Transcript 2087a_08
Module 8: Concepts of a
Network Load
Balancing Cluster
Overview
Network Load Balancing Concepts
Application and Service Environment
Network Load Balancing Functionality
Network Load Balancing Architecture
Network Load Balancing Concepts
Comparing Network Load Balancing Solutions
Network Load Balancing
Comparing Network Load Balancing Solutions
Round robin DNS
Hardware
Dispatch
NLB
Easy to Install
Yes
____
____
Yes
Hardware
Requirements
____
Yes
____
____
Single Point
of Failure
____
Yes
Yes
____
Easily
Scalable
Yes
____
Limited
Yes
High
Performance
Yes
Yes
Limited
Yes
Fault
Tolerance
No
Limited
Limited
Yes
Network Load Balancing
Round Robin DNS
Static group
3
IP: 10.10.10.12
IP: 10.10.10.11
1
10.10.10.12
10.10.20.11
10.10.20.10
IP: 10.10.10.10
DNS Server
2
MyRRDNSWeb
MyRRDNSWeb
MyRRDNSWeb
MyNLBWeb
IN A
IN A
IN A
IN A
4
10.10.10.12
10.10.10.11
10.10.10.10
10.10.20.10
Cluster with up to
32 hosts
10.10.20.10
5
6
IP: 10.10.20.10
Application and Service Environment
Affinity sets all client
connections to a single
host
Port Rules define which
ports the cluster will
service
Client TCP Session (Get)
IIS Web site image
IIS Web site image
Next client TCP Session (HTTPS)
Virtual IP: 10.10.10.10
Web server TCP(80)
HTTPS
TCP(443)
Applications and Services
Compatible Network Load Balancing Applications and
Services
Use TCP connections or UDP data streams
Support client updateable data stores
Support maintenance of client session state
Incompatible Network Load Balancing Applications and
Services
Bind to or reference computer names
Hold files exclusively and continuously open
Network Load Balancing Functionality
Balancing Client Connections
Supporting Multiple Client Connections
Cluster Convergence
Network Load Balancing for High Availability
Network Load Balancing for Scalability
Scaling Network Load Balancing Clusters
Balancing Client Connections
60%
Manual Balance
1/3
Even Balance
1/3
10%
1/3
30%
Load to virtual IP
distributed based on
manual configuration
Load to virtual IP
distributed evenly
across hosts
2
3
1
Priority Based
All load to virtual IP
distributed to
highest priority host
Supporting Multiple Client Connections
Initial client request distributed according to Network Load
Balancing configuration
Subsequent client requests distributed according to Network
Load Balancing configuration
Even balance
without affinity
Initial Client TCP session
Virtual IP: 10.10.10.10
Initial client request distributed according to Network
Load Balancing configuration
Subsequent client requests accepted by the same server
for that client IP address
Even balance
with affinity
Initial Client TCP session
Virtual IP: 10.10.10.10
Cluster Convergence
Even balance
Load balance 1/3 each
Server B Fails
Convergence
Load Balance ½ each
C
B
A
Virtual IP: 10.10.10.10
Even balance
C
B
A
Virtual IP: 10.10.10.10
Load Balance ½ each
Server B Joins
Convergence
Load Balance 1/3 each
Network Load Balancing for High Availability
Even balance
C
B
A
Load balance 1/3 each
Server B Fails
Convergence
Load Balance ½ each
N-1 Failover
Virtual IP: 10.10.10.10
Priority
3
Virtual IP: 10.10.10.10
2
1
Load All on Host 1
Server 1 Fails
Convergence
Load All on Server 2
Network Load Balancing for Scalability
CPUs
Scale up
Add more resources to a server
Disk
Memory
NIC
Virtual IP: 10.10.10.10
Scale out
Add more servers to the cluster
Network Load
Balancing Cluster
Scaling Network Load Balancing Clusters
Cluster 1 with up
to 32 hosts
•Query DNS for MybigWeb
•DNS resolves to list of IPs
•Client selects first in list
•Creates session with server
3
1
10.10.10.10
10.10.20.10
DNS Server
Virtual IP: 10.10.20.10
2
MybigWeb IN A 10.10.10.10
MybigWeb IN A 10.10.20.10
10.10.20.10
10.10.10.10
DNS rotates list for each
query which statically load
balances incoming requests
Cluster 2 with up
to 32 hosts
4
5
6
•Query DNS for MybigWeb
•DNS resolves to list of IP’s
•Client selects first in list
•Creates session with server
Virtual IP: 10.10.20.10
Network Load Balancing Architecture
Network Load Balancing Driver Architecture
Network Load Balancing Topology
Selecting an IP Transmission Mode
Network Load Balancing Addressing
Port Rules
Affinity
Network Load Balancing Driver Architecture
Cluster Host
Server Application
Wlbs.exe
Windows 2000 Kernel
TCP/IP
Network Load Balancing Driver
Network Adapter
Driver
Cluster
Network Adapter
LAN
Network Adapter
Driver
Cluster
Network Adapter
Network Load Balancing Topology
Outbound traffic and
Inbound to dedicated IP
Hub or switch
Hub or switch
Router
Inbound traffic
Virtual IP: 10.10.10.10
Single Subnet
Multicast or Unicast
Common MAC address
Driver configuration
Cluster with 3
hosts
Selecting an IP Transmission Mode
Adapters
Mode
MAC
Advantage
Disadvantage
Single
Unicast
Single
Simple
Low peer
performance
Single
Multicast
Multiple
Medium
Performance
Complex
Multiple
Unicast
Multiple
Best Balance
None
Multiple
Multicast
Multiple
Best Balance
Complex Network
Configuration
Network Load Balancing Addressing
Example
• Clients access DNS to resolve IP address
• Clients ARP to resolve IP to MAC
• All cluster hosts reply to ARP
• Client Syn to start TCP connection
• Server Asyn for selected cluster host
• Client ASyn
Cluster with 3
hosts
Hub or switch
Note:
• All client traffic arrives at all hosts for virtual IP
• Algorithm selected host replies
• Traffic to dedicated IP can be the same MAC address
Virtual IP: 10.10.10.10
Single Subnet
Multicast or Unicast
Common MAC address
Port Rules
Port Rules
Filtering Modes
Load Weighting
Priority
Affinity
Load balancing
granularity
Algorithm
hashes on
Used for
None
Individual TCP
connections
Source IP address
and port
Most applications
Single
All connections
originating from the
same source
Source IP address
Class C
All connections
originating from the
same Class C
address space
Source IP address
with Class C mask
applied to it
Affinity
Session support, SSL
and multi-connection
protocols (ex: FTP,
PPTP, etc.)
Property handling
sessions for users
residing behind
scaling proxy arrays
Lab A: Planning an Installation
Review
Network Load Balancing Concepts
Application and Service Environment
Network Load Balancing Functionality
Network Load Balancing Architecture
Network Load Balancing Driver Architecture
TCP/IP
Holds Port rules for all inbound traffic
NLB Driver
Network Adapter
Driver
Virtual IP: 10.10.10.10
MAC: 02-BF-10-10-10-10
Assigns Common Virtual IP and MAC address
Adapter can be Ethernet, Gigabit
Ethernet or FDDI
Cluster
Network Adapter
All Virtual IP traffic will
be filtered by NLB rules