Configuring H.323 Gateways
Options for ambience up an H.323 aperture accommodate the following:
■ Accredit H.323 VoIP alarm casework (required)
■ Configure an interface as an H.323 aperture interface (required)
■ Configure codecs (optional)
■ Configure Dual Tone Multifrequency (DTMF) and fax broadcast (optional)
■ Acclimatize H.225 settings (optional)
Depending on the deployment scenario, you ability be configuring alone the appropriate features
or abounding of the options accessible for an H.323 articulation gateway.
H.323 Agreement Example
Figure 5-12 offers a sample cartography that needs to be configured for H.323.
Chapter 5: Examining VoIP Gateways and Aperture Control Protocols 263
UCM
Lo0:
10.10.1.1
IP Network
PSTN/Private
Network
PSTN/Private
V V Network
Figure 5-12 H.323 Agreement Archetype Topology
As a arrangement administrator, you accept been asked to arrange an H.323-based VoIP network
between two accumulated sites. Both sites are application a Cisco IOS H.323 capable
gateway for the alien connection. You should arrange the arrangement to accommodated network
requirements:
■ Use H.323 as a signaling protocol.
■ The H.323 ID of the aperture should be gw1.
■ A loopback interface is to be acclimated as the affiliation to the alien site.
■ Multiple codecs charge be accessible for agreement in this order:
■ G.711
■ G.729
■ E.164-Address Registration charge be configured, because some phones are directly
connected to the gateway.
■ H.323 timers charge to be tuned.
A four-step action can afresh be followed to configure an H.323 aperture according to
network requirements:
Step 1. Accredit H.323 VoIP casework globally.
Step 2. Configure an interface as an H.323 gateway.
Step 3. Actualize a codec articulation chic and abide with a account of codecs in adjustment of their
preference.
Step 4. Acclimatize H.225 timers.
These four accomplish are abundant as follows:
Step 1. Accredit H.323 VoIP casework globally.
Enter voice-service agreement approach and specify a voice-encapsulation
type.
Router(config)#voice account {pots | voatm | vofr | voip}
The afterward is a description of the syntax:
■ pots: Plain Old Telephone Account (POTS) articulation service
■ voatm: Articulation over ATM (VoATM) encapsulation
■ vofr: Articulation over Frame Broadcast (VoFR) encapsulation
■ voip: Articulation over IP (VoIP) encapsulation
Voice-service agreement approach is acclimated for packet telephony account commands
that affect the aperture globally.
Select H.323-call-processing submode and accredit the H.323 articulation service
configuration commands.
Router(conf-voi-serv)#h323
Activate the service.
Router(conf-voi-serv)#no shutdown
Step 2. Configure an interface as an H.323 gateway.
Enter interface agreement approach for the interface that is affiliated to the
gatekeeper.
Router(config)#interface interface
Assign an IP abode to the interface.
Router(config-if)#ip abode ip-address network-mask
Identify the interface as a VoIP aperture interface.
Router(config-if)#h323-gateway voip interface
Define the H.323 name of the gateway.
Router(config-if)#h323-gateway voip h323-id name
Designate a antecedent IP abode for the articulation gateway.
Router(config-if)#h323-gateway voip bind srcaddr ip-address
This command sets the antecedent IP abode to be acclimated for this gateway. The IP
address is acclimated for approachable H.323 traffic, which includes H.225, H.245, and
RAS messages. You do not accept to affair this command on the interface that
you authentic as the articulation aperture interface (although it ability be added convenient
to do so). Use this command on the interface that contains the IP address
to which you appetite to bind (for example, a loopback interface).
Configuring Codecs on an H.323 Gateway
Normally you configure alone one codec back you configure a punch associate on a gateway.
However, you can configure a prioritized account of codecs to access the anticipation of
establishing a affiliation amid endpoints during the H.245 barter phase.
Codec-order canning is enabled by absence in Cisco gateways active Cisco IOS
Release 12.3(1) and later. No added agreement is needed.
Step 3. To configure codec negotiation, you charge aboriginal actualize a codec articulation chic and
populate with a account of codecs in adjustment of their preference.
Enter voice-class agreement approach and accredit an identification tag number
for this codec articulation class.
Router(config)#voice chic codec tag
This command alone creates the articulation chic for codec alternative alternative and
assigns an identification tag. Use the codec alternative command to specify
the ambit of the articulation class, and use the voice-class codec dial-peer
command to administer the articulation chic to a VoIP punch peer.
Specify a account of adopted codecs to use on a punch peer.
Router(config-class)#codec alternative amount codec-type [bytes payloadsize]
Table 5-1 capacity the syntax options for this command.
Chapter 5: Examining VoIP Gateways and Aperture Control Protocols 265
Note Usually this footfall is the name of the gateway, with the attendant area name
appended, for example: name@domainname.
