H323 gateway with SRST problem

[russell-b]

Recently I changed one of our SRST ISDN gateways (15.1(1)T4) from MGCP to H323 to alleviate problem of external calls dropping during WAN outage. This seemed to fix dropping-out problem but we soon discovered that call transfers were now failing. To overcome this I added MTP to H323 trunk on Callmanager (8.0), this fixed transfer problem. Unfortunately now when WAN outage occurs external calls are again dropping out. Can anyone please offer some advice on how to best approach this dilemma?

[Chris Deren]

You should not be using MTP with H323 controlled PRI. Can you post your config?  Are you using faststart by any chance?

Chris

[russell-b]

HI Chris

Relevant config as follows. using slow start to remove the reliance on CUCM MTP.

x
!
boot-start-marker
boot system flash:c2951-universalk9-mz.SPA.151-1.T4.bin
boot-end-marker
!
card type e1 0 0
x
!
clock timezone GMT+2 2
network-clock-participate wic 0
network-clock-select 1 E1 0/0/0
!
x
!
isdn switch-type primary-net5
!
!
trunk group ISDN
hunt-scheme longest-idle
translation-profile incoming DID
translation-profile outgoing OUTBOUND
!
voice-card 0
dspfarm
dsp services dspfarm
!
!
voice rtp send-recv
!
voice service voip
allow-connections h323 to h323
no supplementary-service h450.2
no supplementary-service h450.3
fax protocol t38 version 0 ls-redundancy 0 hs-redundancy 0 fallback none
h323
  no h225 timeout keepalive
  call start slow
modem passthrough nse codec g711alaw
!
voice class codec 10
codec preference 1 g711alaw
codec preference 2 g711ulaw
codec preference 3 g729r8
codec preference 4 ilbc
!
!
!
!
voice translation-rule 1
rule 1 /^21\(..\)/ /2711\1/
rule 2 /^20\(..\)/ /2710\1/
rule 3 /^22\(..\)/ /2712\1/
!
voice translation-rule 2
rule 1 /^000\(..\)/ /00\1/
rule 2 /^001\(..\)/ /01\1/
rule 3 /^002\(..\)/ /02\1/
rule 4 /^003\(..\)/ /03\1/
rule 5 /^004\(..\)/ /04\1/
rule 6 /^005\(..\)/ /05\1/
rule 7 /^006\(..\)/ /06\1/
rule 8 /^007\(..\)/ /07\1/
rule 9 /^008\(..\)/ /08\1/
rule 10 /^009\(..\)/ /09\1/
rule 11 /^01\(..\)/ /1\1/
!
!
voice translation-profile DID
translate called 1
!
voice translation-profile OUTBOUND
translate called 2
!
!
!
application
global
  service alternate Default
!
!
license udi pid CISCO2951/K9 sn x
hw-module pvdm 0/0
!
!
!
x
!
!
controller E1 0/0/0
framing NO-CRC4
pri-group timeslots 1-31
!
ip tftp source-interface GigabitEthernet0/1
ip ssh version 2
!
x
!
!
!
!
!
!
!
interface GigabitEthernet0/0
description $ETH-LAN$$ETH-SW-LAUNCH$$INTF-INFO-GE 0/0$
no ip address
shutdown
duplex auto
speed auto
!
interface GigabitEthernet0/1
description --- Connection to ZA-JNB-SWC-01: Gi 0/44 ---
ip address 10.48.11.250 255.255.255.0
duplex auto
speed auto
service-policy output SRST
!
interface GigabitEthernet0/2
no ip address
shutdown
duplex auto
speed auto
!
interface Serial0/0/0:15
no ip address
encapsulation hdlc
isdn switch-type primary-net5
isdn incoming-voice voice
trunk-group ISDN
no cdp enable
!
ip forward-protocol nd
!
ip http server
ip http authentication local
ip http secure-server
ip http timeout-policy idle 60 life 86400 requests 10000
!
ip route 0.0.0.0 0.0.0.0 10.48.11.254
!
x
!
x
!
!
x
!
!
voice-port 0/0/0:15
!
voice-port 0/1/0
echo-cancel coverage 64
cptone ZA
shutdown
!
voice-port 0/1/1
!
voice-port 0/1/2
!
voice-port 0/1/3
!
!
no mgcp package-capability res-package
no mgcp timer receive-rtcp
!
sccp local GigabitEthernet0/1
sccp ccm 10.0.20.248 identifier 2 version 7.0
sccp ccm 10.15.20.247 identifier 1 version 7.0
