1.
High Availability<br />1<br />

2.
High Availability in OCS 2007 / 2007 R2<br />Office Communications Server (OCS) 2007 and R2<br />Registration<br />Routing<br />Presence<br />Conferencing<br />HLB required for all traffic<br />Bob’s OC<br />Bob’s Phone<br />Architecture:<br /><ul><li>One monolithic Front End Service

3.
Dependency on single shared backend database (Registration, Routing, Presence, Conferencing)</li></ul>2<br />

4.
High Availability – Communications Server “14”<br />Microsoft Communications Server “14”<br />User Services Database<br />(Presence and Conferencing)<br />Architecture:<br /><ul><li>Registrar Role (Registration and Routing). Each registrar has its own SQL Express database

5.
User Services Role (Presence and Conferencing)

6.
Registrar and User Services are collocated in the datacenter (but on different servers)

7.
All user end points register with same Front End

8.
Users are load balanced by Registrars using a Distributed Hash Algorithm

9.
Registrar can be installed in remote locations</li></ul>Registrar<br />Database<br />(Registration and <br />Routing)<br />HLB is optional for SIP traffic<br />(DNS LB is recommended)<br />HLB still required for client-server<br />HTTP Traffic<br />Bob’s OC<br />Bob’s Phone<br />3<br />

10.
Resiliency Architecture<br />4<br />Branch Office<br />Registrar<br />Data Center - EE Pool 1<br />Presence<br />Conferencing<br />SBA<br />Backup<br />Registrar<br />Pool<br />AD & DNS<br />Joe’s Primary Registrar = SBA., User Services = EE Pool1 <br />Registrar<br />(Registration<br />& Routing)<br />Data Center - EE Pool 2<br />Backup<br />Registrar<br />Pool<br />Presence<br />Conferencing<br />AD & DNS<br />Registrar<br />(Registration<br />& Routing)<br />Alice’s Primary Registrar <br />& User Services = EE Pool 2<br />Bob’s Primary Registrar <br />& User Services = EE Pool 1<br />Architecture:<br />Each user has a “Primary Registrar Pool”. Each Registrar Pool can have a “Backup Registrar Pool”<br />User’s client discovers a Registrar Pool through DNS SRV. Directed to “Primary & Backup Registrar Pool”<br />Backup Registrar heart-beats Primary Registrar. If heart-beat not received within Configurable Failover Interval (default = 120 sec for branch offices), Backup starts accepting client registrations<br />

11.
Data Center Voice Resiliency<br />5<br />

12.
Data Center Voice Resiliency (EE)Failover to Backup Data Center<br />North America Data Center<br />Europe Data Center<br />Backup<br />Registrar<br />CS “14”Edge2<br />CS “14” Pool 2<br />CS “14”Edge1<br />CS “14”Pool 1<br />Failover<br />WAN<br /><ul><li>Communications Server “14” Pool. That Communications Server “14” Pool directs client to primary and backup SIP registrar

13.
Client attempts connect to Primary Registrar Pool, if fails, connects to Backup

14.
Limited feature set available on failover

15.
Enable/Disable Automatic failover, Configurable Failover interval

16.
Automatic Failback, Configurable Failback interval (No manual failback. Workaround: Stop Front End Services on Primary Registrar pool servers)

17.
What happens if Primary Data Center cannot be restored?</li></ul>6<br />

18.
Data Center Voice Resiliency (SE)Failover to Backup Data Center<br />North America Data Center<br />Europe Data Center<br />Backup<br />Registrar<br />CS “14”Edge2<br />CS “14” SE 2<br />CS “14”Edge1<br />CS “14” SE 1<br />Failover<br />WAN<br />WAN<br /><ul><li>SE Servers operate as separate systems

19.
Client DNS SRV request discovers (one or multiple) Communications Server “14” SE. That Communications Server “14” SE sever directs client to primary and backup SIP registrar

20.
Client attempts connect to Primary Registrar, if fails, connects to Backup

21.
Limited feature set available on failover

22.
Enable/Disable Automatic failover, Configurable Failover interval

23.
Automatic Failback, Configurable Failback interval (No manual failback. Workaround: Stop Front End Services on Primary Registrar servers)

24.
If Primary Data Center cannot be restored:

25.
Restore Central management Server in backup datacenter

26.
Restore other services including Presence, Conferencing by “moving” users to other Pool</li></ul>7<br />7<br />

27.
Data Center Voice ResiliencyFailover to Backup Data Center (Discovery)<br />North America Data Center<br />Europe Data Center<br />Backup<br />Registrar<br />CS “14”Edge1<br />CS “14”Edge2<br />CS “14”Pool 2<br />CS “14” DirectorPool <br />CS “14” Pool 1<br />AD DS & DNS<br />(6)<br />(5)<br />(4)<br />(3)<br />(2)<br />(1)<br />WAN<br />Client DNS SRV request. Example: DNS SRV for _sipinternaltls._tcp.contoso.com<br />DNS SRV Response includes<br /><ul><li>CS Director Pool.contoso.com:5061 Priority=0, Weight=10

28.
CSPool2.contoso.com:5061 Priority=1 , Weight=10</li></ul>Client connects via TLS to Communications Server “14” Director Pool. Sends SIP Register. Authenticates.<br />Communications Server “14” Director Pool redirects client. SIP 301 includes Primary & Backup Registrar pool<br />If Primary Registrar Pool is available, client connects and registers with it<br />Else client connects and registers with Backup Registrar Pool (CS Pool 2)<br />8<br />

29.
Metropolitan Data Center Resiliency<br />9<br />

30.
Metropolitan Data Center ResiliencyCS “14” Pool Extended Across Two Data Centers<br />NY Data Center<br />NJ Data Center<br />Passive SQL<br />Active SQL<br />CS “14”Edge<br />FE 3-4<br />FE 1-2<br />CS “14”Edge<br />Low-Latency<br />WAN<br /><ul><li>Communications Server “14” pools operate as one logical system

31.
Split Front End pool across two datacenters (all FEs active)

32.
SQL Geo cluster for backend (Stretched Virtual Local Area Network (VLAN))

33.
Data replication is done by storage arrays (Ex: EMC SRDF, HP CLX EVA)

34.
Requires low latency WAN (15 milliseconds)

35.
In one site is down, clients are serviced by FEs in other site

36.
Nearly all features available

37.
PSTN termination may affect inbound calls

38.
Failback has to be manually initiated</li></ul>10<br />

39.
Metropolitan Data Center ResiliencyCS “14” Pool Extended Across Two Data Centers<br />NY Data Center<br />NJ Data Center<br />Passive SQL<br />Active SQL<br />CS “14”Edge<br />CS “14”Edge<br />FE 1-2<br />FE 3-4<br />Low-Latency<br />WAN<br />11<br />DNS Srv<br />DNS Server<br />Pool.contoso.com<br />