Neutron Deployment at
Scale
Igor Bolotin, Cloud Architecture
Vinay Bannai, SDN Architecture
About ebay inc
eBay Inc. enables commerce by delivering flexible and
scalable solutions that foster merchant growth.
With 145 million active buyers globally, eBay is one of the world's
largest online marketplaces, where practically anyone can buy and
sell practically anything.
With 148 million registered accounts in 193 markets and 26
currencies around the world, PayPal enables global
commerce, processing almost 8 million payments every day.
eBay Enterprise is a leading provider of commerce
technologies, omnichannel operations and marketing solutions.
It serves 1000 retailers and brands.
Outline of the Presentation
• Business case
• Cloud at eBay Inc
• Deployment Patterns
• Problem Areas
• How we addressed them
• Future Direction
• Summary
• Q&A
What our businesses need?
• Agility
− Reduce time to market
− Enable innovation
• Efficiency
− Elastic scale
− Reduce overall cost
• Multi-Tenancy
• Availability
• Security & Compliance
• Software Enabled Data Centers
Cloud at eBay Inc
Global Orchestration
Identity & Image
Management
Region/DC
Region/DC
AZ
eBay Inc
Cloud
AZ
Region/DC
AZ
Region/DC
AZ
Openstack
Controllers
Nova Cells
5
Deployment Patterns
• Private Cloud for all eBay Inc properties
• Global Orchestration with traffic and load balancing
• Identity Management
− Region level (eventually global)
• Image Management
− Region level
• Nova/Cinder/Neutron
− Availability Zones
− Active/Active servers
• Trove
• Zabbix for monitoring
• All services run behind a load balancer VIP
Deployment Patterns (contd.)
• Shared Cloud between tenants
• Different types of tenants
− eBay Production, PP production, StubHub, GSI Enterprise etc
− Dev/QA
− Sandbox environment, internal tenants (IT, VPCs)
• Production Traffic
− All bridged and no overlays
− No DHCP
• Dev/QA and some of the internal tenants
− Overlays
− DHCP
Gateway
Nodes
Physical
Racks
8
Areas With Scale Issues
• Hypervisor Scale Out
• Overlay Networks
• Bridged Networks
• Neutron Services (DHCP, Metadata, API server)
• SDN Controllers
• Network Gateway Nodes
• Upgrade
Hypervisor Scale Out
Nova
Nova
API
Nova
API
API
Neutron
Neutron
API
Neutron
API
API
Nova
Nova
Cells
Nova
Cells
Cells
Nova
Nova
Cells
Cells
Nova
Sched
Nova
Nova
Cells
Cells
Nova
Sched
DHCP
DHCP
Agent
Agent
SDN
SDN
Contrl
Contrl
10
Hypervisor Scale Out
• Several hundreds of hypervisor in a cell
• Multiple cells in a AZ
• Several thousands of hypervisors in a AZ
• Nova cells mitigate hypervisor scale
• Neutron scaling
− Majority of the hypervisors support Bridged VM’s
− Hybrid mode with both overlay and bridged VM’s
Bridged and Overlay
Tenant on
Bridged
Network
VM
VM
VM
VM
VM
VM
VM
VM
VM
L2
L3
L2
L2
Network Virtualization Layer
VM
Tenant on
Overlay
Network
Overlay Networks
• Overlay technology
− VXLAN
− STT
• Handling BUM traffic
− ARP
− Unknown unicast
− Multicast
• Logical switches and routers
• Distributed L3 routers
− Direct tunnels from hypervisor to hypervisor
• Scale out deployment of Gateway nodes
Neutron Services
• Keystone tokens
• Single threaded Quantum/Neutron server
• DHCP Servers
• Healing Instance Info Caching Interval
Keystone Token Generation and Authentication
Client
• UUID based Token
– Needs to be authenticated by
the keystone server for every
call
• PKI based Token
– Authenticated by the servers
using Keystone certs
• Token caching
– Prevents unnecessary token
creation
Nova
Server
Neutron
Server
Client
Cinder
Server
Client
Image
Server
Keystone
Server
15
Token Caching
• Applies to uuid based tokens
− 98% of tokens generated by inter-API services
− 92% are quantum/neutron related
− Average of 25 to 30 tokens/sec created by quantum/neutron alone
− RPC call overhead, bloated token table
• Fix
− Use token caching (1 hour)
− Use PKI for service tenant
− Reduces network chatter and improves performance
• Openstack bugs
− Bug id : 1191159
− Bug id : 1250580
Neutron Multi Worker
• Prior to Havana
• One api thread handling both REST calls and the RPC calls
• Broke up the api to two threads
− One handles REST API calls
− The other handles RPC calls
• Havana fixes
− DHCP renewals not handled by neutron servers, instead dhcp_release
− Multi-worker support
Heal Instance Info Cache Interval
• All nova computes regularly poll neutron server
• To get network info of the instances running on the compute
node
• Default is 10 seconds
• Hundreds of hypervisors and tens of thousands of VM’s will add
up
− Even though only one instance is checked for each interval
• We adjusted the interval to 600 seconds
DHCP Scaling
• The most common source of problems
• We employ multiple strategies
− DHCP active/standby
− Planning to support DHCP active/active
− No DHCP/Config Drive option
• Production Environment
− No DHCP
− Config drive management
− Requires “cloudinit” aware images
SDN Controllers
Nova
API
Neutron
API
SDN
Controller
OS
Ctrl
OS
Ctrl
Neutron
API
SDN
Controller
OS
Ctrl
Neutron
API
SDN
Controller
Network Gateway Nodes
• Only with overlay networks
• Scale out architecture
• Problems with high CPU utilization
• Number of flows in the gateway node
• East – West traffic also hitting VIPs
− Load Balancer running as a appliance on a hypervisor
− Using SNAT
• OVS Enhancements
− Use megaflows in openvswitch
− Multi-core version of ovs-vswitchd
OVS Improvements
Megaflows
• Prior to OVS 1.11
• Megaflow introduces wildcarding in kernel module
• Fewer misses and punts to user space
• Reduced number of flows in kernel
• Requires OVS 1.11 or greater
• Cons
− Using security groups nullifies the effects of megaflows
OVS Improvements
Multi-Core
cpu cores
vswitchd
vswitchd
User Space
Kernel Space
Kernel module
OVS < 2.0
Kernel module
OVS >= 2.0
23
Future Work
• VPC model
• Neutron Tagging Blueprint
− Network Assignment for Bridged VM’s
− Network Selection for VPC tenants
− Network Scheduling
− Additional meta data information
• Blueprint
− https://blueprints.launchpad.net/neutron/+spec/network-tagging
Network Assignment in Bridged VM’s
• There are two primary ways to plumb a VM into a network
− Pass the net-id to the nova boot
− Create a port and pass it to nova boot
• Nova schedules the instance without much knowledge about
the underlying network
• BP proposes to address this issue as one of the use cases
Network Tagging
VM
FZ1
FZ2
FZ3
FZ4
Rack 1
N1
Rack 2
N2
Rack 3
N3
Rack 4
N4
26
Summary
• Know your requirements
• Understand your size and scale
• Pick the SDN controller based on your needs
• Design with multiple failure domains
• Overlay, Bridged or Hybrid
• Monitor your cloud for performance degradation
Thank you.
Yes. We are hiring!
dl-ebay-cloud-hiring@corp.ebay.com