Module 8: Concepts of a Network Load Balancing Cluster

1. Module 8: Concepts of a Network Load Balancing Cluster

2. Overview • Network Load Balancing Concepts • Application and Service Environment • Network Load Balancing Functionality • Network Load Balancing Architecture

3. Network Load Balancing Concepts • Comparing Network Load Balancing Solutions • Network Load Balancing

4. 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 Comparing Network Load Balancing Solutions

5. Round Robin DNS Static group 3 IP: 10.10.10.12 IP: 10.10.10.11 1 IP: 10.10.10.10 10.10.10.1210.10.20.11 10.10.20.10 DNS Server 2 MyRRDNSWeb   IN  A  10.10.10.12MyRRDNSWeb   IN  A  10.10.10.11 MyRRDNSWeb   IN  A  10.10.10.10 MyNLBWeb IN A 10.10.20.10 4 Cluster with up to 32 hosts 10.10.20.10 5 6 IP: 10.10.20.10 Network Load Balancing

6. Affinity sets all client connections to a single host Port Rules define which ports the cluster will service IIS Web site image Client TCP Session (Get) IIS Web site image Next client TCP Session (HTTPS) Virtual IP: 10.10.10.10 Web server TCP(80) HTTPS TCP(443) Application and Service Environment

7. 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

8. 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

9. Even Balance 1/3 Manual Balance 60% 1/3 10% 1/3 30% Load to virtual IP distributed evenly across hosts Load to virtual IP distributed based on manual configuration 2 3 1 Priority Based All load to virtual IP distributed to highest priority host Balancing Client Connections

10. Even balance without affinity • Initial client request distributed according to Network Load Balancing configuration • Subsequent client requests distributed according to Network Load Balancing configuration 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 Supporting Multiple Client Connections

11. 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 • Load Balance ½ each • Server B Joins • Convergence • Load Balance 1/3 each C B A Virtual IP: 10.10.10.10 Cluster Convergence

12. Even balance • Load balance 1/3 each • Server B Fails • Convergence • Load Balance ½ each C B A N-1 Failover Virtual IP: 10.10.10.10 Priority • Load All on Host 1 • Server 1 Fails • Convergence • Load All on Server 2 3 2 1 Virtual IP: 10.10.10.10 Network Load Balancing for High Availability

13. Network Load Balancing Cluster CPUs Memory NIC Disk Scale up Add more resources to a server Virtual IP: 10.10.10.10 Scale out Add more servers to the cluster Network Load Balancing for Scalability

14. 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 10.10.10.1010.10.20.10 DNS Server Virtual IP: 10.10.20.10 2 DNS rotates list for each query which statically load balances incoming requests MybigWeb   IN  A  10.10.10.10MybigWeb   IN  A  10.10.20.10 Cluster 2 with upto 32 hosts 4 10.10.20.10 10.10.10.10 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 Scaling Network Load Balancing Clusters

15. 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

16. Cluster Host Server Application Wlbs.exe Windows 2000 Kernel TCP/IP Network Load Balancing Driver Network AdapterDriver Network AdapterDriver Cluster Network Adapter Cluster Network Adapter LAN Network Load Balancing Driver Architecture

17. Cluster with 3 hosts Outbound traffic andInbound 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 Network Load Balancing Topology

18. 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 Selecting an IP Transmission Mode

19. 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 Network Load Balancing Addressing

20. Port Rules • Port Rules • Filtering Modes • Load Weighting • Priority

21. Affinity Load balancinggranularity 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 Session support, SSL and multi-connection protocols (ex: FTP, PPTP, etc.) Class C All connections originating from the same Class C address space Source IP address with Class C mask applied to it Property handling sessions for users residing behind scaling proxy arrays Affinity

22. Lab A: Planning an Installation

23. Review • Network Load Balancing Concepts • Application and Service Environment • Network Load Balancing Functionality • Network Load Balancing Architecture

24. Network Load Balancing Driver Architecture TCP/IP Holds Port rules for all inbound traffic NLB Driver Network AdapterDriver Assigns Common Virtual IP and MAC address Virtual IP: 10.10.10.10 MAC: 02-BF-10-10-10-10 Cluster Network Adapter Adapter can be Ethernet, Gigabit Ethernet or FDDI All Virtual IP traffic will be filtered by NLB rules