Expert Reference Series of White Papers. Cisco TelePresence Zones

Transcription

1 Expert Reference Series of White Papers Cisco TelePresence Zones COURSES

2 Cisco TelePresence Zones Brian R Mahler, CCNA, CCNP, CCNA-Voice, CCNP-Voice, Tandberg Systems Engineer Introduction There are many zones in Cisco TelePresence products; so many, in fact, that there is a lot of confusion about the different zones and their uses. This white paper should help clarify the many zones and their uses within Cisco TelePresence products. The Concept of Zones But first a little history. The concept of zones came from the well-established protocol H.323 RAS, which stands for Registration Admission and Status (RAS), and is used with H.323 Gatekeepers. Gatekeepers are used in Voice over IP (VoIP) networks to resolve phone number (E.164) to IP address, meaning if I dialed the phone number (555) , what IP address would I send it to? This phone number to IP address mapping is one of the required roles of a Gatekeeper. Another required role of the Gatekeeper is Call Admission Control (CAC). CAC monitors the number of active calls for all devices in a local zone and when the configured bandwidth is maxed, the CAC will deny all additional call requests until enough active calls drop off, and there is sufficient bandwidth available for another call. Simply put, CAC is the ability to monitor and deny calls. The two primary roles of Gatekeepers are phone number resolution and CAC. There are other rolls that gatekeepers can perform, but for the purpose of this paper, we will limit it to just those two. H.323 Gatekeepers only have two zones, Local Zones and Remote Zones. Local zones are used by Gatekeepers to indicate the CAC. With Local Zones, phone number (E.164) resolution processing is done by the local gatekeeper. Remote zones also indicate the CAC, but the phone number (E.164) resolution processing for a particular call is done by a remote device, and we would need to ask the remote device for the CAC and E.164 processing results before we could route the call. Cisco TelePresence VCS Cisco s TelePresence Video Communication Server (VCS) uses the same H.323 RAS zones concept and adds additional capabilities to better suit the user s needs. The VCS supports H.323 and all its features (local and remote zones) and adds some additional features called Subzones. These subzones perform the same functions as H.323 Local zones, but allow us to have several local zones (now called subzones) that still fall under the control of the original Local zone. By adding subzones, we have a more granular CAC and phone number resolution in the local zone. This is a new feature in H.323. Copyright 2013 Global Knowledge Training LLC. All rights reserved. 2

3 Here is a list of default subzones that come predefined on a VCS upon installation. Local Zone: This is the parent zone and all endpoints, even those that are registered to a subzone, are ultimately under this zone. Although no devices can register directly to this zone they must register to a subzone, all subzones are created under or within this parent local zone. Default Subzone: This is the default subzone. This is where all devices will register, barring any rules dictating that registration not be allowed or specifying registering to a different subzone. Traversal Subzone: This is a special zone that is used for firewall transversal, or any time network address translation (NAT) or port address translation (PAT) are used. Let s look at the two basic functions of these subzones: phone number (E.164) resolution and CAC. Phone Number Resolution Phone number (E.164) resolution is handled by registrations. By allowing a device to register to a gatekeeper, the gatekeeper is then aware of the device s phone number and its IP address, the two things required to perform the phone number resolution. Thus, I can call a phone number or an IP address, and the VCS can resolve into the IP address. Call Admission Control (CAC) CAC is done by three parameters defined within each subzone. They are called Within, In&Out, and Total. All three of these parameters have maximum limits of bandwidth allowed relative to its particular subzone. Within: Defines the maximum allowed bandwidth of all calls that stay contained within the subzone. If there are two devices registered to the same subzone, a call between those same two devices would be classified as within. In&Out: Defines the maximum allowed bandwidth of all calls that have an endpoint in this subzone and another party that resides in different zone or subzone. Total: Defines the maximum allowed bandwidth of all calls both within and in&out. Zones in Action Now let s put this all together to see how it works. Let s say we have a company and the corporate office is in San Jose CA, with a branch office in Portland OR, and another in Houston, TX. IP Addressing A feature of subzones is the ability to control what endpoints are registered to what subzones using rules. For example, let s use an IP address to dictate where a device registers. In Figure 1, /24 will register Copyright 2013 Global Knowledge Training LLC. All rights reserved. 3

4 to the San Jose Subzone, while /24 address will register to the Portland Subzone, and finally the /24 address will register to the Houston subzone. This use of IP addresses is straight forward enough, but you could also use domain names if you prefer. You can also create filters that identify what is allowed or what is denied. You have the flexibility to choose whatever works best for your situation. CAC Capabilities Next we will want to consider the CAC capabilities of the subzones. There are three parameters to work with: Within, In&Out, and Total. Within Parameter The Within parameter defines the maximum bandwidth of all calls originating and terminating within this subzone. See Figure 2 for a visual interpretation. For example; Endpoint 1 can call Endpoint 2 as long as the bandwidth stays below 3Mb/sec. Endpoint 3 can also join in the same call with Endpoint 1 and Endpoint 2 as long as all the aggregate bandwidth of all three endpoints does not exceed 3Mb/sec. So the within parameter sets the maximum bandwidth of all calls that originate and terminate within a single subzone. In&Out Parameter The In&Out parameter defines the maximum amount of bandwidth that originates inside a particular subzone and terminates in a different zone or subzone. For example, Endpoint 4 can call Endpoint 1 (see Figure 2). For this particular call, the VCS system verifies that this call does not exceed the In&Out limit set in the originating Portland Subzone, and then it would also verify that this call would not exceed the In&Out bandwidth limit of the terminating San Jose subzone as well. If this call does not exceed either subzone In&Out bandwidth limit, Copyright 2013 Global Knowledge Training LLC. All rights reserved. 4

