Slides from the SFBay OpenStack Meetup TOPIC: Unified Underlay and Overlay SDNs for OpenStack Clouds ABSTRACT: With unified underlay and overlay SDNs, IT and operators can leverage best of both technologies to build service-rich SDNs for OpenStack clouds. At this meet up, PLUMgrid will discuss an overlay SDN architecture for service rich SDNs with service function chaining for 3rd party VNFs and demonstrate how to build that using Cisco Nexus 9K as the underlay to leverage the power and throughput of the Nexus fabric.

1. Unified Underlay and Overlay SDNs for OpenStack Clouds
Gaetano Borgione Distinguished Engineer, CTO Office
Jan 07, 2016

2. Copyright © PLUMgrid, Inc. 2011-2015
• Underlay and Overlay Networks overview
• Interaction between Underlay and Overlay Networks
• Native Underlay component integration w/t SDN framework
• VTEP Gateway use case
• VTEP integration demo
Agenda
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3. Underlay and Overlay Networks overview
…a journey across Network Architecture evolution

4. Copyright © PLUMgrid, Inc. 2011-2015
• Underlay Network (or simply "Underlay") it's what we used to call as
"the network" or "network infrastructure"
• In simple terms, it's the common underlying layer2/3+ network
carrying end-to-end data traffic between end points connected to it
• Nowadays, SDN movement tends to diminish relevancy of classic
network functions to the point where the physical network it's "just"
an underlay…
…but that's really the case ???
Underlay Network
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5. Copyright © PLUMgrid, Inc. 2011-2015
Underlay Network evolution for Data Center
…adapting to evolving needs
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• It's a network, built on top of another network
• Nodes in the overlay network can be thought of as being connected by
virtual or logical links, each of which corresponds to a path in the underlying
network
• Key characteristics for state-of-art overlay solutions:
• Multi-tenancy: traffic segregation among tenants
• Overlapping IP address space supported among tenants
• Location to Identity separation for end-station (VMs / Servers)
• Placement / Migration independent of underlay resource provisioning
• Able to scale
• Hmm… this sounds like VPNs J
Overlay Networks
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Overlay Network evolution
…adapting to evolving use cases
EoMPLS, VPLS LSM
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Overlay Network evolution on steroids
…to handle VM's compelling requirements
Network Virtualization architecture in Cloud Data CenterClassic Multi-Tenant architecture in Data Center
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Physical and Virtual Network recap
Physical Network Infrastructure
• QoS, Bandwidth & Latency
• Multicast
• Capacity
• Connectivity
Virtual Network Infrastructure
• On-Demand & Multi Tenant
• Automated & Self Service
• Virtual Domains
• Rich set of Network Functions
• Secure
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Virtual Network A Virtual Network B

10. Interaction between Underlay and Overlay networks

11. Copyright © PLUMgrid, Inc. 2011-2015
Different needs…
Cloud IT Customers Infra IT Customers
Configuration of the underlying
fabric requires orchestration and
management of the physical network
Assess Interoperability issues
among involved physical network
components in underlay and overlay
network
SLA
Visibility into Application / Service
affected by Failure or Congestion
SLA
• Quality of Service (got non-
blocking fabric ?)
• Quick Restoration of traffic paths
upon failures
Monitoring
E2E
Connectivity
Link State
Route State
Congestion
Latency
Support applications not working
well in virtualized environments
API-based networking configuration
for virtual and physical workloads
Onboard bare metal servers
not aware of overlay network
Debugging and Troubleshooting
Open Standards
P+V path
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12. Copyright © PLUMgrid, Inc. 2011-2015
• Lack of mutual awareness
• Basic integration
• Physical devices in the underlay directly terminate the Overlay
tunnels
• Overlay control plane "interact" with such devices to control /
monitor / synchronize their state
• Extended integration
• enhanced visibility and unified management between overlay
and underlay
• Solution perceived more like a "programmable fabric" than a
truly modular Overlay / Underlay architecture
…lead to different 'levels' of interaction
Cloud IT Customers
Infra IT Customers
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13. Native Underlay component integration w/t
SDN framework
VTEP Gateway Use Case

14. Copyright © PLUMgrid, Inc. 2011-2015
Hardware Gateway intro
• Hardware Gateway is a dedicated Hardware equipment with specialized support for
Overlay Networks
• Basic functionality supported by Hardware Gateway is L2 VTEP termination
• Bridged connectivity and VXLAN Encapsulation / Decapsulation operations are fully
supported in Hardware
• Typically deployed to fulfill East/West interconnectivity needs
• Packet Switching Performance are close to classic HW Switching performance
• High Port Density allows larger number of physical devices / workloads to be on-
boarded to Virtual Domain(s)
• Hardware Gateways can be “teamed” to provide Active/Active resiliency for external
connections
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15. Copyright © PLUMgrid, Inc. 2011-2015
Hardware Gateway to the rescue
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Spine(s)
Leaf(s)
Hardware
Gateway(s)
Compute Node(s)
VM VM VM VM VM
VM VM
VM
Outer MAC Header +
Outer IP Header +
Outer UDP Header +
VXLAN Header
Original Payload
Database
Server(s)
Load Balancer(s)
MLAG
SAN
Intranet
Bare Metal Server(s)

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Shared Disk
Array(s)
Database
Server(s)
SAN
Mirroring /
Replication
Network
Backup
Device(s)
DB
Network
Client
Network
Client(s)
Load
Balancer
App
VM
App
VM
App
VM
Application
Network
A Typical Use Case…

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L2 VTEP
HW Gateway
VTEP.1
VTEP.N
IP Fabric
Virtual Connector onboards
VLAN configured on
L2 VTEP HW Gateway,
Managing MAC to VTEP bindings
L3
connectivity…
App
VM
App
VM
App
VM
App
VM
Virtual Topology
Load
Balancer
VM
VM
VM
SAN
From Virtual to Physical networking

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Programming of Static MAC entries on L2 VTEP HW Gateway
IP Fabric
Virtual Domain
VM VMVM
VLAN 100
VNI 1001
vlan100
VM
2
VM
1
Director Cluster
VM
3
MAC VXLAN ID Remote VTEP
Client1 1001 <local port>
VM1 1001 VTEP1
VM3 1001 VTEP2
LB_MAC 1001 VTEP1(*)
VLAN VXLAN ID
100 1001
Client1
VTEP.2
VTEP.1
L2 GW
Agent
Virtual Topology
Internet
IP Fabric
Under the hood...

19. Time for a DEMO ?

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Underlay + Overlay
Better TOGETHER !!!
Best of Bread
Open Standards
Take-Away notes…
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