6. Wanted to solve:
Privacy
Intended human errors
Solved these too:
Unintended human errors
Speed of connections
Lowering operational costs
of running a local exchange
12. A basic example of SDN
Contoller
Control Control Control
Data Data
13. Categories of SDN
Definition Example
Cloud Service
Providers
(CSP/CAP)
• Distributed control plane • Midokura
IaaS • VMWare/Nicira
• Software solution for IaaS Cloud
Cloud use • Nuage
Enterprises
SDN
• Centralized control plane • Juniper Qfabric
Fabric • Hardware solution for DC use • NEC Programmable Flow
• Big Switch
• Hybrid control plane (CP) • Google
Carrier/ • Distributed CP with BGP
WAN • Centralized CP using
OpenFlow
13
14. Iaas Cloud Networking Requirements
• Multi-tenancy • ACLs
• L2 isolation • Stateful (L4) Firewall
Security Groups
• L3 routing isolation
VPC • VPN
Like VRF (virtual IPSec
routing and forwarding) • BGP gateway
• Scalable control • REST API
plane • Integration with CMS
ARP, DHCP, ICMP OpenStack
• NAT (Floating IP) CloudStack, etc.
15. Iaas Cloud Networking Requirements
Typical Network Topology
uplink
- Creat e one provider rout er upon deployment - Link to uplink
- Creat e a rout er f or a t enant - BGP multi-homing
- M ap a bridge f or a quant um net work - Global NAT/route settings,
e.g. for floating ip
Provider Virtual
Router (L3)
- Tenant router for
FW, LB, DHCP and NAT
Tenant/Project A Tenant/Project B
Tenant B
Tenant A
Virtual Router
Virtual Router
Network A1 Network A2 Network B1
TenantB office
Virtual L2 Virtual L2 Virtual L2
Switch A1 Switch A2 Switch B1 Tenant B
VPN Router
VM1 VM3 VM5 VM2 VM4 VM6
Office
Network
16. Candidate models
• Traditional network
• Centrally controlled OpenFlow based hop-
by-hop switching fabric
• Edge to edge overlays
17. Traditional Network
• Ethernet VLANs for L2 isolation
4096 limit
VLANs will have large spanning trees terminating on many hosts
High churn in switch control planes doing MAC learning non-stop
Need MLAG for L2 multi-path
Vendor specific
• VRFs for L3 isolation
Not scalable to cloud scale
Expensive hardware
Not fault tolerant
18. OpenFlow Fabric
• State in switches
Proportional to virtual network state
Need to update all switches in path when provisioning
Not scalable, not fast enough to update, no atomicity of
updates
• Not good for IaaS cloud virtual networking
19. Edge to Edge IP Overlays
• Isolation not using VLANs
IP encapsulation
• Decouple from physical network
• Provisioning VM doesn’t change underlay state
• Underlay delivers to destination host IP
Forwarding equivalence class (FEC)
• Use scalable IGP (iBGP, OSPF) to build multi-path
underlay
• Inspired by VL2 from MSR
20. Market trends supporting overlay solutions
• Packet processing on x86 CPUs (at edge)
– Intel DPDK facilitates packet processing
– Number of cores in servers increasing fast
• Clos Networks (for underlay)
– Spine and Leaf architecture with IP
– Economical and high E-W bandwidth
• Merchant silicon (cheap IP switches)
– Broadcom, Intel (Fulcrum Micro), Marvell
– ODMs (Quanta, Accton) starting to sell directly
– Switches are becoming just like Linux servers
• Optical intra-DC Networks
21. Example of an overlay solution
Logical Topology
vPort Virtual
Tenant A
Switch A1
Virtual vPort
Router
vPort Provider Virtual
Virtual Switch A2
vPort
Router
Tenant B
vPort Virtual Virtual
Router Switch B1
vPort
VM
MN MN VM
BGP BGP
Multi To ISP1
Homing
Internet Private IP VM
MN Network MN VM
BGP
To ISP2 Tunnel
BGP
To ISP3
VM
MN MN VM
MN MN MN
Network State Database
Physical Topology
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22. Overlays are the right approach!
But not sufficient.
We still need a scalable control plane.
Networking is not built for a self-service cloud world
Patron saint of SDNUndertaker from Topeka, KansasRumor has it:Almon believed calls sent to “the undertaker” weren’t being routed to himThought the competition had a relative working at the switching officeMoved to Kansas City. Thought the operators were giving his customers a busy signalBecame convinced that manual switching (with a switchboard operator) should be eliminated
Example of the Strowger switchesHis work led to fully automated switching centers
Examples of control protocols:ICMPARPDHCP
Core concept in CSAbstraction lends to good design, good scaling propertiesOOP vs. FunctionalOperating Systems
3 broad categories of SDNVirtual networking for or IaaS cloudsCentral control of data center network fabricCarrier networkReplace or augment distributed signalingEdge only?