Table Of Contents
NFAS with D-Channel Backup
This chapter describes how to implement the Non-Facility Associated Signaling (NFAS) with D-Channel Backup feature with two new switch types: DMS100 and NI2. ISDN NFAS allows a single D channel to control multiple ISDN PRI interfaces. You can configure a backup D channel for use when the primary NFAS D channel fails.
After you configure channelized T1 controllers for ISDN PRI, you only need to configure the NFAS primary D channel; its configuration is distributed to all the members of the associated NFAS group.
Note A controller configured with backup D channel loses one B channel.
Use of a single D channel to control up to 10 PRI interfaces can free one B channel on each interface to carry other traffic.
Any hard failure causes a switchover to the backup D channel and currently connected calls remain connected. The backup D channel cannot be used for data transfer.
Note On the Nortel dms100 switch, when a single D channel is shared, multiple PRI interfaces may be configured in a single trunk group. The additional use of alternate route indexing, which is a feature of the dms100 switch, provides a rotary from one trunk group to another. This enables the capability of building large trunk groups in a public switched network.
This feature was introduced.
This feature was implemented on the Cisco AS5850 platform.
NFAS network-side support was added.
Feature History for NFAS with D-Channel Backup
Finding Support Information for Platforms and Cisco IOS Software Images
Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.
Note For more information about related Cisco IOS voice features, see the following:
•"Overview of ISDN Voice Interfaces" on page 3
•Entire Cisco IOS Voice Configuration Library—including library preface and glossary, other feature documents, and troubleshooting documentation—at http://www.cisco.com/en/US/docs/ios/12_3/vvf_c/cisco_ios_voice_configuration_library_glossary/vcl.htm.
For a list of references cited in this chapter, see the "Additional References" section.
Prerequisites for Configuring NFAS with D-Channel Backup
•Perform the prerequisites that are listed in the "Prerequisites for Configuring an ISDN Voice Interface" section on page 15.
•Configure your router's channelized T1 controllers for ISDN, as described in the "Configuring ISDN PRI" section of the "Configuring Channelized E1 and Channelized T1" chapter in the Dial Solutions Quick Configuration Guide.
Restrictions for Configuring NFAS with D-Channel Backup
Restrictions are described in the Restrictions for Configuring ISDN Voice Interfaces, page 4. In addition, the following apply:
•NFAS is supported with only a channelized T1 controller and, as a result, is ISDN PRI capable.
•NFAS is supported across multiple T1 controllers installed on different slots only if the DSPs of those slots are of the same type. For example, if T1 controllers on slot 1 and slot 2 are combined to form an NFAS group with the T1 in slot 1 being primary, both slots must have the same type of DSP. If these two slots have different DSP types, only those calls using T1 on slot 1 will connect —all calls through T1 on slot 2 will fail with a disconnect cause of "Resource Unavailable/Unspecified (47)."
•The router must connect to either a 4ess, dms250, dms100, or National ISDN switch type. Table 47 shows applicable ISDN switch types and supported NFAS types.
Information about NFAS
Non-Facility Associated Signaling is a classification of signalling protocols that provide the signalling channel in a separate physical line from the bearer channels.
Note General information about ISDN voice interfaces is presented in the "Information About ISDN Voice Interfaces" section on page 4.
How to Configure NFAS with D-Channel Backup
Configuring NFAS on PRI Groups
To configure NFAS on PRI groups, perform the following steps.
Note When a backup NFAS D channel is configured and the primary NFAS D channel fails, rollover to the backup D channel is automatic and all connected calls stay connected. If the primary NFAS D channel recovers, the backup NFAS D channel remains active and does not switch over again unless the backup NFAS D channel fails.
2. configure terminal
4. pri-group timeslots nfas_d primary nfas_interface nfas_group
5. pri-group timeslots nfas_d backup nfas_interface nfas_group
6. pri-group timeslots 1-24 nfas_d none nfas_int nfas_group
7. exitDETAILED STEPS
Configuring a VoIP Dial Peer for NFAS Voice
To configure a VoIP dial peer for NFAS voice, perform the following steps.
Note Dial peers are used by the Cisco IOS voice stack for handling calls going from the PSTN to the VoIP side or vice versa. The dial-peer configuration for each NFAS controller should contain the primary of the NFAS group.
