Hello,

Customer configured DNS and DHCP for the phone provisionning as stated here : https://help.mypurecloud.com/articles/phone-provisioning-dhcp-dns/
But they are challenging us on what will happen if the Edge that a phone (PureCloud SIP Phone actually) is trying to contact in order to get its configuration failed to answer ...
From my understanding, the second Edge will answer the request ... 
But how does that work ? Is it the phone that will send another request to the FQDN ? (and the DNS Roud-robin kick in and redirect the request to the second Edge) Or is it a functionality of the DHCP Option 160 that will retry to connect on the same FQDN ?

Cheers,
Valéry Chhoa
#SystemAdministration
#Telephony

------------------------------
Valery CHHOA
Genesys - Employees
------------------------------

Option 160 points to the FQDN, so DNS figures out which IP address is actually responding and will supply that IP address to the phone to use for the provisioning. All part of DNS functionality.

------------------------------
George Ganahl CCXP, GCP
Principal Technology Consultant
Genesys
------------------------------

Original Message:
Sent: 07-11-2019 16:59
From: Valery CHHOA
Subject: [SIP Phone provisionning] What happen if a one of the Edge is offline

Hello,

Customer configured DNS and DHCP for the phone provisionning as stated here : https://help.mypurecloud.com/articles/phone-provisioning-dhcp-dns/
But they are challenging us on what will happen if the Edge that a phone (PureCloud SIP Phone actually) is trying to contact in order to get its configuration failed to answer ...
From my understanding, the second Edge will answer the request ...
But how does that work ? Is it the phone that will send another request to the FQDN ? (and the DNS Roud-robin kick in and redirect the request to the second Edge) Or is it a functionality of the DHCP Option 160 that will retry to connect on the same FQDN ?

Cheers,
Valéry Chhoa
#SystemAdministration
#Telephony

------------------------------
Valery CHHOA
Genesys - Employees
------------------------------

Hello George,

Thanks for this answer. That’s what I explain to the customer but got challenged since the Network It admin replied that the DNS won’t know if one of the server is down. It’s only job is to reply the IPs in a round robin way for each FQDN request. It won’t ping the IP to check it’s alive or not.
And since I’m no expert on DNS or DHCP, I couldn’t argue with him ...

Envoyé de mon iPhone


Original Message------

Option 160 points to the FQDN, so DNS figures out which IP address is actually responding and will supply that IP address to the phone to use for the provisioning. All part of DNS functionality.

------------------------------
George Ganahl CCXP, GCP
Principal Technology Consultant
Genesys
------------------------------

Yeah, I have to retract on this one...I answered too quickly and not thoroughly.

When a request comes from the phone to DNS, DNS returns the next address in its list of Host A records for the FQDN. If that host does not respond to the phones provisioning request, the phone will ask again and get the next address in the list.

So, DNS just serves up IP addresses in round-robin fashion to each request that comes in. The phone has to know to request again instead of just failing and stopping there.

Which the supported phones do.

------------------------------
George Ganahl CCXP, GCP
Principal Technology Consultant
Genesys
------------------------------

Original Message:
Sent: 07-12-2019 03:25
From: Valery CHHOA
Subject: [SIP Phone provisionning] What happen if a one of the Edge is offline

Hello George,

Thanks for this answer. That's what I explain to the customer but got challenged since the Network It admin replied that the DNS won't know if one of the server is down. It's only job is to reply the IPs in a round robin way for each FQDN request. It won't ping the IP to check it's alive or not.
And since I'm no expert on DNS or DHCP, I couldn't argue with him ...

Envoyé de mon iPhone


Original Message------

Option 160 points to the FQDN, so DNS figures out which IP address is actually responding and will supply that IP address to the phone to use for the provisioning. All part of DNS functionality.

------------------------------
George Ganahl CCXP, GCP
Principal Technology Consultant
Genesys
------------------------------

If the phone is not capable of re-requesting, you could have a service that monitors the Edge availability and modifies the DNS records accordingly.


------------------------------
Anders Vejen
TDC Netdesign
------------------------------

Original Message:
Sent: 07-12-2019 08:58
From: George Ganahl
Subject: [SIP Phone provisionning] What happen if a one of the Edge is offline

Yeah, I have to retract on this one...I answered too quickly and not thoroughly.

When a request comes from the phone to DNS, DNS returns the next address in its list of Host A records for the FQDN. If that host does not respond to the phones provisioning request, the phone will ask again and get the next address in the list.

So, DNS just serves up IP addresses in round-robin fashion to each request that comes in. The phone has to know to request again instead of just failing and stopping there.

Which the supported phones do.

------------------------------
George Ganahl CCXP, GCP
Principal Technology Consultant
Genesys

Original Message:
Sent: 07-12-2019 03:25
From: Valery CHHOA
Subject: [SIP Phone provisionning] What happen if a one of the Edge is offline

Hello George,

Thanks for this answer. That's what I explain to the customer but got challenged since the Network It admin replied that the DNS won't know if one of the server is down. It's only job is to reply the IPs in a round robin way for each FQDN request. It won't ping the IP to check it's alive or not.
And since I'm no expert on DNS or DHCP, I couldn't argue with him ...

Envoyé de mon iPhone


Original Message------

Option 160 points to the FQDN, so DNS figures out which IP address is actually responding and will supply that IP address to the phone to use for the provisioning. All part of DNS functionality.

------------------------------
George Ganahl CCXP, GCP
Principal Technology Consultant
Genesys
------------------------------

Thanks George and Anders for the repies.

So all the managed phone should be able to request again if the first edge is unavailable.
Do you know if it's a built-in feature on each managed phone ? or global one linked to an RFC or functionality ?
I tried to search for this information on the PureCloud SIP Phone but didn't find anything.

Cheers,
Valéry

------------------------------
Valery CHHOA
Genesys - Employees
------------------------------

Original Message:
Sent: 07-12-2019 08:58
From: George Ganahl
Subject: [SIP Phone provisionning] What happen if a one of the Edge is offline

Yeah, I have to retract on this one...I answered too quickly and not thoroughly.

When a request comes from the phone to DNS, DNS returns the next address in its list of Host A records for the FQDN. If that host does not respond to the phones provisioning request, the phone will ask again and get the next address in the list.

So, DNS just serves up IP addresses in round-robin fashion to each request that comes in. The phone has to know to request again instead of just failing and stopping there.

Which the supported phones do.

------------------------------
George Ganahl CCXP, GCP
Principal Technology Consultant
Genesys

Original Message:
Sent: 07-12-2019 03:25
From: Valery CHHOA
Subject: [SIP Phone provisionning] What happen if a one of the Edge is offline

Hello George,

Thanks for this answer. That's what I explain to the customer but got challenged since the Network It admin replied that the DNS won't know if one of the server is down. It's only job is to reply the IPs in a round robin way for each FQDN request. It won't ping the IP to check it's alive or not.
And since I'm no expert on DNS or DHCP, I couldn't argue with him ...

Envoyé de mon iPhone


Original Message------

Option 160 points to the FQDN, so DNS figures out which IP address is actually responding and will supply that IP address to the phone to use for the provisioning. All part of DNS functionality.

------------------------------
George Ganahl CCXP, GCP
Principal Technology Consultant
Genesys
------------------------------