Configuring Voice over HDLC

The following two different kinds of dial peers pertain to VoHDLC:

• POTS---Dial peer connected via a traditional telephony network. POTS dial peers point to a particular voice port on a voice network device.

• HDLC---Dial peer connected back-to-back with the Cisco MC3810. HDLC peers point to specific voice-network devices, normally a second Cisco MC3810.

NoteThe configuration for HDLC dial peers is very similar to the dial-peer configuration for Frame Relay or ATM. The term HDLC dial peer is used here because in most cases, the peer is back-to-back and normally on the same network.

POTS dial peers associate a telephone number with a particular voice port so that incoming calls for that telephone number can be received and outgoing calls can be placed. HDLC peers point to specific voice-network devices so that incoming calls can be received and outgoing calls can be placed. Both POTS and HDLC dial peers are needed to establish VoHDLC connections if you want to both send and receive calls. Establishing two-way communication using VoHDLC requires establishing a specific voice connection between two defined endpoints.

The following sections describe how to configure POTS and HDLC dial peers.

To configure POTS dial peers, use the following commands beginning in global configuration mode:

:

	Command	Purpose
Step1	Router(config)# dial-peer voice number pots	Defines a POTS dial peer and enters dial-peer configuration mode. All subsequent commands that you enter in dial-peer configuration mode before you exit will apply to this dial peer. The number tag value identifies the dial peer and must be unique on the Cisco MC3810. Do not duplicate a specific number tag.
Step2	Router(config-dial-peer)# destination-pattern string	Configures the dial peer destination pattern. The string argument is a series of digits that specify the E.164 or private dialing plan telephone number. Valid entries are the digits 0-9 and the letters A-D. The following special characters can be entered in the string: The star character (*) and the pound sign (#) that appear on standard touch-tone dial pads can be used in any dial string. However, these characters cannot be used as leading characters in a string (for example, *650). The period (.) can be entered any time, and is used as a wildcard character. The comma (,) can be used only in prefixes, and is used to insert a 1-second pause or a delay.
Step3	Router(config-dial-peer)# port slot/port	Associate this POTS dial peer with a specific logical dial interface. Enter the slot/port number of the voice port connected to the POTS dial peer.
Step4	Router(config-dial-peer)# forward-digits {num-digit | all}	(Optional) If you will use the digit-forwarding feature, configure the digit-forwarding method that will be used on the dial peer.
Step5	Router(config-dial-peer)# prefix string	(Optional) If the forward-digits feature was not configured in the last step, assign the dialed digits prefix for the dial peer.

To configure additional POTS dial peers, exit dial-peer configuration mode by entering the exit command, and repeat the previous steps.

To configure VoHDLC dial peers, use the following commands beginning in global configuration mode:

:

	Command	Purpose
Step1	Router(config)# dial-peer voice tag vohdlc	Defines a dial peer for VoHDLC and enters dial-peer configuration mode. All subsequent commands that you enter in dial-peer configuration mode before you exit will apply to this dial peer. The number tag value identifies the dial peer and must be unique on the Cisco MC3810. Do not duplicate a specific number tag.
Step2	Router(config-dial-peer)# destination-pattern string	Configures the dial peer destination pattern. The same restrictions for the string listed in the POTS dial-peer configuration also apply to the VoHDLC destination pattern.
Step3	Router(config-dial-peer)# session target interface serial-port-number	Configures the HDLC session target for the dial peer. For the serial-port-number value, enter either 0 and 1.
Step4	Router(config-dial-peer)# preference value	(Optional) Configures a preference for the VoHDLC dial peer. The value is a number from 0-10 where the lower the number, the higher the preference.
Step5	Router(config-dial-peer)# alt-dial string	(Optional) Configures the alternate dial-out string when configuring on-net-to-off-net alternative dialing.

To configure additional HDLC dial peers, exit dial-peer configuration mode by entering the exit command, and repeat the previous steps.

NoteYou can also create a voice class to configure trunk conditioning values for the idle and out-of-service (OOS) states, and then assign the voice class to the VoHDLC dial peer. For more information, see the "Configuring Voice-Related Support Features" chapter.

