Computer Networking and Applications
Control Plane (Traditionally…)
• Internet network layer: historically has been implemented via distributed, per-router approach
– monolithic router contains switching hardware, runs proprietary implementation of Internet standard protocols (IP, RIP, IS-IS, OSPF, BGP) in proprietary router OS (e.g., Cisco IOS)
Copyright By PowCoder代写 加微信 powcoder
– different “middleboxes” for different network layer functions: firewalls, load balancers, NAT boxes, ..
Software defined networking (SDN)
• ~2005: renewed interest in rethinking network control plane
Computer Networking and Applications
Traffic engineering: difficult traditional routing
Q: what if network operator wants u-to-z traffic to flow along uvwz, x- to-z traffic to flow xwyz?
Computer Networking and Applications
Traffic engineering: difficult
Q: what if network operator wants to split u-to-z traffic along uvwz and uxyz (load balancing)?
Computer Networking and Applications
Traffic engineering: difficult
Q: what if w wants to route blue and red traffic differently?
Network Layer: Control Plane
Computer Networking and Applications
Software defined ne…tworking (SDN)
4. programmable control applications
3. control plane functions
access load external to data-plane
Remote Controller
control plane
data plane
2. control, data plane separation
1: generalized“ flow-based” forwarding (e.g., OpenFlow)
Network Layer: Control Plane
Computer Networking and Applications
Generalized Forwarding and SDN
Each router contains a flow table that is computed and distributed by a logically centralized routing controller
logically-centralized routing controller
control plane data plane
local flow table
values in arriving packet’s header
Network Layer: Data Plane 4-9
Computer Networking and Applications
Generalized Forwarding and SDN
Headers (across protocols) [source/destination/port] counters (how many packts) e.g UDP packets Actions
logically-centralized routing controller
control plane data plane
local flow table
values in arriving packet’s header
Computer Networking and Applications
OpenFlow Protocol: Flow Table Entries
Packet + byte counters
1. Forward packet to port(s)
2. Encapsulate and forward to controller 3. Drop packet
4. Send to normal processing pipeline
5. Modify Fields
Switch Port
Link layer Network layer
Transport layer
Computer Networking and Applications
OpenFlow Protocol: Flow Table Entries
• Example of a Flow Table based on the OpenFlow protocol.
• OpenFlow protocol operates between SDN controller and the SDN-controlled device implementing the OpenFlow
Computer Networking and Applications
Destination-based forwarding:
Switch MAC Port src
* ** * * * 51.6.0.8* * * port6
IP datagrams destined to IP address 51.6.0.8
should be forwarded to router output port 6
Switch MAC Port src
* * * * * * * * * 22 drop
do not forward (block) all datagrams destined toTCP port 22
Switch MAC Port src
* * * * * 128.119.1.1* * * *
do not forward (block) all datagrams sent by host 128.119.1.1
程序代写 CS代考 加微信: powcoder QQ: 1823890830 Email: powcoder@163.com