtual NIC of the
instance to the physical NIC of the Node through a bridge similar to how it is handled in ‘System’ mode.
▪ This mode is useful for administrators who have a pool of MAC/IP addresses that they wish to always assign to their VMs without relying on the DHCP server running in the enterprise network.
▪ Note – Running Eucalyptus in System or Static mode disables some of the following key functionalities
that would make an enterprise deployment more manageable:
– Ingressfiltering for the instances ( Security Groups )
– User Controlled dynamic assignment of IPs to instances ( Elastic IPs )
– Isolation of network traffic between instances VMs
– Availability of the meta-data service.