IMG 1010 - Ethernet Redundancy via Smart Probe

Overview:

Feature F-1675 Ethernet Link Redundancy via Smart-Probing enhances the IMG’s ability to initiate a switchover due to a failure in the IMG’s network. Currently the IMG employs a link based Ethernet Redundancy scheme. In the current scheme, the IMG would initiate a switch-over such as from interface Data 0 to Data 1 located on the rear of the IMG. With the addition of this feature the IMG can be configured to employ a probe-based detection scheme. In this scheme, the IMG would ‘probe’ a set of pre-configured endpoints (send an ARP request packet). The endpoints would then reply with a Gratuitous ARP packet. These packets inform the IMG that the endpoints are still ‘alive’. If the IMG sends out an ARP Request Packet and does not receive a Gratuitous ARP in return it will continue to send ARP Requests until the pre-configured number of requests is met. If at that time no Gratuitous ARP’s are sent back then the IMG will initiate a 'switchover’ to its ‘Hot Standby’ Port (Data 1 in this case). If the switchover solves the problem, then the IMG will continue processing calls on the new ‘switched-over’ port. However, if the issue is not solved, the IMG would continue to switch back and forth between Data 0 and Data 1 (ping pong effect) until the issue in the network is solved. The feature is enabled through ClientView and can be enabled on any of the network interfaces (CTRL, DATA, SIGNALING) located on the rear of the IMG.

If multiple endpoints are configured, the switchover will not occur unless ALL endpoints fail to respond to the ARP.

The second part of this feature allows the customer to initiate a link switchover manually. A manual switchover can be executed from the Logical Interface object within ClientView. The manual switchover was added to allow the customer the ability to switch from one network to another. An Event such as maintenance to a specific network is now possible by switching away from the network that needs maintenance to a different network that could handle any traffic while maintenance is being performed.

Below is diagram displaying the Smart-Probing Via Ethernet Redundancy feature using ports Data 0 and Data 1.

Diagram:

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Configuration:

The procedure below displays the steps involved in configuring the Ethernet Redundancy Via Smart-Probe feature. The procedure uses Data 0 and Data 1 as the interfaces used for the Ethernet Redundancy Feature. Data 0 will be the active port and Data 1 will be configured as the Hot Standby (Link is 'Up' but Tx/Rx are disabled).

• Create a Logical IMG object. See IMG 1010 - Logical IMG for more information.

• Create a Physical IMG object. See IMG 1010 - Physical IMG for more information.

• Right Click on ‘IMG Name:’ and select New Network. A network pane will appear. No configuration needs to be accomplished here. This object will allow for multiple IP objects to get created below it. See IMG 1010 - IP Network (Interface) for more information.

• Right Click on IP Network and select New Logical Interface. The following ClientView Object Pane will appear. Configure the Data interface. See IMG 1010 - Logical Interface for more information.
  
  

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  • Interface- In this example Data was selected from drop down menu.

  • Probe Detection (Default = Disabled)- To enable Smart Probing feature on the DATA 0/1 select Enabled from drop down list.

  • Probe Interval – Select from drop down menu number of seconds.

  • Probe Threshold – Select from drop down menu number ARP requests IMG will send before initiating a switchover from interface Data 0 to Data 1

• Right Click on Logical Interface and select New Probe Endpoint. In the object pane that appears, click in the IP address field and enter the IP address of the endpoint that the IMG will sent ARP request packets to. Up to three separate endpoints can be configured. See IMG 1010 - Probe Endpoint for more information.

• To give the Data Port an IP address, right click on IP Network again and select New IP Address. See IMG 1010 - IP Address for more information.
  
  

  • Physical Interface – Select ‘CPU’ from drop down menu.

  • Logical Interface – Select the interface that the Ethernet Link Redundancy Via Smart Probe will be configured on. In this example, Data was selected.

  • Address Type – IMG supports IPV4 only.

  • IP Address- IP address that will be assigned to this port. Click in the IP address field and enter IP address in box that appears.

  • Subnet Mask (Default 255.255.255.0)- Enter subnet mask. Click in the Subnet field and enter IP address in box that appears.

  • Default Gateway – IP address of the Default Gateway this interface will connect to.

  • Gratuitous ARP and ARP Responses – Leave as enabled
     

Additional Information:

• Ethernet Redundancy via Smart Probing is configurable on all three network interfaces located on rear of IMG. (Ctrl 0/1, Data 0/1 and Signaling 0/1)

• Up to three Probe Endpoints can be added to each interface. (Ctrl, Data, Sig)

• A probe packet is not confined to any one subnet. As long as there is a valid IP address, the IMG can send a probe message to it.

• A probe message is an ARP request.

• If Hardware address is known for an endpoint then a unicast ARP packet rather than a broadcast packet will be sent.

• The receipt of a Gratuitous ARP from an endpoint will cause the cached HW address to be updated.

• A switchover will generate gratuitous ARPs over the newly active port.

• A switchover will flush the Hardware address of each endpoint from the ARP Cache.

• A switchover will reset the missed probe count.

• Changing configuration information will result in probe logic being reset. Any missed probe counts will be reset.

• Minimum interval at which probe packets can be sent is 1 second.

• Minimum time between switch-overs is 10 seconds.