Partitions and Calling Search Spaces

A partition is a group of dialable patterns with similar accessibility. Any dialable pattern can be assigned to a partition. All phone numbers are in the null partition by default, and all devices have access to the null partition. As soon as a phone number is assigned to a different partition, the devices in the network will not be able to access that phone number without the configuration of a calling search space (CSS).

A CSS defines which partitions are accessible to a particular device. A device can call only those call-routing table entries located in partitions that are part of the CSS assigned to the device.

Partitions are assigned to call-routing targets. Any entry of the call-routing table, including voice-mail ports, directory numbers (DN), route patterns, translation patterns, meet-me conference numbers, and so on can be assigned to a partition.

CSSs are assigned to devices, which are the source of a call-routing request (phones, phone lines, gateways, trunks, voice-mail ports, and computer telephony integration [CTI] ports). Calls that come into the network from a gateway or trunk inherit the CSS assigned to the gateway or trunk.

By default, all entities that can be configured with a partition are in partition <None> (null partition), all entities that can be configured with a CSS are assigned with CSS <None> (null CSS).

Members of partition <None> are always accessible by sources of a call-routing request, regardless of the CSS applied to the calling party. Entities that do not have a CSS assigned can only access numbers that are in partition <None>. Partition <None> is commonly referred to as the null partition.

In Figure 13-1, various partitions and CSSs have been created. An easier way of understanding partitions and CSSs is to use an analogy of locks and key rings. If each house on a block has a different lock (partition), your key ring (CSS) would have to include many keys (to unlock different doors).

In Figure 13-1, DN 1 of Phone 1 has been configured in the lobby partition, and DN 1 of Phone 2 is in the employee partition, while Phone 3 and Phone 5 are both in the manager partition. Phone 4 has not been assigned to a partition. Following the analogy with locks and keys, there are three different types of locks (lobby, employee, and manager). Phone 4 does not have a lock. Phone 4 is therefore in the null partition, and everyone has access to call Phone 4.

When approaching CSSs from the perspective of key rings, Phone 1 has a key ring with the lobby and employee key on it. Phone 2 has a key ring with keys for the lobby, employee, and manager key ring. Phone 3 has a key ring with the lobby, employee, manager, and executive keys. The executive key is not seen in the example, but it will be used in the system for executive management. The key ring of Phone 4 contains only the lobby key. Phone 5 does not have any keys, which restricts Phone 5 to call only other DNs in the null partition.

As a result of this implementation of locks and keys, the following effective permissions apply:

■ Phone 1: Like all other phones, this phone has access to all devices that do not have a lock applied (Phone 4 in this example). Phone 1 can access DN 1 on Phone 2 and Phone 4. Devices cannot access DNs in the same partition unless their CSS gives explicit permission to that partition.

■ Phone 2: Phone 2 can access Phone 1, Phone 3, Phone 4, and Phone 5.

■ Phone 3: Phone 3 can access Phone 1, Phone 2, Phone 4, and Phone 5.

■ Phone 4: Phone 4 can access Phone 1 only, because the CSS has access only to the lobby partition.

■ Phone 5: Like all other phones, this phone has access to all devices that do not have a lock applied (Phone 4 in this example). Phone 5 cannot unlock any locks because it does not have any keys. That means that Phone 4 can access only Phone 1.

Figure 13-1 Calling Privileges: Partitions and Calling Search Spaces

Partitions:

Phones

CSSs:

Lobby_PT

Lobby_PT

Phone 1

Phone 1

Lobby_PT Employee_PT

Employee_PT

Employee_PT

Phone 2

Phone 2

Lobby_PT

Employee_PT

Manager_PT

Manager_PT

Manager_PT

Phone 3

Phone 3

Lobby_PT Employee_PT Manager_PT Executive_PT

No Partition Assigned

No Partition Assigned

Phone 4

Phone 4

Lobby_PT

Manager_PT

Phone 5

No CSS Assigned

Figure 13-2 illustrates a phone with a CSS that contains two partitions: Chicago and San Jose. A third partition, Atlanta, exists in the system but is not included in the CSS of the phone. Phone DNs are assigned to partitions as follows:

■ DN 3001 (Phone 2-1) is assigned to partition Chicago.

■ DN 2001 (Phone 1-1) is assigned to partition San Jose.

■ DN 4001 (Phone 3-1) is assigned to partition Atlanta.

The user at the phone dials 3001, which is the DN of Phone 2-1. CUCM performs digit analysis against the dialed digits of 3001. The call-routing lookup will search only through the partitions configured in the CSS of the calling phone (Chicago and San Jose). CUCM finds a match in partition Chicago, because the DN of 3001 of Phone 2-1 is assigned to this partition. Because no other matches exist, routing is complete, and Phone 2-1 rings.

Figure 13-2 Partition and CSS Example

Figure 13-2 Partition and CSS Example

Css Partition
g3

A CSS is an ordered list of partitions with the highest-priority partitions listed first.

