SRST/MGCP Failover Issues

Unanswered Question
Jun 18th, 2008
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Hey,


So here is my current configuration.


application

global

service alternate default

!

ccm-manager fallback-mgcp

ccm-manager redundant-host X.X.X.X

ccm-manager mgcp

ccm-manager config server X.X.X.X

!

mgcp

mgcp call-agent X.X.X.X service-type mgcp version 0.1

mgcp rtp unreachable timeout 1000 action notify

mgcp modem passthrough voip mode nse

mgcp package-capability rtp-package

no mgcp package-capability res-package

mgcp package-capability sst-package

no mgcp package-capability fxr-package

mgcp package-capability pre-package

no mgcp timer receive-rtcp

mgcp sdp simple

mgcp fax t38 inhibit

mgcp rtp payload-type g726r16 static

mgcp bind control source-interface GigabitEthernet0/0

mgcp bind media source-interface GigabitEthernet0/0

!

mgcp profile default

!

call-manager-fallback

secondary-dialtone 9

max-conferences 8 gain -6

transfer-system full-consult

limit-dn 7940 2

limit-dn 7960 2

ip source-address X.X.X.X port 2000

max-ephones 20

max-dn 32

dialplan-pattern 1 972....... extension-length 4

access-code pri 9 direct-inward-dial

!

dial-peer voice 100 pots

service mgcpapp

incoming called-number .

port 0/0/1:23

!

dial-peer voice 101 pots

service mgcpapp

incoming called-number .

port 0/0/0:23

!

dial-peer voice 200 pots

description ** Primary - Incoming Call Dial Peer **

incoming called-number .

direct-inward-dial

port 0/0/0:23

!

dial-peer voice 201 pots

description ** Secondary - Incoming Call Dial Peer **

incoming called-number .

direct-inward-dial

port 0/0/1:23

!

dial-peer voice 208 pots

description ** Primary - 10 Digit Dial Peer **

destination-pattern 9[2-9]..[2-9]......

port 0/0/0:23

!

dial-peer voice 209 pots

description ** Secondary - 10 Digit Dial Peer **

preference 1

destination-pattern 9[2-9]..[2-9]......

port 0/0/1:23


When I create ACLs to block traffic from the phone to the CM and from CM and the MGCP gateway, both the Phone registers to the SRST gateway and MGCP falls back.


I can make outbound calls fine. When I try an inbound call, I receive dialtone after making the call.


Unfortunately I do not have the debugs to show you but the 'show ccm-manager fallback' showed that it was Enabled/ON.


Any ideas why I am receiving dialtone after making an incoming call? Im sure some of that config is not needed but dont' know if its necessarily the problem, for example: the 'access-code pri' command...not needed but is it causing a problem?

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Michael Owuor Wed, 06/18/2008 - 21:34
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  • Cisco Employee,

Bryan,


The incoming calls are probably coming in on dial-peers 100 and 101. You can verify if this is the case by running 'debug voip ccapi inout' during the test. If that is indeed the case, then you could add the 'direct-inward-dial' command under those two dial-peers to fix the issue. And if you do, you could simplify the configuration by getting rid of dial-peers 200 and 201.


Hope this helps.


Regards,

Michael.

Bryan Geoghan Thu, 06/19/2008 - 04:37
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I bet that's it. I don't know why I didn't think about adding the 'direct-inward-dial' to those first 2 incoming dial-peers. I guess I was thinking those wouldn't be used since they have the 'service mgcpapp' and MGCP has failed over to H323. I will try that. In the meantime, if anyone has anymore ideas or agrees with this, I would appreciate hearing it. :)


Thanks

webstd.design Wed, 06/18/2008 - 22:39
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Can you show the ACL that test your SRST?

I had the same problem. As I suppose you should create translations for you incoming calls.

Bryan Geoghan Thu, 06/19/2008 - 04:35
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I pretty much have 2 ACLs. I have applied one on the phone port denying traffic between the phone and the two CMs. Then I have another ACL next to the CMS denying traffic between the CM and the MGCP gateway which causes the MGCP gateway to failover to H323.

webstd.design Thu, 06/19/2008 - 04:48
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can you show me this ACL config? because I'm confusing about selecting preferable network ports for RTP and MGCP traffic.

Bryan Geoghan Thu, 06/19/2008 - 04:50
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I'm just denying IP. But the ports would be:


RTP: UDP 16384 - 32767

MGCP: UDP 2427 - 2428 (just block both)


Again, I'm just doing this variation:


access-list 101 deny ip host X.X.X.X host X.X.X.X

access-list 101 permit ip any any

webstd.design Thu, 06/19/2008 - 06:37
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You said that you use 2 tips of ACL? Is it true? because I'm using ACL


access-list 111 deny tcp xxxxxx xxxxxx host xxxxxx eq 2000

access-list 111 deny tcp xxxxxx xxxxxx host xxxxxx eq 2000

access-list 111 deny tcp xxxxxx xxxxxx host xxxxxx eq 2428

access-list 111 deny tcp xxxxxx xxxxxx host xxxxxx eq 2428

access-list 111 deny udp xxxxxx xxxxxx host xxxxxx eq 2427

access-list 111 deny udp xxxxxx xxxxxx host xxxxxx eq 2427

access-list 111 permit ip any any



And as a result phones registers on GATEWAY but GATEWAY doesn't go to the fallback mode.


Should I block all port for host?

webstd.design Thu, 06/19/2008 - 06:39
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access-list 101 deny ip host "IP addres of gateway" host "IP address of callmanager" access-list 101 permit ip any any


IS IT RIGHT?

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