To configure a VoHDLC dial peer to support Cisco-trunk permanent (private line) calls, use the following commands beginning in global configuration mode:

	Command	Purpose
Step1	Router(config)# dial-peer voice number vohdlc	Defines a VoHDLC dial peer and enters dial-peer configuration mode.
Step2	Router(config-dial-peer)# destination-pattern string	Configures the dial peer's destination pattern.
Step3	Router(config-dial-peer)# session target interface	Configures the HDLC session target for the dial peer.
Step4	Router(config-dial-peer)# session protocol cisco-switched	Configures the session protocol to support Cisco-trunk calls. The cisco-switched option is the default setting, and entering this command is not required.
Step5	Router(config-dial-peer)# codec type [bytes bytes]	Specifies the voice coder rate of speech and payload size for the dial peer. The default dial peer codec is g729r8. Note that the Cisco MC3810 is limited to a maximum of 12 calls when using g729r8; to support up to 24 calls on the Cisco MC3810, use g729ar8. Specifying the payload size by entering the bytes value is optional. Each codec type defaults to a different payload size if you do not specify a value. To obtain a list of the default payload sizes, enter the codec command and the bytes option followed by a question mark (?). NoteOn the Cisco MC3810, you can also assign codec values to the voice port. When you configure the codec type for regular switched voice calls, you must set the codec type on the Cisco MC3810 voice port. When you configure the codec for permanent calls (the cisco-trunk keyword), you must configure the codec type on the dial peer. You cannot specify the payload size on the voice port.
Step6	Router(config-dial-peer)# dtmf-relay	(Optional) If the codec type is a low bit-rate codec such as g729 or g723, specifies support for DTMF relay to improve end-to-end transport of DTMF tones. DTMF tones do not always propagate reliably with low bit-rate codecs. DTMF relay is disabled by default.
Step7	Router(config-dial-peer)# signal-type {cas | cept | ext-signal | transparent}	Defines the flavor of the ABCD signalling packets that are generated by the voice port and sent to the data network. The signal type must be configured to the same setting at both ends of the permanent voice call. Enter cas to support CAS. Enter cept to support the European CEPT standard (related to MELCAS). Enter ext-signal to indicate that ABCD signalling packets should not be sent, for configurations where the line signalling information is carried externally to the voice port. Enter transparent (for digital T1/E1 interfaces on the Cisco MC3810 only) to read the ABCD signalling bits directly from the T1/E1 interface without interpretation, and to pass them transparently to the data network (this is also known as transparent FRF.11 signalling).
Step8	Router(config-dial-peer)# no vad	(Optional) Disables voice activity detection (VAD) on the dial peer. This command is enabled by default.
Step9	Router(config-dial-peer)# sequence-numbers	(Optional) Enables the voice sequence number if required for your configuration. This command is disabled by default.
Step10	Router(config-dial-peer)# preference value	(Optional) Configures a preference for the VoHDLC dial peer. The value is a number from 0-10 where the lower the number, the higher the preference in hunt groups.
Step11	Router(config-dial-peer)# fax rate {2400 | 4800 | 7200 | 9600 | 14400 | disable | voice}	(Optional) Configures the transmission speed (in bits per second) at which a fax will be sent to the dial peer. The default is voice, which specifies the highest possible transmission speed allowed by the voice rate.

To configure another VoHDLC dial peer for Cisco-trunk (private line) calls, exit dial-peer configuration mode and repeat Steps 1 through 11.

Cisco MC3810 No. 1 Configuration

interface Serial1 point-to-point
 ip address 5.5.5.1 255.0.0.0
 no keepalive
 ipx network 2222
 ipx accounting
 voice-encap 512
 clockrate 64000
 
ip classless
 
line con 0
 exec-timeout 0 0
line aux 0
line vty 0 4
 login
 
 
voice-port 1/1
 
 dial-peer voice 1 pots
 destination-pattern 3388801
 port 1/1
 
dial-peer voice 2 pots
 destination-pattern 3388802
 port 1/2
 
dial-peer voice 44 vohdlc
 destination-pattern 348....
 session target Serial1
 
end
 
 

Cisco MC3810 No. 2 Configuration

interface Serial1 point-to-point
 ip address 5.5.5.2 255.0.0.0
 no keepalive
 ipx network 2222
 ipx accounting
 voice-encap 512
 clockrate 64000
 
ip classless
 
line con 0
 exec-timeout 0 0
line aux 0
line vty 0 4
 login
 
 
voice-port 1/1
 
 dial-peer voice 1 pots
 destination-pattern 3488803
 port 1/1
 
dial-peer voice 2 pots
 destination-pattern 3488804
 port 1/2
 
dial-peer voice 40 vohdlc
 destination-pattern 338....
 session target Serial1
 
end