2. configure terminal
3. dial-peer voice voip
5. exitDETAILED STEPS
Disabling a Channel or Interface
To disable a channel or interface, perform the following steps.
Note You can disable a specified channel or an entire PRI, thus taking it out of service or put it into one of the other states that is passed in to the switch.
2. configure terminal
3. interface serial controller-number:timeslot
4. isdn service dsl b_channel state
5. isdn service dsl b_channel state
6. exitDETAILED STEPS
Verifying NFAS Configuration
To verify NFAS configuration, perform the following steps (listed alphabetically).
1. show dial-peer voice
2. show isdn nfas group
3. show isdn service
4. show isdn status
5. show running-config
Step 1 show dial-peer voice
Use this command to display the configuration information for dial peers.Router# show dial-peer voiceVoiceOverIpPeer1information type = voice,tag = 1, destination-pattern = `',answer-address = `', preference=0,numbering Type = `unknown'group = 1, Admin state is up, Operation state is down,incoming called-number = `', connections/maximum = 0/unlimited,DTMF Relay = disabled,modem passthrough = system,huntstop = disabled,in bound application associated: DEFAULTout bound application associated:permission :bothincoming COR list:maximum capabilityoutgoing COR list:minimum requirementtype = voip, session-target = `',technology prefix:settle-call = disabledip precedence = 0, UDP checksum = disabled,session-protocol = cisco, session-transport = udp, req-qos = best-efforacc-qos = best-effort,fax rate = voice, payload size = 20 bytesfax protocol = systemfax NSF = 0xAD0051 (default)codec = g729r8, payload size = 20 bytes,Expect factor = 0, Icpif = 20,Playout: Mode adaptive,Expect factor = 0,Max Redirects = 1, Icpif = 20,signaling-type = cas,CLID Restrict = disabledVAD = enabled, Poor QOV Trap = disabled,voice class perm tag = `'Connect Time = 0, Charged Units = 0,Successful Calls = 0, Failed Calls = 0,Accepted Calls = 0, Refused Calls = 0,Last Disconnect Cause is "",Last Disconnect Text is "",Last Setup Time = 0.
Step 2 show isdn nfas group
Use this command to display information about members of an NFAS group.Router# show isdn nfas group 1ISDN NFAS GROUP 1 ENTRIES:The primary D is Serial1/0:23.The backup D is Serial1/1:23.The NFAS member is Serial2/0:23.There are 3 total nfas members.There are 93 total available B channels.The primary D-channel is DSL 0 in state INITIALIZED.The backup D-channel is DSL 1 in state INITIALIZED.The current active layer 2 DSL is 1.
Step 3 show isdn service
Use this command to display information about ISDN channels and the service states.
Step 4 show isdn status
Use this command to display the status of all ISDN interfaces, including active layers, timer information, and switch-type settings.
Step 5 show running-config
Use this command to display the basic router configuration.
This section provides the following output examples:
Sample Output for the show isdn nfas group Command
The following three examples show D channel state changes when rollover occurs from the primary NFAS D channel to the backup D channel. The first example shows the output with the primary D channel in service and the backup D channel in standby.Router# show isdn nfas group 0ISDN NFAS GROUP 0 ENTRIES:The primary D is Serial1/0:23.The backup D is Serial1/1:23.The NFAS member is Serial2/0:23.There are 3 total nfas members.There are 70 total available B channels.The primary D-channel is DSL 0 in state IN SERVICE.The backup D-channel is DSL 1 in state STANDBY.The current active layer 2 DSL is 0.
The following example shows output during rollover. The configured primary D channel is in maintenance busy state and the backup D channel is waiting.Router# show isdn nfas group 0ISDN NFAS GROUP 0 ENTRIES:The primary D is Serial1/0:23.The backup D is Serial1/1:23.The NFAS member is Serial2/0:23.There are 3 total nfas members.There are 70 total available B channels.The primary D-channel is DSL 0 in state MAINTENANCE BUSY.The backup D-channel is DSL 1 in state WAIT.The current active layer 2 DSL is 1.
