SDN Programming with Go
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This document discusses SDN programming with Golang. It introduces Shukra Networks, a telecom startup developing an SDN stack focused on wide area networking and inter-AS routing. It covers network programmability and SDN architecture, using NFF-Go to decouple the forwarding and control planes, and modifying packets within user defined functions attached to a packet processing graph.
![User Defined Functions
¡ñ Attach UDF to a flow using
¡ð err := flow.SetHandler(UDF, flow1)
¡ñ Take note of the several UDF types
¡ð HandleFunction(Packet, Context)
¡ð VectorHandleFunction(PacketVector[], Context)
¡ð SeparateFunction(Packet, Context) Bool
¡ñ Packet modification takes place inside the UDF
¡ð The first parameter is the packet itself.](https://image.slidesharecdn.com/sdnprogrammingwithgo-190312042109/85/SDN-Programming-with-Go-14-320.jpg)
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SDN Programming with Go
- 1. SDN Programming with Golang 28 Feb 2019 Donaldson Tan donaldson.tan@shukra-networks.com Founder / Software Engineer
- 2. Shukra Networks ¡ñ Telecommunications startup ¡ñ Developing our own proprietary SDN stack ¡ñ Our focus is on ¡ð Wide Area Networking ¡ð inter-AS routing
- 3. Table of Content ¡ñ Network Programmability ¡ñ OSI Reference Model ¡ñ SDN Architecture ¡ñ Decoupling ¡ñ Using NFF-Go ¡ñ Packet Processing Graph ¡ñ User Defined Functions ¡ñ Packet Modification
- 4. Network Programmability ¡ñ Network Programmability is the capacity to initialise, control, change and manage network behavior dynamically via open interfaces. ¡ñ Software Defined Networking (SDN) is a specific type of network programmability that supports the separation of the control and forwarding planes via standardised interfaces. RFC 7426
- 5. Terminology ? Forwarding Plane Collection of all network devices responsible for forwarding packets. Also known as Data Plane. ? Control Plane Collection of functions that instructs network devices how to process and forward packets. ? Management Plane Collection of functions that is responsible for monitoring, configuring, and managing network devices. RFC 7426
- 6. OSI Reference Model ¡ñ The OSI paradigm describes computer networking between 2 hosts from an application developer¡¯s perspective. ¡ñ The application developer emphasises on transmitting/receiving data across the network. ¡ñ Network topology, network services, network management are an awkward fit in the OSI model.
- 7. SDN Architecture Network Services Control Plane Management Plane Forwarding Plane ¡ñ The SDN paradigm describes computer networking from a network operator¡¯s perspective. ¡ñ The network operator emphasises on managing and optimising the network for cost and reliability. ¡ñ Note: The Management Plane talks to the Forwarding Plane because it uses the Forwarding Plane to collect network statistics. Applications
- 8. Decoupling Forwarding and Control Planes ¡ñ There are many ways to access the Forwarding Plane but we will be focusing how to do it via Golang. ¡ñ Data Plane Development Kit (DPDK) ¡ð Hardware support by Intel, Marvell, Mellanox, Cavium ¡ð QEMU-Virtio also supports DPDK ¡ð NFF-Go provides Go binding to the DPDK ¡ð Install DPDK and NFF-Go separately. ¡ð Important: Register the NIC(s) with the DPDK driver and setup 1GB Huge Pages. Don¡¯t register the Management NIC.
- 9. Using NFF-Go ¡ñ import ¡°github.com/intel-go/nff-go/flow¡± ¡ñ import ¡°github.com/intel-go/nff-go/packet¡± ¡ñ A skeletal NFF-Go program consists of ¡ð A packet processing graph ¡ö A DAG consists of Entry, Transient and Exit Nodes ¡ð User Defined Functions (UDF) ¡ö UDFs may be attached to each flow ¡ö UDFs are responsible for processing individual packets, such as ¡ñ Modify packet content ¡ñ Update flow counters, program state ¡ð An optional interface for communicating with an external controller ¡ö E.g. API, RPC, RMI, XMPP ¡ö Important: Run the interface on the Management NIC.
- 11. Packet Processing Graph ¡ñ Directed Acyclic Graph (DAG), which means NO LOOPS. ¡ñ Initialise with flow.SystemInit(flow.Config{CPUList:¡±0-7¡±}) ¡ð This tells NFF-Go to reserve logical cores 0-7 exclusively. ¡ð Do not use up all the logical cores, so they may be assigned to the Go scheduler, hypervisor. ¡ð Use Go¡¯s default scheduler to run the Management Interface. ¡ñ Launch the Packet Processing Graph with flow.SystemStart()
- 12. Packet Processing Graph ¡ñ Entry Nodes are specified by ¡ð flow1, err := flow.SetReceiver( uint port) ¡ð flow1, err := flow.SetGenerator(UDF, speed, context) ¡ð flow1, err := flow.SetReader(pcap_file, n) ¡ñ Exit Nodes are specified by ¡ð flow.SetStopper(flow1) ¡ð flow.SetSender(flow1, port_number) ¡ð flow.SetWriter(flow1, pcap_filename)
- 13. Packet Processing Graph ¡ñ Transient Nodes are specified by ¡ð rejectedFlow, err := flow.SetSeparator(flow1, UDF, context) ¡ð outputFlows, err := flow.SetSplitter(flow1, UDF, num_outflows, context) ¡ð mFlow, err := flow.SetPartitioner(flow, N, M) ¡ð mergedFlow, err := flow.SetMerger(flowArrays)
- 14. User Defined Functions ¡ñ Attach UDF to a flow using ¡ð err := flow.SetHandler(UDF, flow1) ¡ñ Take note of the several UDF types ¡ð HandleFunction(Packet, Context) ¡ð VectorHandleFunction(PacketVector[], Context) ¡ð SeparateFunction(Packet, Context) Bool ¡ñ Packet modification takes place inside the UDF ¡ð The first parameter is the packet itself.
- 15. Packet Modification ¡ñ Packet headers can be read and modified with the packet data type. ¡ñ Built-in methods for generating ¡ð default packets for Ethernet, IPv4, IPv6 ¡ð ICMP/ARP requests / replies ¡ñ The more important methods are ¡ð pkt.GetIPv4NoCheck() /pkt.GetIPv6NoCheck() ¡ð pkt.GetTCPNoCheck() ¡ð pkt.GetUDPNoCheck() ¡ñ These methods return the packet¡¯s relevant header which you may rewrite directly. ¡ñ Next slides show the header format for IPv4, IPv6, TCP and UDP.
- 16. Packet Modification ¡ñ IPv4 Header ¡ñ IPv6 Header
- 17. Packet Modification ¡ñ TCP Header ¡ñ UDP Header
- 18. -The End-
- 19. But how do I separate the forwarding and control planes in the OSI model? You don¡¯t!
- 20. Open vSwitch VM1 VM2 Open vSwitch VM3 VM4 Host 1 Host 2 Physical Network VXLAN Tunnel What is SDN used for? ¡ñ Network Virtualisation. E.g. Amazon¡¯s VPC is actually a L2VPN distributed across multiple hypervisors. VPC
- 21. What is SDN used for? ¡ñ High Performance Cloud Network Appliances ¡ñ Security ¡ð DDoS Filtering ¡ð Deep Packet Inspection
- 22. What is SDN used for? ¡ñ Custom Traffic Engineering ¡ð Network telemetry ¡ð Load Balancing ¡ð Intelligent Routing ¡ð Congestion Control ¡ð Traffic Shaping ¡ð QoS