All Cisco-Network Study Notes: 12/30/08

H.323 Gatekeeper Fundamentals 462 3

H.323 Gatekeeper Fundamentals

This area reviews the functions and roles of gatekeepers and agenda gatekeepers.

Also, this area discusses in abyss the Registration, Admission, and Status (RAS) signaling

sequencing amid gateways and gatekeepers and discusses the use of the

Gatekeeper Transaction Message Protocol (GKTMP).

Configuring H.323 Gatekeepers

Gatekeepers are a above allotment of average to ample H.323 VoIP arrangement solutions. When

used, these apparatus acquiesce for dial-plan scalability and abate the charge to manage

global punch affairs locally. In this chapter, you will apprentice the functions of a attendant and

directory gatekeeper. Additionally, you will apprentice how to configure gatekeepers to interoperate

with gateways and how to accommodate attendant back-up in average to large

VoIP networks.

Verifying COR

You can use the appearance dial-peer cor command to affectation corlists and members, as demonstrated

in Example 7-40.

Example 7-40 appearance dial-peer cor Command

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Router#show dial-peer cor

Class of Restriction

COR account <911call>

member: 911

COR account

member: local

COR account

member: ld

COR account

member: intl

Summary

The capital capacity covered in this affiliate are the following:

■ Chiffre abetment is the assignment of abacus or adding digits from the aboriginal dialed

number to board user dialing habits or aperture needs.

■ Chiffre stripping strips any outbound digits that absolutely bout the destination pattern

of a accurate punch peer.

■ Chiffre forwarding specifies the cardinal of digits that charge be forwarded to a telephony

interface.

■ Chiffre prefixing adds digits to the advanced of the punch cord afore it is forwarded to a

telephony interface.

■ Cardinal amplification is activated globally to all calls, not aloof to calls analogous a single

designated punch peer.

■ By default, back a absolute router matches a punch cord to an outbound POTS

dial peer, the router strips off the left-justified digits that absolutely bout the destination

pattern.

■ You can use the clid command to adapt addition ID information.

■ You can use articulation adaptation profiles to alter the Cisco Unified CME dialplanpattern

command.

■ Configuring chiffre abetment ability crave the use of basal commands as able-bodied as

translation rules and profiles.

■ The alarm acquisition argumentation on Cisco IOS routers application the H.323 agreement relies on the

dial associate construct.

■ Routers charge bout the actual entering and outbound punch aeon to successfully

complete a call.

■ Punch aeon in a coursing accumulation are called according to belief such as longest match,

explicit preference, or accidental selection.

■ Best practices accommodate a absence POTS punch associate and bombastic Cisco UCM.

■ Back alien sites are involved, altered aisle alternative strategies are required,

including site-code dialing, toll-bypass, and TEHO.

■ Site-code dialing uses the abstraction of prefixing a armpit cipher in advanced of the actual

extension and can be accumulated with toll-bypass to avenue calls over a WAN link

instead of a PSTN connection.

■ TEHO extends the abstraction of toll-bypass by acquisition calls over a WAN to the closest

PSTN blemish to abstain cher long-distance and all-embracing buzz charges.

■ Site-code agreement requires that anniversary armpit be assigned a different armpit code.

■ TEHO agreement requires that all calls be baffled over the WAN unless the WAN

is down.

■ Calling privileges are acclimated aural a punch plan to ascertain the destination a user is

allowed to call.

■ Calling privileges are implemented on Cisco IOS gateways application the Class of

Restriction (COR) feature.

■ For Cisco Unified CME, a corlist is anon assigned to an adapted ephone. To

assign a corlist in SRST mode, a corlist is akin to a ambit of agenda numbers in

Communications Manager fallback agreement mode.

■ Configuring COR includes configuring called CORs and corlists, and assigning

corlists to punch peers, ephones, or SRST.

Configuring COR for SRST

The archetype illustrated in Figure 7-36 and Archetype 7-39 shows how to configure COR

for SRST.

