Do problems occur in route calculation when the backbone area is discontinuous

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If the backbone area is discontinuous, the networks in some areas may be unreachable and routing loops may occur in inter-area routes and external routes.

Other related questions:
Can an S series switch correctly calculate routes when OSPF backbone areas are not continuous
For S series switches supporting OSPF, if OSPF backbone areas are not continuous, some areas may be unreachable and loops may occur on inter-area and external routes.

Why are the routes with smaller costs passing through the backbone area not preferred
OSPF defined by RFC 2328 must be backward compatible with RFC 1583. As specified in RFC 2328, if "RFC1583 Compatibility" is disabled, when routes can be learnt through common areas and the backbone area, the routes learnt through common areas are preferred regardless of their costs. This is to reduce the burden on the backbone area.

Problem and solution when disk isolation occurs
You can perform the following operations when disk isolation occurs: The following causes may result in disk isolation: Bit error Reinserting disks repeatedly Disk power connection problem 1. Bit error Check the bit error of back-end SAS disks. Search keywords err inc and disable disk phy in the SES log. Note: phy:9 phymon***disable disk phy in the log shows that disk phy 9 is isolated. That is, the disk in slot 9 is isolated (phy0 to phy23 corresponds to disk 0 to 23). Troubleshooting 1. Before removing a faulty disk, collect S.M.A.R.T. information. 2. If conditions permit, insert the isolated disk to other slots to check whether isolation is caused by the disk or the slot. If isolation is caused by the disk, apply for disk replacement. If isolation is caused by the slot, check whether the slot has any foreign objects. Check the bit error on Fibre Channel disks. Search keyword lcv that is Fibre Channel bit errors in the SES log. If HD 0 and lcv ffff are displayed, the information indicates that a large quantity of bit errors are produced in slot 0 and cause disk isolation. The back-end Fibre Channel bit errors can spread from the port to the disk. If a Fibre Channel disk is isolated, check whether bit errors occur on the port by using the following methods: Check on the ISM. Enter fc allinfo in MML mode. Note: If any information displayed is not 0, bit errors exist. If bit errors are detected on the port, verify whether bit error are generated in the link. For details about how to verify, see the troubleshooting cases for a single link failure of the Fibre Channel enclosure disk caused by bit errors. Troubleshooting: If only one disk fails, verify the failure by using the above method. If a link fails, replace the optical module and optical cables and verify the failure. If a link does not fail, use the same method as one carried out on the SAS disk. If multiple disks are faulty, refer to the troubleshooting cases for a single link failure of the Fibre Channel enclosure disk caused by bit errors. 2. Reinserting disks repeatedly Note: A drive can isolate the disk from other ones if intermittent disconnections occur on the disk. Reinserting disks repeatedly may lead to disk isolation. Verify whether the disk is reinserted many times within a short period. If such a case exists, reinserting disk may result in disk isolation. Troubleshooting: Reinsert the disk. 3. Disk power connection problem Note: If the disk enclosure is affected by violent shaking, disk power may be insecurely connected and the disk is isolated. Troubleshooting: Contact R&D engineers for further analysis.

Why OSPF on an S series switch does not preferentially select a route with a small cost value and through the backbone area
OSPF defined by RFC 2328 must be compatible with RFC 1583. As defined in RFC 2328, if "RFC1583 Compatibility" is disabled, the routes learned through common areas are preferred regardless of their costs when routes can be learned through common areas and the backbone area. This helps reduce the burden of the backbone area.

Problem and solution when active/standby switchover frequently occurs
Check the service interface status first. If the service interface repeatedly switches between Down and Up, repeated hot standby switchover is triggered. If the service interface is normal, it is usually because the intervals for sending heartbeat packets on the two firewalls are different. Modify them so that they are the same.

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