sccp
!
sccp ccm group 1
bind interface GigabitEthernet0/1
associate ccm 1 priority 1
associate ccm 2 priority 2
associate profile 1 register JNB-VGW01-MTP
associate profile 2 register JNB-VGW01-TX
!
dspfarm profile 2 transcode
codec pass-through
codec ilbc
codec g722-64
codec g729br8
codec g729r8
codec g729abr8
codec g729ar8
codec g711alaw
codec g711ulaw
maximum sessions 6
associate application SCCP
!
dspfarm profile 1 mtp
codec g729r8
maximum sessions software 100
associate application SCCP
shutdown
!
dial-peer voice 100 pots
trunkgroup ISDN
description International Dial-peer
destination-pattern 000.T
forward-digits all
!
dial-peer voice 101 pots
trunkgroup ISDN
description South Africa FNN Dial-peer
destination-pattern 00[1-9]........
forward-digits all
!
x
!
dial-peer voice 300 pots
trunkgroup ISDN
description FallBack Inbound Dial-peer
incoming called-number .
direct-inward-dial
!
dial-peer voice 400 voip
preference 1
destination-pattern 2710..
session target ipv4:10.15.20.247
dtmf-relay rtp-nte
!
dial-peer voice 401 voip
preference 2
destination-pattern 2710..
session target ipv4:10.0.20.248
dtmf-relay rtp-nte
!
dial-peer voice 500 voip
description --Incoming Calls from CM--
preference 1
session target ipv4:10.15.20.247
incoming called-number .
voice-class codec 10
dtmf-relay rtp-nte
!
dial-peer voice 501 voip
description --Incoming Calls from CM--
preference 2
session target ipv4:10.0.20.248
incoming called-number .
voice-class codec 10
dtmf-relay rtp-nte
!
dial-peer voice 402 voip
preference 3
destination-pattern 2710..
session target ipv4:10.48.11.250
dtmf-relay rtp-nte
!
dial-peer voice 102 pots
trunkgroup ISDN
description Info Services
destination-pattern 01....
forward-digits all
!
!
!
!
gatekeeper
shutdown
!
!
call-manager-fallback
max-conferences 8 gain -6
transfer-system full-consult
timeouts interdigit 5
ip source-address 10.48.11.250 port 2000
max-ephones 100
max-dn 100
system message primary SRST Mode Operating
dialplan-pattern 2 20.. extension-length 6 extension-pattern 2710..
transfer-pattern 0.T
transfer-pattern .T
moh music-on-hold.au
multicast moh 239.1.1.1 port 16386
time-zone 29
date-format dd-mm-yy
!
x
!
x
!
x

[Tracy Larson · Accepted solution]

I think that even with H323 controlled gateways you will have to issue the "call preserve" command so that calls will not drop during WAN link failures.

If you are using Cisco Unified Communications Manager, you must enable

the Allow Peer to Preserve H.323 Calls parameter from the Service Parameters window.

The call preserve command causes the gateway to ignore socket closure or socket errors on H.225.0 or

H.245 connections for active calls, thus allowing the socket to be closed without tearing down calls using

those connections.

Example of H.323 VoIP Call Preservation for All Calls

The following configuration example enables H.323 VoIP call preservation for all calls:

voice service voip

h323

call preserve

http://www.cisco.com/en/US/docs/ios/12_3/vvf_c/cisco_ios_h323_configuration_guide/old_archives_h323/4gwconf.html

[russell-b]

Have modified config as follows and have removed MTP reliance from H323 trunk in CUCM.

!

voice service voip

allow-connections h323 to h323

fax protocol t38 version 0 ls-redundancy 0 hs-redundancy 0 fallback none

h323

no h225 timeout keepalive

call start slow

call preserve

modem passthrough nse codec g711alaw

!

[russell-b]

tested and now working with modified configuration above.

Thank you Tracy, Thank you Chris