Chapter 7: Configuring Advanced Punch Plans 433

V V

WAN

Extensions:

2000 - 2100

R1 R2 Unified

Communications

Manager

Figure 7-36 COR SRST Scenario Topology

Example 7-39 SRST COR Configuration

R1(config)#call-manager-fallback

R2(config-cm-fallback)#cor admission INTL 1 2000 – 2100

To configure COR for SRST, use the cor command in SRST agreement mode.

You can accept up to 20 corlists for anniversary admission and approachable call. A absence COR is

assigned to agenda numbers that do not bout any corlist numbers or cardinal ranges.

An assigned COR is invoked for the punch aeon and created for anniversary agenda number

automatically during Communications Manager fallback registration.

When allotment an admission or approachable corlist to SRST ephones, corlists can be

assigned to a specific agenda cardinal ambit (as the afterward syntax illustrates) or a

default corlist can be applied.

Router(config)#call-manager-fallback

Router(config-cm-fallback)#cor admission intl 1 2000 - 2100

The syntax of the cor command issued in call-manager-fallback agreement approach is

cor {incoming | outgoing} cor-list-name [cor-list-number starting-number -

ending-number | default]

The afterward is an account of the syntax:

■ incoming: corlist to be acclimated by admission punch peers.

■ outgoing: corlist to be acclimated by approachable punch peers.

■ cor-list-name: corlist name.

■ cor-list-number: corlist identifier. The best cardinal of corlists that can be created

is 20, absolute admission or approachable punch peers. The aboriginal six corlists are

applied to a ambit of agenda numbers. The agenda numbers that do not accept a

COR agreement are assigned to the absence corlist, provided a absence corlist has

been defined.

■ starting-number - ending-number: Agenda cardinal range, such as 2000–2025.

■ default: Instructs the router to use an absolute absence corlist.

Configuring COR for Cisco Unified Communications Manager

Express

In the afterward example, you are appropriate to configure COR for Cisco Unified CME

according to the afterward arrangement requirements.

For this example, three calling advantage classes are required:

■ Local: This chic should acquiesce emergency and bounded calls.

■ Continued Distance: This chic should acquiesce emergency, local, and continued ambit calls.

■ International: This chic should acquiesce emergency, local, continued distance, and international

calls.

Note No accepted allotment conventions abide for the advantage classes. Ensure that you

choose a anecdotic name.

You can use the afterward accomplish to configure COR for Cisco Unified CME:

Step 1. Ascertain the four alone “tags” (CORs) to be acclimated as corlist associates with

the command dial-peer cor custom.

Step 2. Ascertain the corlists that will be assigned “outgoing” to the PSTN punch peers

with the command dial-peer cor account corlist-name.

Step 3. Ascertain the corlists that will be assigned “incoming” from the bounded punch peers

with the command dial-peer cor account corlist-name.

Step 4. Associate corlists with absolute VoIP or POTS PSTN dial-peers by application the

command corlist {incoming | outgoing} corlist-name aural the dial-peer

configuration.

Step 5. Accredit the corlists for user privileges to the agnate ephone-dns.

The cartography apparent in Figure 7-35 will be acclimated throughout the agreement accomplish in

this scenario. Notice that the Chicago armpit is handled by a Cisco Unified CME router.

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PSTN

Chicago

+1 312 555XXXX

CUCME

Router

911

+1 ...

+49...

International – Emergency, Local, Continued Distance, International

Long Ambit – Emergency, Local, Continued Distance

Local – Emergency, Local

Required Calling Privileges

CUCME = Cisco Unified Communications Manager Express

0/0/0

1003 1004 Phone1-1

1001

International

Phone1-2

1002

Local Only

Figure 7-35 COR Cisco UCME Book Topology

Step 1: Ascertain COR Labels

The aboriginal footfall is to ascertain the alone CORs.

Four COR labels will be defined:

■ 911: Allows calls to emergency 911

■ Local: Allows bounded calls only

■ LD: Allows continued ambit calls

■ INTL: Allows all-embracing calls

You can use the afterward action to configure these four CORs.

Step 1. Use the dial-peer cor custom command to access COR agreement mode.

Router(config)#dial-peer cor custom

Step 2. Use the name command in COR agreement approach to actualize the named

CORs.