5 then the call is allowed. So both the originating subzone and the terminating subzone In&Out parameters are checked before the call can be connected. Total Parameter The Total parameter looks at the big picture of a subzone; the total bandwidth is a maximum amount allowed of both Within and In&Out parameters combined. For example, we have a call between Endpoint 1 and Endpoint 2 with a 1 Mb/sec stream for a Within value of 1 Mb/sec., and a second call between Endpoint 5 and Endpoint 3 using another 1Mb/sec stream for an In&Out value of 1 Mb/sec as well. This translates to a Total bandwidth consumed of 2Mb/sec, which is well below the 5Mb/sec maximum set in Figure 2, above. In summary, the Total bandwidth limit in a subzone is the maximum combined sum of Within and In&Out bandwidths within a particular subzone. These parameters are the three CAC mechanisms used to limit the maximum amount of bandwidth of subzones and can be very useful to prevent oversubscribing on the LANs and WANs in our corporate networks. TelePresence Management Suite (TMS) Software The Cisco TelePresence Management Suite (TMS) is an optional piece of software that supplements the Cisco VCS products, and it is not required for operation. The added benefit of purchasing this optional component is to simplify management of the TelePresence system. The TMS then becomes the central management interface from which an administrator can add, configure, and maintain all the components used in TelePresence products. We are not here to discuss all of the features or reasons to purchase the TMS software. What we will cover is the aspect of zones and how they are used inside TMS. Don t confuse the zones used in the TMS software with the zones and subzones in the VCS. The TMS zones do not do CAC or Address resolution at all; the TMS zones are used strictly for routing calls. There are two different zones with in the TMS application that are used for routing, the ISDN Zone and the IP Zone. These zones determine the preferred route to place a call as well as an alternate or backup route. Calls can be routed across the Public Switch Telephone Network (PSTN), also known as the ISDN network, using normal telephone numbers or we can route the call across an existing IP network using IP addresses. The system administrator can select either the ISDN zone or IP zone as the preferred path, and if the preferred path is not available, the administrator can choose the other zone as the backup path. To accomplish routing across either network, our destination address needs to accommodate the addressing of the desired network, meaning phone numbers or IP addresses. By configuring an ISDN zone for a particular endpoint, the administrator is defining the ISDN number that needs to be dialed to reach that particular endpoint. For example, let s say I have an endpoint in Salt Lake City, Utah that can be reached directly by dialing the PSTN number of 1(801) , and this same endpoint has an IP address of First, I would create an ISDN zone called SLC and assign it to the endpoint and define the following ISDN information: country code = 1, area code = 801, and a phone number of Then I would create an IP zone and provide the IP address of The final step is to define the preferred zone to reach this endpoint. The preferred zone would be either the SLC ISDN zone (if I want the call to go across the ISDN network) or the IP zone (if I wanted the call to be routed over the IP network). I could also specify an alternate zone (either ISDN or IP) if the preferred path is not available. Copyright 2013 Global Knowledge Training LLC. All rights reserved. 5

6 Summary In summary, we have many zones in Cisco TelePresence products; some are used for Call Admission Control (CAC) and address resolution, like the subzones we created in the VCS products. Other zones, the ISDN and IP zones used in the TMS products, are used for an entirely different purpose, which is path selection (defining a preferred path and an alternate path for which to route a call). I know from teaching many classes that the concept of zones is confusing to many people. I hope this explanation helps clear up the confusion with zones. Learn More To learn more about how you can improve productivity, enhance efficiency, and sharpen your competitive edge, Global Knowledge suggests the following courses: Implementing Advanced TelePresence Video Solutions Part 1 v1.0 (PAITAVS1) Implementing Advanced TelePresence Video Solutions Part 2 v1.0 (PAIATVS2) Visit or call COURSES ( ) to speak with a Global Knowledge training advisor. About the Author Brian R. Mahler, CCNA, CCNP, CCNA-Voice, CCNP-Voice, Tanberg Systems Engineer, Certified Forensics Examiner plus many others. Brian has held many positions in his 30+ year career working with Computers. He has Systems Engineer, Field Engineer, Training Manager, Project Engineer, Certified Systems Instructor, for the last 15 years he has been working extensively with Cisco Voice and Video products, Developing Cisco courses, teaching Cisco classes and providing consulting services in the areas of Voice/Video over IP and Quality of Service (QoS). Currently he runs a company called NICS, LLC that offers consulting, and teaching of all Cisco classes having to do with UCM, UNITY, and UCCE. Copyright 2013 Global Knowledge Training LLC. All rights reserved. 6