Portland: A Scalable Fault- Tolerant Layer 2 Data Center Network Fabric Radhika Niranjan Mysore, Andreas Pamboris, Nathan Farrington, Nelson Huang, Pardis Miri, Sivasankar Radhakrishnan, Vikram Subramanya, and Amin Vahdat Department of Computer Science and Engineering University of California San Diego
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Portland: A Scalable Fault-Tolerant Layer 2 Data Center Network Fabric Radhika Niranjan Mysore, Andreas Pamboris, Nathan Farrington, Nelson Huang, Pardis.
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Portland: A Scalable Fault-Tolerant Layer 2 Data Center Network Fabric
Radhika Niranjan Mysore, Andreas Pamboris, Nathan Farrington, Nelson Huang, Pardis Miri, Sivasankar
Radhakrishnan, Vikram Subramanya, and Amin Vahdat
Department of Computer Science and Engineering University of California San Diego
Background
• Emerging needs for massive scale data centers• Various design elements to achieve high
performance, scalability, fault-tolerance in such environments
Problems• VM migration support among Traditional DC networks are vulnerable; migrating VMs
change the VM’s IP address breaks pre-existing TCP connections, which results in administrative overhead for TCP connection handover among VM hosts
• Switches need to be configured before deployment
• Inefficient communication between physically distance hosts
• Forwarding loops results to inefficiency, worse yet paralysis of the network
• Physical connectivity failures interferes with existing unicast and multicast sessions
• Portland– An ethernet compatible L2 protocol to solve the
mentioned issues
A Fat Tree Network• 本論文で対象とするネットワークトポロジ• DCネットワークで汎用的に用いられてるトポロジ
Portland DesignFabric Manager
• An user process running on a dedicated machine somewhere in the network responsible for..– Assisting with ARP resolution– Fault tolerance– Multicast
• 前提– The location of the Fabric Manager is transparent for each of
the switches in the network– Fabric Manager serves as a core function in Portland;
therefore 冗長化されてる
Portland DesignPositional Pseudo MAC Address
• Virtual MAC addr which specifies the location of the host in the network• Described as pod.position.port.vmid
– Pod = pod number– Position = position within pod– Port = switch port number– VMid = virtual machine number (auto increment for each added vm, zero if not running on VM?)
1. A host is connected to an edge switch
2. The edge switch creates an address mapping table within itself for further forwarding
3. The edge switch refers to the fabric manager for the newly added host
Portland DesignProxy-based ARP
• Ethernet by default broadcast to all host in the same L2 domain -> inefficient
Portland DesignDistributed Location Discovery
• All the switches broadcast a LDP (Location Discovery Protocol) to all its port on a certain interval