Fast Path Detect And Recovery

Author	Chieh-Ting Chung
E-mail	sksksk1748@gmail.com

Memo

• SDN , Fast Path Detection and recovery

Experiment environment

• Ubuntu 18.04
• Ryu Controller 4.34
• Mininet 2.3.0d6
• Python 2.7.17

Environment Install Step

• Step 1. Install ryu controller
• Step 2. Install Mininet

  $ sudo apt install mininet

Your ~/Home/ folder should look like this

Home
├── ryu/
│   └── ryu/ ...
│       └── app/ ...
│           ├── gui_topology/
│           ├── ofctl/
│           ├── my_switch.py
│           └── ...
├── mininet/
├── ControllerCLI.py
└── ...

Start

• Step 1. Use mininet to create network topology

  $ sudo mn --topo linear,3 --mac --controller remote

• Step 2. Start Ryu Controller in ~/ryu/ryu/app

  $ sudo ryu-manager --verbose --observe-links my_switch.py

• Step 3. Open ControllerCLI

  $ sudo python ControllerCLI.py

• Step 4. At mininet

  mininet> link s2 s3 down

• Step 5. At ControllerCLI

  > linkdown

If the socket port is occupied, refer to the following example

// 查詢 Port:80 狀態 
$ sudo netstat -lpn |grep 80

//範例,PID 2779
tcp  0  0  0.0.0.0:8080  0.0.0.0:*   LISTEN  2779/python

$ sudo kill -9 2779

Topology

• 

Algorithm

• Dijkstra Algorithm

Result

• link s2 s3 down 對 Considering the remove Link Link: Port<dpid=2, port_no=3, LIVE> to Port<dpid=3, port_no=2, LIVE> 的 <dpid=2> 來說 :
  • 這裡的dpid意思就是Switch
  • New shortest_path_hubs: {1: 1, 2: 0}
    • 1: 1 意思是 S2 到 S1 有 1 個 Hub(Switch)
    • 2: 0 意思是 S2 到 S2 有 0 個 Hub(Switch)
  • New shortest_path_node: {1: 2, 2: 2}
    • 1: 2 意思是，可以 h1 到 h2
    • 2: 2 意思是，可以 h2 到 h2

Reference

• Efficient fast recovery mechanism in Software-Defined Networks: Multipath routing approach
• Demonstration of single link failure recovery using Bellman Ford and Dijikstra algorithm in SDN
• Github Project: SDNMS