Multiple identical entities can exist in the call-routing table, but they have to be in different partitions. It is advisable to route emergency calls through a local gateway in multisite centralized call-processing deployments. If 911 is the emergency number, there will be many iterations of the 911 route pattern in the system, but they must each be in a separate partition. Local call routing in a centralized call-processing approach will result in the creation of site-specific partitions and CSSs to guarantee that local PSTN resources are used.

Figure 13-3 Multiple Best Matches Example

Phone CSS contains two partitions.

User dials 3001.

User dials 3001.

CSS

Partition Chicago

y 3001

Phone 2-1

VA

Partition San Jose

2-J

^ 3001

Phone 1-1

Phone 2-1 and

^ -

Phone 1-1 match equally well. Phone 2-1 is used because its partition is listed first in calling phone's CSS.

Partition Atlanta

Phone 1-1 match equally well. Phone 2-1 is used because its partition is listed first in calling phone's CSS.

Partition Atlanta

3001

Phone 3-1

Phone 3-1

Phone 3-1 DN

3001 lies in partition Atlanta. Not included in routing decision.

Phone 2-1 DN 3001 lies in partition Chicago.

Phone 1-1 DN 3001 lies in partition San Jose.

Phone 3-1 DN

3001 lies in partition Atlanta. Not included in routing decision.

Figure 13-3 displays a CSS scenario in which the same dialed pattern matches multiple partitions. The CSS processing is based on the following order:

1. Best match is searched.

2. If multiple equally qualified matches exist (no single best match), the call routes through the partition in the CSS that is highest in the list. Many sources of call-routing requests (trunks, gateways, and translation patterns) have only one CSS. On IP phones, a different CSS can be applied per line and at the device level. If a CSS is specified only at the device level, each DN inherits the CSS of the device.

If CSSs are configured at both device and line level, the line from which the call is placed is considered first in the call-processing logic. CUCM concatenates the two CSSs and processes them in a top-down manner with the line CSS at the top of the list, as shown in Figure 13-4.

Figure 13-4 Device and Line CSS Example

Figure 13-4 Device and Line CSS Example

Line

Line

Device

Device

Line CSS

Partition L1

Partition L2

Partition L3

Device CSS

Partition D1

Partition D2

Partition D3

Resulting CSS

Partition L1

Partition L2

Partition L3

Partition D1

Partition D2

Partition D3

NOTE On CTI ports, the line and device CSS are processed in reverse order; the partitions of the device CSS are processed before the partitions of the line CSS.

In Figure 13-5, the line CSS of the calling party includes partitions San Jose and Chicago. The device CSS of the calling phone includes partition Atlanta.

Figure 13-5 CSS Partition Order Example

Line CSS

Partition San Jose

300X

Route Pattern

Partition Chicago

3001

Phone 2-1

Device CSS

Partition Atlanta

3001

Phone 3-1

Route pattern 300X is in the San Jose partition, with DN 3001 assigned to both Phone 2-1 in the Chicago partition and Phone 3-1 in the Atlanta partition.

When the phone dials 3001, the following will happen:

CUCM interprets the dialed digits and searches for the closest match. The two DN entries in the call-routing table are more specific than the route pattern of 300X. Phone 2-1 is chosen because its partition is listed first in the concatenated CSS.

Figure 13-5 illustrates the line CSS having higher priority than the device CSS. If the line CSS and device CSS were reversed, the call would be sent to Phone 3-1. Notice that the CSS subsequently performs closest-match routing against all partitions in the CSS at the same time. If the CSS had been strictly processed on the San Jose partition before considering the Chicago or Atlanta partitions, 300X would have been the match. Instead, CUCM was aware of the closest match of 3001 in the other partitions. The partition order is used as a tiebreaker if there are multiple closest matches.

NOTE It is a common misunderstanding that the first matching pattern (regardless of the quality of the match) that is found when searching through the partitions in the order specified in the CSS is used for call routing. If this were true, subsequent partitions of the CSS would only be looked at, if no match (of any kind) were found in the earlier partitions. This is not the case. All partitions are immediately considered for the bestmatch logic, and only if multiple best matches exist does the partition order become relevant.

Figure 13-6 is using partitions and CSS to implement four different classes of service:

■ Internal: Allows internal calls only

■ Local: Allows internal and local PSTN calls

■ Long Distance: Allows internal, local PSTN, and long-distance PSTN calls

■ International: Allows internal, local PSTN, long distance, and international PSTN calls The following partitions are applied as described:

■ Phones: This partition is applied to all phone lines.

■ Local-PSTN: This partition is applied to route pattern 9.[2-9]XXXXXX

■ LD-PSTN: This partition is applied to route pattern 9.1[2-9]XX[2-9]XX XXXX

■ Intl-PSTN: This partition is applied to route pattern 9.011! and 9.011!#.