The following example shows output when rollover is complete. The configured primary D channel is now in standby and the backup D channel is in service.Router# show isdn nfas group 0ISDN NFAS GROUP 0 ENTRIES:The primary D is Serial1/0:23.The backup D is Serial1/1:23.The NFAS member is Serial2/0:23.There are 3 total nfas members.There are 70 total available B channels.The primary D-channel is DSL 0 in state STANDBY.The backup D-channel is DSL 1 in state IN SERVICE.The current active layer 2 DSL is 1.
Configuration Examples for NFAS with D-Channel Backup
NFAS Primary and Backup D Channels: Example
The following example configures ISDN PRI and NFAS on multiple T1 controllers of a Cisco 7500 series router. The D-channel of T1 1/0/0 is configured as primary D-channel and T1 1/0/1 is configured as backup D-channel. Once you configure the NFAS primary D channel, that channel is the only interface you see and have to configure.version 12.xservice timestamps debug datetime msec localtime show-timezoneservice timestamps log datetime msec localtime show-timezoneservice password-encryption!hostname travis-nas-01!aaa new-modelaaa authentication login default localaaa authentication login NO_AUTHENT noneaaa authorization exec default local if-authenticatedaaa authorization exec NO_AUTHOR noneaaa authorization commands 15 default local if-authenticatedaaa authorization commands 15 NO_AUTHOR noneaaa accounting exec default start-stop group tacacs+aaa accounting exec NO_ACCOUNT noneaaa accounting commands 15 default stop-only group tacacs+aaa accounting commands 15 NO_ACCOUNT noneenable secret 5 $1$LsoW$K/qBH9Ih2WstUxvazDgmY/!username admin privilege 15 password 7 06455E365E471D1C17username gmcmilla password 7 071824404D06140044username krist privilege 15 password 7 0832454D01181118!call rsvp-syncshelf-id 0 router-shelfshelf-id 1 dial-shelf!resource-pool disable!modem-pool Defaultpool-range 1/2/0-1/2/143,1/3/0-1/3/143!clock timezone CST -6clock summer-time CST recurring!ip subnet-zeroip domain-name cisco.comip name-server 172.22.53.210ip name-server 188.8.131.52ip name-server 184.108.40.206ip name-server 220.127.116.11!isdn switch-type primary-5essisdn voice-call-failure 0!controller T1 1/0/0framing esflinecode b8zspri-group timeslots 1-24 nfas_d primary nfas_interface 1 nfas_group 1description PacBell 3241933!controller T1 1/0/1framing esflinecode b8zspri-group timeslots 1-24 nfas_d backup nfas_interface 2 nfas_group 1description PacBell 3241933!interface Loopback0ip address 172.21.10.1 255.255.255.255!interface FastEthernet0/0/0ip address 172.21.101.20 255.255.255.0half-duplex!interface Serial1/0/0:23no ip addressip mroute-cacheisdn switch-type primary-5essisdn incoming-voice modemno cdp enable!interface Group-Async0no ip addressgroup-range 1/2/00 1/3/143!router eigrp 1network 172.21.0.0no eigrp log-neighbor-changes!ip classlessip route 0.0.0.0 0.0.0.0 172.21.101.1
ip http serverip http authentication aaa!snmp-server engineID local 0000000902000030F2F51400snmp-server community 5urf5h0p ROsnmp-server community 5crapmeta1 RWsnmp-server community SNMPv1 view v1default RO
POTS Dial-Peer Configuration: Example
The following example shows configuration of a POTS dial peer with the primary controller of an NFAS group:dial-peer voice 35 potsincoming called-number 45...destination-pattern 35...direct-inward-dialport 1/0/0:Dprefix 35
PRI Service State: Example
The following example reenables the entire PRI after it was disabled:isdn service dsl 0 b-channel 0 state 0
General ISDN References
•"ISDN Features Roadmap" on page 1—Describes how to access Cisco Feature Navigator; also lists and describes, by Cisco IOS release, ISDN features for that release
•"Overview of ISDN Voice Interfaces" on page 3—Describes relevant underlying technology; lists related documents, standards, MIBs, and RFCs; and describes how to obtain technical assistance
•"Additional References" section on page 64—Lists additional ISDN references
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