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New Member

Max Forward Hops to DN value?

Hi guys,

If anyone tried to change the value of "Max Forward Hops to DN" in the service parameters before?

what is the reasonable value that we can set instead of the default 12.

Reason for asking this is because my client got a requirement that, Phone A forward to Phone B

on busy and no answer, Phone B forward to Phone A on busy and no answer. Obviously this going

to lead to call forward loops.

I'm thinking to set the "max forward hops to dn" value to 1, which theoretically should prevent

call loop from happen, but i'm wondering will that cause other side effect? will Unity or other phone

features will affected by this value?

Thanks

Regards,

Alex

Everyone's tags (4)
4 ACCEPTED SOLUTIONS

Accepted Solutions
Cisco Employee

Re: Max Forward Hops to DN value?

That parameter would affect all DNs. This would include those used for other functions. I would advise not changing it to 1 but to try and change it to 4 or 5.

-Felipe

Cisco Employee

Re: Max Forward Hops to DN value?

Yes, Unity might be affected if phone A is CFA to phone b and phone b  is CFA to VM.

I would say to set this up to 4 might be a good config, just to avoid the previous scenario or CTI ports CFA scenario, however 12 is the default, and this should not cause any loop as this CFA processing is being made at a 'call process level' so it will not even try to ring the phone or anything like that, it will just check the CF list and perform a desicion based on that list, if the destination phone is CFA to another then it will check the CF list again and make another desicion, if you take a CCM trace you will see that this is made in a few miliseconds.

Christian Nuche

PDI HD Team.

Hall of Fame Super Red

Re: Max Forward Hops to DN value?uys!)

Hi Alex,

Just to add a note to the great tips from Felipe and Christian (+5 each guys!)

Here are the notes for Call Forward Loop Detection.

Call Forward All Loop Prevention and Breakout

Cisco Unified Communications Manager prevents Call Forward All activation on the phone when a Call Forward All loop is identified. For example, Cisco Unified Communications Manager identifies a call forward loop when the user presses the CFA softkey on the phone with directory number 1000 and enters 1001 as the CFA destination, and 1001 has forwarded all calls to directory number 1002, which has forwarded all calls to directory number 1003, which has forwarded all calls to 1000. In this case, Cisco Unified Communications Manager identifies that a loop occurs and prevents CFA activation on the phone with directory number 1000.

Call Forward All loops do not impact call processing because Cisco Unified Communications Manager supports CFA loop breakout, which ensures that if a CFA loop is identified, the call goes through the entire forwarding chain, breaks out of the Call Forward All loop, and completes as expected, even if CFNA, CFB, or other forwarding options are configured along with CFA for one of the directory numbers in the forwarding chain. For example, the user for the phone with directory number 1000 forwards all calls to directory number 1001, which has forwarded all calls to directory number 1002, which has forwarded all calls to directory number 1000, thus creating a CFA loop. In addition, directory number 1002 has configured CFNA to directory number 1004. The user at the phone with directory number 1003 calls directory number 1000, which forwards to 1001, which forwards to 1002. Cisco Unified Communications Manager identifies a CFA loop, and the call, which breaks out of the loop, tries to connect to directory number 1002. If the No Answer Ring Duration timer expires before the user for the phone with directory number 1002 answers the call, Cisco Unified Communications Manager forwards the call to directory number 1004.

For a single call, Cisco Unified Communications Manager may identify multiple Call Forward All loops and attempts to connect the call after each loop is identified.

Cisco Unified Communications Manager Administration Configuration Tips

If Call Forward All activation occurs in Cisco Unified Communications Manager Administration or the Cisco Unified Communications Manager User Options, Cisco Unified Communications Manager does not prevent the CFA loop.

***If the same directory number exists in different partitions, for example, directory number 1000 exists in partitions 1 and 2, Cisco Unified Communications Manager allows the CFA activation on the phone.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucmbe/rel_notes/7_0_2/cucmbe-rel_notes-702.html#wp581544

Hope this helps!

Rob

Cisco Employee

Re: Max Forward Hops to DN value?

Check the "use personal preferences option" in the HP for the CFB and CFNA, and in the DNs set the CF no coverage to VM in order to achieve what you want.

HTH

java

If this helps, please rate

www.cisco.com/go/pdihelpdesk

HTH

java

if this helps, please rate

www.cisco.com/go/pdi
6 REPLIES
Cisco Employee

Re: Max Forward Hops to DN value?

