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Data Center Ethernet

Data Center Ethernet. M. Keshtgary. Overview. Residential vs. Data Center Ethernet Review of Ethernet Addresses, devices, speeds , algorithms Enhancements to Spanning Tree Protocol Virtual LANs Data Center Bridging Extensions. Residential vs. Data Center Ethernet.

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Data Center Ethernet

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  1. Data CenterEthernet M. Keshtgary

  2. Overview • Residential vs. Data Center Ethernet • Review of Ethernet Addresses, devices, speeds, algorithms • Enhancements to Spanning Tree Protocol • Virtual LANs • Data Center Bridging Extensions

  3. Residential vs. Data Center Ethernet

  4. IEEE 802 Address Format

  5. Ethernet vs IEEE 802.3 • The source address is always a unicast (single node) address, while the destination address may be unicast, multicast (group), or broadcast (all nodes). • In Ethernet frames, the 2-byte field following the source address is a type field. This field specifies the upper-layer protocol to receive the data after Ethernet processing is complete. • In IEEE 802.3 frames, the 2-byte field following the source address is a length field, which indicates the number of bytes of data that follow this field • In IEEE 802.3, the upper-layer protocol must be defined within the data portion of the frame, if at all

  6. Names, IDs, Locators

  7. Interconnection Devices

  8. Interconnection Devices

  9. Ethernet Speeds

  10. Link Aggregation Control Protocol (LACP)

  11. Spanning Tree Algorithm

  12. Problems with STP • A topology change can result in 1 minute of traffic loss with STP and All TCP connections break • Does not support VLAN • Solution is Rapid Spanning Tree Protocol (RSTP)

  13. Rapid Spanning Tree Protocol (RSTP) • IEEE 802.1w-2001 incorporated in IEEE 802.1D-2004 • One tree for all VLANs => Common spanning tree • Many trees => Multiple spanning tree (MST) protocol • IEEE 802.1s-2002 incorporated in IEEE 802.1Q-2005 • One or more VLANs per tree.

  14. rstp • RSTP fixes STP problems by: • 1. Being time + event driven instead of just event driven • Once converged, STP sends BPDUs only on change • RSTP sends Hellos every 2 seconds. Quick failure detection. • 2. Differentiating between edge ports (servers) and non-edge ports (switches). No loops ever on edge ports • 3. Differentiating between point-to-point links (full duplex) and shared links (half-duplex). RSTP only on full-duplex

  15. RSTP (Cont) • Merging three port states (Disabled, blocking, listening) in to one (discarding). • 5. Adding 4 new flags in BPDU, that allow sending a proposal and accepting or not accepting the received proposal • RSTP is backward compatible with STP. RSTP-unaware bridge drop RSTP and RSTP is

  16. RSTP Example

  17. MSTP (Multiple Spanning Tree)

  18. IS-IS Protocol • Intermediate System to Intermediate System (IS-IS) is a routing protocol designed to move information efficiently within a computer network, a group of physically connected computers or similar devices. • It accomplishes this by determining the best route for datagrams through a packet-switched network. • The protocol was defined in ISO/IEC 10589:2002 as an international standard within the Open Systems Interconnection (OSI) reference design • IS-IS Protocol is link state

  19. IS-IS Protocol

  20. Shortest Path Bridging

  21. What is a LAN?

  22. What is a Virtual LAN

  23. Virtual LAN

  24. Types of Virtual LANs

  25. IEEE 802.1Q-2011 Tag

  26. Link Layer Discovery Protocol (LLDP)

  27. Data Center Bridging

  28. Ethernet Flow Control: Pause Frame

  29. Priority-based Flow Control (PFC) • Ref: J. L. White, “Technical Overview of Data Center Networks,” SNIA, 2013, http://www.snia.org/sites/default/education/tutorials/2012/fall/networking/JosephWhite_Technical%20Overview%20of%20Data%20Center%20Networks.pdf

  30. Enhanced Transmission Selection

  31. ETS (Cont)

  32. Quantized Congestion Notification (QCN) Ref: I. Pepelnjak, “DCB Congestion Notification (802.1Qau),” http://blog.ipspace.net/2010/11/data-center-bridging-dcb-congestion.html

  33. DCBX • Data Center Bridging eXchange, IEEE 802.1Qaz-2011 • Uses LLDP to negotiate quality metrics and capabilities for Priority-based Flow Control, Enhanced Transmission Selection, and Quantized Congestion Notification • New TLV’s • Priority group definition • Group bandwidth allocation • PFC enablement per priority • QCN enablement • DCB protocol profiles

  34. Summary • Ethernet’s use of IDs as addresses makes it very easy to move systems in the data center => Keep traffic on the same Ethernet • Spanning tree is wasteful of resources and slow. • Ethernet now uses shortest path bridging (similar to OSPF) • VLANs allow different non-trusting entities to share an Ethernet network • Data center bridging extensions reduce the packet loss by enhanced transmission selection and Priority-based flow control

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