Implementation note today a nodes ip address must be

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Implementation Note: Today, a node’s IP address must be statically assigned, although it can be served by DHCP. This limitation does not seem to be fundamental, and is likely to be removed in the near future. There is usually a one-to-one mapping between nodes and physical machines, but this is not a requirement. It is possible for a node to be implemented inside 8
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a virtual machine, perhaps even one that migrates from one physical machine to another, as might be the case on a cluster. In such a situation, however, a non- shared IP address must be assigned to the node. As a practical matter, changing the IP address assigned to a node is expected to be an infrequent operation. There is no requirement that all nodes be of the same machine architecture, although the current implementation is limited to x86 processors. The architecture assumes that there is a means by which PLC can remotely reboot a node. The preferred implementation is an on-machine reboot capability (e.g., HP’s Lights-Out product), although other implementations are possible. The mechanism should also support console logging. A node boots with three pieces of state in a persistent, write-protected, store: a bootfile , a network configuration file named plnode.txt , and a public key for PLC. All three pieces of information are created through an offline process involving the node owner and PLC, and installed in the node by the owner. The bootfile is an executable image that the node is configured to run whenever it boots. This program causes the node to interact with PLC to download all neces- sary software modules (see Section 4.8). plnode.txt is a node-specific text file that is read by the executable booted from the bootfile . It gives various attributes for the node, including its node id , DNS name, and IP address, along with a unique nodekey generated by PLC and assigned to the node. The following is an example plnode.txt file: IP METHOD = ”dhcp” IP ADDRESS = ”128.112.139.71” HOST NAME = ”planetlab1.cs.foo.edu” NET DEV = ”00:06:5B:EC:33:BB” NODE KEY = ”79efbe871722771675de604a2...” NODE ID = ”121” Implementation Note: Today, the bootfile is available on a CD, and plnode.txt is available on either a floppy or USB device. In general, they could be combined on a single device. The node uses the nodekey from plnode.txt during the boot process to authen- ticate itself to PLC (see Section 4.8). PLC trusts that the node is physically secure, corresponding to edge (4) in Figure 1. 4.2 Virtual Machine A virtual machine (VM) is an execution environment in which a slice runs on a par- ticular node. VMs are typically implemented by a virtual machine monitor (VMM) 9
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running on the node, but this is not a requirement. Whatever the implementation, the architecture makes the following assumptions about the VMs that a node hosts: VMs are isolated from each other, such that the resources consumed by one VM do not unduly effect the perfor- mance of another VM; one VM cannot eavesdrop on network traffic to or from another VM; and one VM cannot access objects (e.g., files, ports, processes) belonging
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