That parameter would affect all DNs. This would include those used for other functions. I would advise not changing it to 1 but to try and change it to 4 or 5.

-Felipe

Cisco Employee

Re: Max Forward Hops to DN value?

Yes, Unity might be affected if phone A is CFA to phone b and phone b  is CFA to VM.

I would say to set this up to 4 might be a good config, just to avoid the previous scenario or CTI ports CFA scenario, however 12 is the default, and this should not cause any loop as this CFA processing is being made at a 'call process level' so it will not even try to ring the phone or anything like that, it will just check the CF list and perform a desicion based on that list, if the destination phone is CFA to another then it will check the CF list again and make another desicion, if you take a CCM trace you will see that this is made in a few miliseconds.

Christian Nuche

PDI HD Team.

Hall of Fame Super Red

Re: Max Forward Hops to DN value?uys!)

Hi Alex,

Just to add a note to the great tips from Felipe and Christian (+5 each guys!)

Here are the notes for Call Forward Loop Detection.

Call Forward All Loop Prevention and Breakout

Cisco Unified Communications Manager prevents Call Forward All activation on the phone when a Call Forward All loop is identified. For example, Cisco Unified Communications Manager identifies a call forward loop when the user presses the CFA softkey on the phone with directory number 1000 and enters 1001 as the CFA destination, and 1001 has forwarded all calls to directory number 1002, which has forwarded all calls to directory number 1003, which has forwarded all calls to 1000. In this case, Cisco Unified Communications Manager identifies that a loop occurs and prevents CFA activation on the phone with directory number 1000.

Call Forward All loops do not impact call processing because Cisco Unified Communications Manager supports CFA loop breakout, which ensures that if a CFA loop is identified, the call goes through the entire forwarding chain, breaks out of the Call Forward All loop, and completes as expected, even if CFNA, CFB, or other forwarding options are configured along with CFA for one of the directory numbers in the forwarding chain. For example, the user for the phone with directory number 1000 forwards all calls to directory number 1001, which has forwarded all calls to directory number 1002, which has forwarded all calls to directory number 1000, thus creating a CFA loop. In addition, directory number 1002 has configured CFNA to directory number 1004. The user at the phone with directory number 1003 calls directory number 1000, which forwards to 1001, which forwards to 1002. Cisco Unified Communications Manager identifies a CFA loop, and the call, which breaks out of the loop, tries to connect to directory number 1002. If the No Answer Ring Duration timer expires before the user for the phone with directory number 1002 answers the call, Cisco Unified Communications Manager forwards the call to directory number 1004.

For a single call, Cisco Unified Communications Manager may identify multiple Call Forward All loops and attempts to connect the call after each loop is identified.

Cisco Unified Communications Manager Administration Configuration Tips

If Call Forward All activation occurs in Cisco Unified Communications Manager Administration or the Cisco Unified Communications Manager User Options, Cisco Unified Communications Manager does not prevent the CFA loop.

***If the same directory number exists in different partitions, for example, directory number 1000 exists in partitions 1 and 2, Cisco Unified Communications Manager allows the CFA activation on the phone.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucmbe/rel_notes/7_0_2/cucmbe-rel_notes-702.html#wp581544

Hope this helps!

Rob

New Member

Re: Max Forward Hops to DN value?

Hi Guys,


Thanks for the all the reply, appreciated that.

is there any way to achieve such requirement without causing a loop?

may be using a hunt group?

what i can think of is create hunt pilot for Phone A and Phone B

which contain only one member (phone that going to forward too)

e.g Phone A have a 1122 hunt pilot member of Phone B, and

Phone B have a 2211 hunt pilot member of Phone A.

on CFB and CFNA of Phone A set to 1122, and Phone B set to 2211.

will that workable?

The requirement also need the call to end in the voicemail of the original

phone but not the forwarded to phone. will this be possible to achieve

using "Forward hunt no answer and busy" field in Hunt Pilot?

Again, Thanks

Regards,

Alex

Cisco Employee

Re: Max Forward Hops to DN value?

Check the "use personal preferences option" in the HP for the CFB and CFNA, and in the DNs set the CF no coverage to VM in order to achieve what you want.

HTH

java

If this helps, please rate

www.cisco.com/go/pdihelpdesk

HTH

java

if this helps, please rate

www.cisco.com/go/pdi
New Member

Re: Max Forward Hops to DN value?

Thanks Java for the reply.

I've manage to achieve what i wanted after using hunt pilot and tweak with the

hunt pilot setting.

Thanks guys!

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