Software Defined Networking and the design of OpenFlow switches

Transcription

1 Software Defined Networking and the design of OpenFlow switches Paolo Giaccone Notes for the class on Packet Switch Architectures Politecnico di Torino December 2015

2 Outline 1 Introduction to SDN 2 OpenFlow 3 Design of OpenFlow switches Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

3 Introduction to SDN Section 1 Introduction to SDN Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

4 Introduction to SDN Network Architecture Control plane how to handle traffic (e.g. routing) Data plane forward the traffic based on the control plane decision Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

5 Introduction to SDN Traditional networks Internet architecture vertically integrated control and data planes within each device control plane distributed across the switches/routers complex and hard to manage due to distributed control plane difficult to understand the state of the network and its history vendor-specific commands to manage switches/routers Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

6 Introduction to SDN Software Defined Networking (SDN) Emerging networking paradigm Separation between control and data plane routers and switches just acting as forwarding elements Flow-based forwarding decision instead of destination-based forwarding flow definition: a set of packet field values acting as a match rule and a set of actions to operate on all packets belonging to the same flow unify the behavior of routers, switches, firewalls, load-balancers, traffic shapers, etc. Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

7 Introduction to SDN Software Defined Networking (SDN) Logical centralization of the control plane unique abstract view of the network state (e.g. topology) control logic moved to an external entity SDN controller or Network Operating System (NOS) Network programmability network applications run on the SDN controller similar to computer applications running on computer operating system standard or ad-hoc languages Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

8 Introduction to SDN SDN controller software platform running on commodity servers logically centralized for scalability and reliability reasons, can be distributed in different servers VERSION 2.01 open-source examples: NOX, POX, Ryu, ONOS, OpenDaylight, etc. centralization implied a physically issue we will return to later on success. Google, for example, has d helping the company to improve ope nificantly reduce costs [8]. VMwa Network(Applica4on(s)( SDN momentum was strong enou book, Yahoo, Microsoft, Verizon, a Open northbound API Open Networking Foundation (ON Controller(Pla+orm( of promotion and adoption of SD Open southbound API development. As the initial conce were addressed [11] in particu and evolved from an academic network to interconnect its data This production network has been Network Infrastructure platform, NSX [12], is another exam solution that delivers a fully funct Fig. 1. Simplified view of an SDN architecture. provisioned independent of the unde Image taken from [Kr15] entirely based around SDN principl world s largest IT companies (fro Giaccone (Politecnico di Torino) network operating system SDN and 1 ), OF simplifying switchespolicy enforcement manufacturers Dec. to2015 cloud providers 8 / 23 a Data forwarding elements (e.g., OpenFlow switches)

9 Introduction to SDN SDN controller interfaces Northbound Interface (NBI) API APIs available to application developers CLI (Command Line Interface), GUI (Graphical User Interface), REST APIs e.g. curl abstracts the low-level instructions to program forwarding devices needed to develop the network applications with any programming language Southbound Interface (SBI) API protocol to access the switches and to send them commands enables the interaction between control and data plane Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

10 Introduction to SDN Adoption of SDN Google uses SDN in WAN to interconnect data centers within the data center network operators and ISP are also considering to move to SDN networks next generation 5G networks are based on SDN in all the layers Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

11 OpenFlow Section 2 OpenFlow Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

12 OpenFlow OpenFlow initial idea proposed at Stanford University in 2006 definition by Open Networking Foundation (ONF) ONS promotes the adoption of SDN through open standards OpenFlow 1.0 released on Dec 2009 OpenFlow released on Mar 2015 defines the protocol adopted in the southbound interface (SBI) Image taken from [OF15] Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

13 OpenFlow OpenFlow messages transported on TLS or TCP connections Packet-in from the switch to the controller to transfer the control of a received packet to the controller carries a copy of the packet (possibly, only the header) generated by default in case of forwarding table misses Packet-out from the controller to the switch to send packets out of a specified port on the switch carries the full packet or an ID buffer of the switch Flow-mod from the controller to the switch to modify the flow tables carries the match-action rule to install in the switch Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

14 OpenFlow OpenFlow example Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

15 OpenFlow Example of flow tables Ethernet switch (e.g. to reach 68:a8:6d:00:81:42) Switch MAC MAC Eth IP IP TCP TCP Action Port src dst type src dst src port dst port * * 68:a8:6d:00:81:42 * * * * * Forward P1 IP router (e.g. direct delivery on /24) Switch MAC MAC Eth IP IP TCP TCP Action Port src dst type src dst src port dst port * * * 0x * * * * Forward P2 Firewall (e.g. block BitTorrent from all Politecnico s hosts) Switch MAC MAC Eth IP IP TCP TCP Action Port src dst type src dst src port dst port * * * 0x * * * 6969 Drop Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

16 OpenFlow OpenFlow fields Version Fields OpenFlow OpenFlow OpenFlow Examples: switch input port, Ethernet frame type and addresses, VLAN id and priority, IP DSCP/ECN flags and protocol and addresses, TCP ports and flags, UDP ports, ICMP type and code, ARP op code and addresses, MPLS labels and flags, metadata passed between tables. Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

