###### tags: `Meetup`、`Co-writing`
# CNTUG meetup #24

[TOC]

## Session 1. OpenvSwitch 深入淺出

http://www.openvswitch.org/


Openflow
---
- Maintained by Open Networking Foundation (ONF)
- The first standard communication interface defined network...

Format
---
- Rule (比對規則): Switch Port, Layer 2 Header, Layer 3 Header, Layer 4 Header
- Action (比對到規則後要做的事)
- Forward packet to ports
- Encapsulate and forward to controller
- Modify fields (修改 Header 任何欄位)
- Normal Pipeline
- Extension (現實環境可能有些狀況是 OpenFlow 預設沒有支援的，可以寫 Extension 來擴充功能)
- Stats

Open vSwitch
---
- Need to prepare all flow rules
- without linux kernel (mostly)
- Openflow controller
- Program your logic
- CLI
- Difficult to maintain all logics
> OpenFlow Rule 雖然很漂亮，但是很難下，例如：在一般 Linux Kernel 底下，NAT 直接用 iptables 就可以完成，但是如果改用 OpenFlow Rule，就必須下一大堆 Rule (除了 ARP Rule 之外還必須修改 Src IP, Dst IP)，增加管理上及實作上的複雜度。

Other funcations
---
- Linux
- Tunneling
- GRE/VXLAN/GRE/STTNVGRE
- iptables extension
- nfqueue .. etc
- 802.1q VLAN
- Link Aggregation with/without LACP
- QoS
- Traffic Shaping
- Socket Applications
- VPN, other networking functions.
> Linux Kernel (iptables) 能做到的功能比 Open vSwitch 還要多出很多，且Linux 社群比 Open vSwitch 社群還要龐大更多，因此建議根據使用情境，來決定是否採用 Open vSwitch 或是使用 Linux Kernel 就可以了。

Kuberbetes & OVS
---
- Kubernetes & Networking
- Pod communication
- Pod to Pod
- Pod to WAN
- Service
- ClusterIP
- NodePort
- Network Policy
- Kubernetes 不實作，交給CNI
- CNI Flannel
- Linux Bridge
- ARP Table
- Routing Table
- Iptables
- Iptables
- Challenge
- Pod to Pod
- Same Node
- Different Node
- Overlay?
- Pod to WAN
- NAT
- Kube-proxy (service)
- Monitor service object
- Create/Update/Remove rules
- Translate policy to OpenFlow rules and apply to all switches.
- NetworkPolicy
- Monitor network...
- Projects
- K-vswitch https://github.com/k-vswitch/k-vswitch 
- SONA-CNI https://github.com/sonaproject/sona-cni https://wiki.onosproject.org/display/ONOS/SONA-CNI+Installation 
- Ovn-kubernetes
- ...etc

Why OVS?
---
- Networking performance?
- Open vSwitch + DPDK (Kernal Bypass)
- Hardware offloading
- Service Chain?
- Similar to Service Mesh
- Service Mesh 大多都是用 iptables 來完成，iptable rules 數量一大，效率就降低(因為需要一條條比對)，且極難維護
- Rewrite packets header
- Redirect packets within different Pods
- Networking Traffic Monitor?
- Latency
- Counters

> 複雜度大於好處，未必需要導入 Kubernetes

Do I Need it?
---

### One

- Learn how system works
- Computing/Storage/Networking
- Linux (將基本LINUX功夫學好，這些底層概念都可以帶著走)
- Increase your value (你和其他人的價值差別在哪)
- Don't rely on Framework or Tools
- Helm/Operator framework ...etc
- Never be the Yaml Engineer

> Don't be YAML engineer! 不懂底下如何運作，只知道如何寫 YAML 就可以 work

Q&A
---
SR-IOV
https://github.com/feiskyer/sdn-handbook/blob/master/linux/sr-iov.md

## Session 2. Stratum - 讓你擁有真正的SDN

- Challenge:
- Challenge:
- Challenge: Handling Migration
- Widespread, greenfield adoption of new technology is not feasible
- Types of Migration
- Need interfaces, models and operations to be consistent to allow incremental adoption along these axes
- Wanted
- New control interface with:
- Abstraction for different types of switching chips
- Well defined interfaces and behavior
- Extensibility
- Common models for configuation and monitoring
- Common interafces for operations
- Common platform abstraction
- Open source switch stack

P4 (Programming Protocol-indenpendent Packet Processors)
---
https://p4.org/

- Domain-specific language to formally...
- Example: https://github.com/p4lang/behavioral-model/blob/master/mininet/simple_router.p4

P4Runtime overview
---
- API for runtime control of P4-defined switches
- Community-developed (p4.org API WG)
- Initial contribution by Google and Barefoot
- RC of version 1.0 available: https://p4.org/specs/
- gRPC/protobuf-based API definition
- P4 program-independent
- Enables filed-reconfigurability

Though P4Runtime are great, but...
---
- Missing
- Configuration
- Monitoring
- Operations

Enhanced Configuration
---
- Configuration and Management
- Declarative configuration
- Streaming telemetry
- Model-driven management and operations
- gNMI - network management interafce
- gNOI - network operations interface
- Vendor-neutral data models

> Google (seed code) + ONF (and community) = stratum

Vision
---
- Stratum supports multiple silicon products
- Stratum runs on many platforms
- Widely deployed in production SDN fabrics
- Enables P4Runtime and OpenConfig in the industry


{%pdf https://www.opennetworking.org/wp-content/uploads/2019/08/Day1-Brian-OConnor-NG-SDN-Stratum.pdf %}

{%pdf https://www.opennetworking.org/wp-content/uploads/2018/12/Stratum_-An-Overview.pdf %}


- Stratum Use Cases
- Cloud SDN Fabric
- CORD: 5G Mobile & More
- Thick Switch/Router




Stratum Implementation Details
---
- Implements P4Runtime, gNMI, and gNOI services
- Controlled locally or remotely using gRPC
- Written in C++11
- Runs as a Linux process in user space
- Can be distributed with ONL
- Built using Bazel

Project Status
---
- Reference platforms from 2 ASIC vendors and 6 platform vendors

Getting Involved
---
- https://github.com/stratum/stratum