The following CSSs are configured, each implementing the corresponding service class:

■ CSS-Internal: Containing partition Phones

■ CSS-Local: Containing partitions Phones and Local-PSTN

■ CSS-LD: Containing partitions Phones, Local-PSTN, and LD-PSTN

■ CSS-International: Containing partitions Phones, Local PSTN, LD-PSTN, and Intl-PSTN

Figure 13-6 CSS Example

Figure 13-6 CSS Example

Cucm Partition And Css

NOTE CSSs take on an inverted logical approach when assigned to devices such as Session Initiation Protocol (SIP) trunks, intercluster trunks, and gateways. Calls that are routed through a trunk or gateway take on the CSS applied at the device. In a multicluster distributed call-processing environment, it is not advised to allow emergency call routing across trunk links. Most organizations locally route emergency calls to the local public safety answering point (PSAP). It is common practice to restrict emergency call routing in the CSS applied to trunks.

Configuration of partitions and CSSs includes the following steps:

Step 1 Create partitions.

Step 2 Assign partitions to the DN, route-translation patterns, CTI ports, voice-mail ports, meet-me conference bridge numbers, call-park ranges, and any other number in the system.

Step 3 Create CSSs.

Step 4 Add partitions in the desired order into each newly created CSS.

Step 5 Assign CSSs to entities that can request lookups to the call-routing table to route a call; examples for such entities are phones and phone lines, trunks, gateways, and translation patterns.

NOTE A translation pattern is a dialable pattern in the call-routing table. When a translation pattern is matched, it invokes a new call-routing request for the translated pattern. Which partition the translation pattern is in limits the devices that can access the translation pattern. The CSS of the translation pattern specifies the entries of the callrouting table that the translation pattern is allowed to see for the new call-routing request when it is trying to find the translated pattern in the call-routing table.

To add partitions in CUCM Administration, navigate to Call Routing > Class of Control > Partition and click the Add New button. Figure 13-7 shows the Partition Configuration page in CUCM. You can add up to 75 partitions in one insertion of partitions with a character limitation of 1475 characters. If more than 75 partitions are required, you may perform multiple insertions.

Partition names should not be lengthy because the CSS has a maximum length restriction of 1024 characters. A CSS is a string of partition names. The 1024-character limit includes separator characters between each partition name. (For example, the string "partition_1:partition_2:partition_3" contains 35 characters.) The maximum number of partitions in a CSS varies, depending on the length of the partition names and number of partitions. If individual CSSs are used on both the device and line level, the maximum character limit for the individual CSS is 512 (half the combined CSS clause limit of 1024 characters).

Figures 13-8 and 13-9 show the application of partitions, respectively, to a DN and route pattern.

Figure 13-7 Partition Configuration

Partition Configuration

-Partition Information-

To enter multiple partitions, use one line for each partition entry. You can enter up to 75 partitions; the names and descriptions can have up to a total of 1475 characters. The partition name cannot exceed 50 characters. Use a comma (7) to separate the partition name and description on each line. If a description is not entered, Cisco Unified Communications Manager uses the partition name as the description. For example: << partitionName » , << description >> Cisco Partition, Cisco employee partition DallasPartition

Name

Intern a l_PT, Internal Directory Numbers Local_PT, Local PSTN Calls LD_PT, Long Distance PSTN Calls International_PT, International PSTN Calls e911_PT, E-911 Calls Service_PT, 3-digit Service Calls S]C_ICT_PT, San Jose Inter-Cluster Trunk Partition MWI_PT, Message Waiting Indicator Partition Unity_PT, Unity Voice Mail Port Partition!

Figure 13-8 Partition Application: Directory Number

Figure 13-8 Partition Application: Directory Number

Figure 13-9 Partition Application: Route Pattern

Figure 13-10 shows the Calling Search Space Configuration page. This page is accessible by navigating to the following CUCM Administration menu: Call Routing > Class of Control > Calling Search Space. Click the Add New button to add a new CSS. The CSS should be given a name that is descriptive of the desired functionality. LD_Calling Search Space would be descriptive of a CSS that allows long-distance, local, emergency, and internal dialing. Click a partition in the Available Partitions section of the configuration page and use the down arrow to move the partition to the Selected Partitions section. You can use the up and down arrows to the right of the Selected Partitions section to move the priority of the selected partition. The top of the list is the highest priority. The emergency partition should normally be at the top of the list.

Figure 13-11 displays the phone configuration page with a CSS applied. CSSs can be assigned to phones, phone lines, gateways, trunks, voice-mail pilots, voice-mail ports, CTI route points, CTI ports, translation patterns, and any other source of a call-routing request.

Figure 13-10 CSS Configuration

Add or remove highlighted partition to or from CSS.

Figure 13-10 CSS Configuration

Add or remove highlighted partition to or from CSS.

Change order of partitions in CSS by moving highlighted partition up or down.

Figure 13-11 CSS Configuration

+7 -4

Responses

  • Robert Stanley
    Which comes first call search space in user or phone?
    2 months ago

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