Bài giảng Các giao thức định tuyến: SDN (Software defined network)

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Bài giảng Các giao thức định tuyến: SDN (Software defined network). Chương này cung cấp cho học viên những nội dung gồm: Các “mặt phẳng” trong mạng; kế hoạch dữ liệu; kế hoạch kiểm soát; kế hoạch quản lý; mạng SDN; ứng dụng SDN - ảo hóa mạng; chương trình điều khiển;... Mời các bạn cùng tham khảo chi tiết nội dung bài giảng!

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Nội dung Text: Bài giảng Các giao thức định tuyến: SDN (Software defined network)

SDN- Software Defined Network
Các “mặt phẳng” trong mạng •  Data plane: processing and delivery of packets with local forwarding state –  Forwarding state + packet header à forwarding decision –  Filtering, buffering, scheduling •  Control plane: computing the forwarding state in routers –  Determines how and where packets are forwarded –  Routing, traffic engineering, failure detection/recovery, ... •  Management plane: configuring and tuning the network –  Traffic engineering, ACL config, device provisioning, ...
Data plan Data Plane Streaming algorithms on packets –  Matching on some header bits –  Perform some actions Example: IP Forwarding 1.2.3.4 1.2.3.7 1.2.3.156 5.6.7.8 5.6.7.9 host host ... host host host ... host LAN 1 LAN 2 router router router WAN WAN 1.2.3.0/24 5.6.7.0/24 11 forwarding table
Control plan •  Compute paths the packets will follow –  Populate forwarding tables –  Traditionally, a distributed protocol •  Example: Link-state routing (OSPF, IS-IS) –  Flood the entire topology to all nodes –  Each node computes shortest paths –  Dijkstra’s algorithm
Control plan 1.  Figure out which routers and links are present. 2.  Run Dijkstra’s algorithm to find shortest paths. “If a packet is going to B, then send it to output 3” Data 2 1 “If , send to 3” 3
Management plan Management Plane Traffic Engineering: setting the weights –  Inversely proportional to link capacity? –  Proportional to propagation delay? –  Network-wide optimization based on traffic? 2 3 1 1 3 2 3 1 5 4 3 15
Time scales Timescales Data Control Management Time- Packet Event (10 Human (min scale (nsec) msec to sec) to hours) Location Linecard Router Humans or hardware software scripts 9
Data plan vs Control plan Data and Control Planes control plane data plane Processor Line card Line card Line card Switching Line card Fabric Line card Line card 10
SDN Network •  A network in which the control plane is physically separate from the data plane. –  Control plan of conventional routers are moved up to centralized control programs •  A single (logically centralized) control plane controls several forwarding devices
SDN network SoJware Deﬁned Network (SDN) Control Program A Control Program B Network OS Packet Forwarding Packet Forwarding Packet Packet Forwarding Forwarding Packet Forwarding 26
Application of SDN: Network virtualisation •  Consider a multi-tenant datacenter –  Want to allow each tenant to specify virtual topology –  This defines their individual policies and requirements •  Datacenter’s network hypervisor compiles these virtual topologies into set of switch configurations –  Takes 1000s of individual tenant virtual topologies –  Computes configurations to implement all simultaneously •  This is what people are paying money for.... –  Enabled by SDN︎s ability to virtualize the network
Control program •  Control program operates on view of network – Input: global network view (graph/database) – Output: configuration of each network device •  Control program is not a distributed system –  Abstraction hides details of distributed state
Network OS (on Controller) •  Network OS: creates a consistent, up-to-date network view –  Runs on servers (controllers) in the network –  ONOS, NOX, ONIX, Floodlight, Trema, OpenDaylight, HyperFlow, Kandoo, Beehive, Beacon, Maestro, ... + more •  Uses forwarding abstraction to: –  Get state information from forwarding elements –  Give control directives to forwarding elements
OpenFlow basics OpenFlow Basics Control Program A Control Program B Network OS OpenFlow Protocol Ethernet Switch Control Path OpenFlow Data Path (Hardware) 35
OpenFlow basics •  Means of communication between controller and switch •  OpenFlow enables network controllers to determine the path of network packets across a network of switches •  OpenFlow allows remote administration of a layer 3 switch's packet forwarding tables, by adding, modifying and removing packet matching rules and actions. •  The OpenFlow uses TCP for encapsulating Openflow packets. Controllers should listen on TCP port 6653 for switches that want to set up a connection.
OpenFlow basics OpenFlow Basics Control Program A Control Program B Network OS If header = p, send to port 4 Packet If header = q, overwrite header with r, Forwarding add header s, and send to ports 5,6 If header = ?, send to me Flow Packet Table(s) Forwarding Packet Forwarding 36
Primitives Primitives Match arbitrary bits in headers: Header Data Match: 1000x01xx0101001x –  Match on any header, or new header –  Allows any flow granularity Action –  Forward to port(s), drop, send to controller –  Overwrite header with mask, push or pop –  Forward at specific bit-rate
OpenFlow Rules OpenFlow Rules Exploit the flow table in switches, routers, and chipsets Flow 1. Rule AcNon StaNsNcs (exact & wildcard) Flow 2. Rule AcNon StaNsNcs (exact & wildcard) Flow 3. Rule AcNon StaNsNcs (exact & wildcard) Rule Flow N. Default AcNon StaNsNcs (exact & wildcard)
Testbed •  Network emulation tools –  Mininet –  Openvswitch •  SDN Controller (Network OS) –  Opendaylight, Floodlight, POX, ONOS….
Bài tập •  Cài đặt thử nghiệm mạng SDN –  Sử dụng Mininet mô phỏng mạng các switch –  Sử dụng 1 controller: Opendaylight, Floodlight, ONOS, POX –  Xây dựng ứng dụng người dùng cho phép định tuyến dữ liệu giữa 2 điểm nguồn đích theo một tuyến đường nhất định. •  Ứng dụng cho phép nhập vào switch nguồn, đích và danh tuyến đường. Ví dụ: A ->B: A1-A2-A3… B •  Yêu cầu các chuyển mach phải được cấu hình để vận chuyển dữ liệu đúng theo tuyến đường trên.