17 Design of OpenFlow switches Section 3 Design of OpenFlow switches Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

18 Design of OpenFlow switches OpenFlow switches Flow (or Forwarding) Tables Each rule is a match-action pair Match binary exact match (0,1) ternary match (0,1,*) Action drop, forward, modify, goto another table Flexibile Enables to implement routers, switches, firewalls, load balancers, traffic shapers, etc. Packet processing OpenFlow Switch Specification Version Introduction Through a sequence of flow tables This document describes the requirements of an OpenFlow Logical Switch. Additional informatio describing OpenFlow and Software Defined Networking is available on the Open Networking Foundatio website ( This specification covers the components and the bas functions of the switch, and the OpenFlow switch protocol to manage an OpenFlow switch from remote OpenFlow controller. Port Port 2 Switch Components Controller OpenFlow Channel Flow Table Controller Protocol OpenFlow Channel Control Channel Flow Table Pipeline OpenFlow Switch Group Table Datapath Flow Table Meter Table Port Port Figure 1: Main components of an OpenFlow switch. Image taken from [OF15] An OpenFlow Logical Switch consists of one or more flow tables and a group table, which perform packe lookups and forwarding, and one or more OpenFlow channels to an external controller (Figure 1). Th Giaccone (Politecnico di Torino) SDN and switch OF switches communicates with the controller and the controller manages Dec. the switch 2015via the OpenFlow 18 / 23switc

19 Design of OpenFlow switches Packet processing within each flow table Matching based OpenFlow Switch onlyspecification the header fields Version Action Set Pipeline Fields Packet Find highest priority matching flow entry Match Extract header fields flow entry flow entry flow entry flow entry flow entry table miss flow entry Apply Instructions Apply-actions {list of actions} modify packet update match fields update pipeline fields if output or group clone packet Flow Table Clear-actions empty action set Write-actions {set of actions} merge in action set Goto-table {table-id} Flow Table Execute Action Set Packet clones Egress 5.5 Instructions Figure 4: Matching and Instruction exectution in a flow table. Image taken from [OF15] Each flow entry contains a set of instructions that are executed when a packet matches the entry. These instructions result in changes to the packet, action set and/or pipeline processing (see Figure 4). Giaccone (Politecnico A switch di Torino) is not required to support all SDN instruction and OFtypes, switches just those marked Required Instruction Dec / 23

20 Design of OpenFlow switches Table 1 perform Implementation on NetFPGA Implementation in FPGA used as reference model for hardware architecture of any OpenFlow switch Image taken from [Na08] Figure 5: The OpenFlow switch pipeline is similar to the IPv4 Reference Router Pipeline. number o 7daysdu over 9000 tive flow EE/CS n switch s Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

21 Design of OpenFlow switches Programmable packet processing New programmable architecture compatible with any packet processing Compatible with OpenFlow Switch State (metadata) Logical Stage 1 Statistics State Logical Stage N Packets Input Channels 1 K... Header Prog. Parser Payload... Select... Match Tables VLIW Action... New Header Recombine Configurable Output Queues K Packets Output Channels Physical Stage 1 Physical Stage 2 (a) RMT model as a sequence of logical Match-Action stages. Image taken from [Bo13] Physical Stage M Giaccone Logical (Politecnico Stage 1 di Torino) SDN and OF switches Dec / 23 H Action I Src 1 Src 2 Src 3 Action Unit

22 Design of OpenFlow switches New OpenFlow-related switch designs OpenState state machine within each switch delegates some control from the controller to the switch refer to [BC14] P4 protocol-independent packet processors new programming language internal state machines within each switch possible candidate for OpenFlow 2.0 refer to [Bo14] Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23

23 Design of OpenFlow switches Bibliography BC14 Bianchi, Giuseppe, et al. OpenState: programming platform-independent stateful openflow applications inside the switch. ACM SIGCOMM Computer Communication Review 44.2 (2014): Bo13 Bosshart, Pat, et al. Forwarding metamorphosis: Fast programmable match-action processing in hardware for SDN. ACM SIGCOMM Computer Communication Review. Vol. 43. No. 4. ACM, Bo14 Bosshart, Pat, et al. P4: Programming protocol-independent packet processors. ACM SIGCOMM Computer Communication Review 44.3 (2014): Kr15 Kreutz, Diego, et al. Software-defined networking: A comprehensive survey. Proceedings of the IEEE, (2015): Na08 Naous, Jad, et al. Implementing an OpenFlow switch on the NetFPGA platform. Proceedings of the 4th ACM/IEEE Symposium on Architectures for Networking and Communications Systems. ACM, OF15 OpenFlow Switch Specification, Version 1.5.1, Open Networking Foundation, March 2015 Giaccone (Politecnico di Torino) SDN and OF switches Dec / 23