Router(config-dp-cor)#name 911

Router(config-dp-cor)#name local

Router(config-dp-cor)#name ld

Router(config-dp-cor)#name intl

Step 2: Configure Outbound Corlists

After you ascertain the CORs, you can configure the admission and approachable corlists.

Four approachable corlists will be defined:

■ 911call: Allows calls to emergency 911

■ Localcall: Allows bounded calls only

■ Ldcall: Allows continued ambit calls

■ Intlcall: Allows all-embracing calls

The afterward agreement defines the corlists acclimated for the outbound PSTN punch peers.

Note that anniversary corlist contains a distinct COR member.

Step 1. Ascertain a corlist name for 911 calls.

Router(config)#dial-peer cor account 911call

Step 2. Add associates to dial-peer corlists. The affiliate needs to advertence a previously

configured COR tag.

Router(config-dp-corlist)#member 911

Chapter 7: Configuring Advanced Punch Plans 429

Step 3. Repeat Accomplish 1 and 2 for the added approachable corlists.

Router(config)#dial-peer cor account localcall

Router(config-dp-corlist)#member local

Router(config)#dial-peer cor account ldcall

Router(config-dp-corlist)#member ld

Router(config)#dial-peer cor account intlcall

Router(config-dp-corlist)#member intl

Step 3: Configure Entering Corlists

After the agreement of the outbound punch aeon is complete, you can configure the

inbound punch peer. The admission corlists will after be assigned to the ephones and

inbound punch aeon acclimated for absorbed phones.

Four admission corlists will be defined:

■ 911: Allows 911 calls only

Member is 911.

■ local: Allows 911 and bounded calls only

Members are 911 and local.

■ ld: Allows 911, local, and continued ambit calls

Members are 911, local, and ld.

■ intl: Allows 911, local, continued distance, and all-embracing calls

Members are 911, local, ld, and intl.

The afterward accomplish ascertain the four entering corlists:

Step 1. The afterward agreement creates a corlist that corresponds to the calling

privilege acceptance alone emergency calls:

Router(config)#dial-peer cor account 911

Router(config-dp-corlist)#member 911

Step 2. The afterward agreement creates a corlist that corresponds to the calling

privilege acceptance alone emergency and bounded calls:

Router(config)#dial-peer cor account local

Router(config-dp-corlist)#member 911

Router(config-dp-corlist)#member local

Step 3. The afterward agreement creates a corlist that corresponds to the calling

privilege acceptance emergency, local, and continued ambit calls:

Router(config)#dial-peer cor account ld

Router(config-dp-corlist)#member 911

Router(config-dp-corlist)#member local

Router(config-dp-corlist)#member ld

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Step 4. The afterward agreement defines the corlist that corresponds to the calling

privilege acceptance emergency, local, continued distance, and all-embracing calls:

Router(config)#dial-peer cor account intl

Router(config-dp-corlist)#member 911

Router(config-dp-corlist)#member local

Router(config-dp-corlist)#member ld

Router(config-dp-corlist)#member intl

Step 4: Accredit Corlists to PSTN Punch Peers

You can again ascertain the agnate outbound punch aeon application the PSTN corlists.

Note that anniversary of the punch aeon is configured with the agnate approachable corlist:

■ Dial-peer 911 has the approachable 911call corlist.

■ Dial-peer 9911 has the approachable 911call corlist.

■ Dial-peer 9 has the approachable localcall corlist.

■ Dial-peer 91 has the approachable ldcall corlist.

■ Dial-peer 9011 has the approachable intlcall corlist.

The afterward agreement shows the complete dial-peer configuration, including correct

destination patterns, chiffre prefixing, and corlist configuration:

Step 1. Access dial-peer agreement mode.

Router(config)#dial-peer articulation 911 pots

Router(config-dial-peer)#destination-pattern 911

Router(config-dial-peer)#forward-digits all

Step 2. Specify the corlist to be acclimated back a defined punch associate acts as the incoming

or approachable punch peer. The corlist name needs to advertence a ahead configured

corlist.

Router(config-dial-peer)#corlist approachable 911call