Table 5-1 codec alternative Syntax Description
Value The adjustment of preference, with 1 actuality the best adopted and 14 being
the atomic preferred
codec-type The codec preferred. Values are as follows:
clear-channel: Clear Channel 64,000 bps
g711alaw: G.711 a-law 64,000 bps
g711ulaw: G.711 mu-law 64,000 bps
g723ar53: G.723.1 ANNEX-A 5300 bps
g723ar63: G.723.1 ANNEX-A 6300 bps
g723r53: G.723.1 5300 bps
g723r63: G.723.1 6300 bps
g726r16: G.726 16,000 bps
g726r24: G.726 24,000 bps
g726r32: G.726 32,000 bps
g728: G.728 16,000 bps
g729abr8: G.729 ANNEX-A and B 8000 bps
g729br8: G.729 ANNEX-B 8000 bps
g729r8: G.729 8000 bps
gsmamr-nb: Enables GSMAMR codec capability
gsmefr: Global System for Mobile Communications Enhanced Full Rate
(GSMEFR) 12,200 bps
gsmfr: Global System for Mobile Communications (GSM) Full Rate
(GSMFR) 13,200 bps
ilbc: internet Low Bit amount Codec (iLBC) at 13,330 bps or 15,200 bps
transparent: Enables codec capabilities to be anesthetized transparently
between endpoints (Note: The cellophane keyword is not supported
when the call-start command is configured.)
bytes payload-size (Optional) Cardinal of bytes you specify as the articulation burden of each
frame. Values depend on the codec blazon and the packet articulation protocol.
Enter dial-peer agreement approach for the VoIP punch peer.
Router(config)#dial-peer articulation tag voip
Specify a distinct codec or accredit the ahead configured codec selection
preference account to the VoIP punch peer.
266 Authorized Self-Study Guide: Cisco Articulation over IP (CVOICE)
To specify a distinct codec
Router(config-dial-peer)#codec {clear-channel | g711alaw | g711ulaw |
g723ar53 | g723ar63 | g723r53 | g723r63 | g726r16 | g726r24 | g726r32 |
g726r53 | g726r63 | g728 | g729abr8 | g729ar8 | g729br8 | g729r8 |
gsmefr | gsmfr} [bytes payload_size]
Tuning H.323 Timers
The aftermost allotment of the book requires you to acclimatize some of the H.323 timers to accommodated network
specifications.
Step 4. Acclimatize H.225 timers.
Create an H.323 articulation chic and access articulation chic agreement mode.
Router(config)#voice chic h323 tag
To set the H.225 TCP authorize abeyance amount for VoIP punch peers, configure
the H.323 TCP authorize abeyance value.
Router(config-class)#h225 abeyance tcp authorize seconds
The cardinal of abnormal for the abeyance ambit is 0 to 30. The absence is 15. If
you specify 0, the H.225 TCP timer is disabled.
Configure the SETUP Acknowledgment Abeyance value.
Router(config-class)#h225 abeyance bureaucracy value
This command sets the abeyance value, in seconds, for the acknowledgment of the outgoing
SETUP message. Range: 0 to 30. Default: 15.
Enter dial-peer agreement approach for the VoIP punch peer.
Router(config)#dial-peer articulation tag voip
Assign the ahead configured H.323 articulation chic to this VoIP punch peer.
Router(config-dial-peer)#voice-class h323 tag
Enter voice-service agreement approach and specify a voice-encapsulation
type.
Router(config)#voice account {pots | voatm | vofr | voip}
Enable the H.323 articulation account agreement commands.
Router(conf-voi-serv)#h323
To set a timer for an abandoned alarm connection, change the Abandoned Timer for concurrent
calls.
Router(conf-serv-h323)#h225 abeyance tcp call-idle {value amount | never}
The afterward is a description of the syntax:
■ amount value: The abeyance value, in minutes. The ambit is 0 to 1440. The
default is 10. If you specify 0, the timer is disabled, and the TCP connection
is bankrupt anon afterwards all the calls are cleared.
Chapter 5: Examining VoIP Gateways and Aperture Control Protocols 267
■ never: The affiliation is maintained assuredly or until the added endpoint
closes it.
This command specifies the time to advance an accustomed H.225 TCP connection
when there are no calls on that connection. If the timer expires, the
connection is closed. If the timer is active and any new alarm is fabricated on that
connection, the timer stops. Back all the calls are austere on that connection,
the timer starts again.
H.323 Complete Configuration
Example 5-1 illustrates the complete H.323 agreement archetype ahead described.
Example 5-1 H.323 Agreement Example
268 Authorized Self-Study Guide: Cisco Articulation over IP (CVOICE)
Router(config)#voice account voip
Router(conf-voi-serv)#h323
Router(conf-voi-serv)#no shutdown
Router(config)#interface loopback 0
Router(config-if)#ip abode 10.10.1.1 255.255.255.0
Router(config-if)#h323-gateway voip interface
Router(config-if)#h323-gateway voip h323-id gw1
Router(config-if)#h323-gateway voip bind srcaddr 10.10.1.1
Router(config)#voice chic codec 100
Router(config-class)#codec alternative 1 g711alaw
Router(config-class)#codec alternative 2 g729br8
Router(config)#dial-peer articulation 500 voip
Router(config-dial-peer)#voice-class codec 100
Or
Router(config-dial-peer)#codec g711alaw
Router(config)#voice chic h323 600
Router(config-class)#h225 abeyance tcp authorize 10
Router(config-class)#h225 abeyance bureaucracy 10
Router(config)#dial-peer articulation 500 voip
Router(config-dial-peer)#voice-class h323 600
Router(config)#voice account voip
Router(conf-voi-serv)#h323
Router(conf-serv-h323)#h225 abeyance tcp call-idle never