Kernel Slabs Overview:

The slab allocator in the Linux kernel is used for efficient memory management. It groups objects of the same type into caches, which are divided into slabs.

Each slab contains multiple objects and helps to minimize fragmentation and enhance memory allocation efficiency.

Interpreting the Exhibit:

The exhibit shows output related to various kernel slab caches.

The line forip6_sessionindicates that there are 1300 kB allocated for this slab, which means the total memory size allocated for IPv6 session objects in the kernel is 1300 kB.

References:

Fortinet Community: Explanation of kernel slab allocation and usage​(Welcome to the Fortinet Community!)​​(Hammertux)​.

Linux Kernel Documentation: Slab Allocator details​(Hammertux)​.

The session table entry provided shows detailed information about a specific network session passing through the FortiGate device. From the session details, we can see that the session has various attributes such as state, protocol, policy, and inspection details.

The session state (proto_state=11) indicates that the session is being actively processed and inspected.

Thenpd_state=00000000suggests that the session is being handled by the CPU rather than offloaded to a Network Processor (NP).

The session is marked for security profile inspection, evident from the detailed byte/packet counts and other session parameters.

From these indicators, it's clear that FortiGate is using its CPU to perform security profile inspection on this session rather than simply forwarding the traffic without inspection or relying solely on IPS inspection.

References

Fortinet Documentation on Session Table

Fortinet Community Discussion on Session Table

Soft Reset of BGP:

Performing a soft reset of BGP is a common method to resolve issues where prefixes are not being received. It forces both BGP peers to resend their complete routing tables to each other.

This can be done using the command:execute router clear bgp soft inandexecute router clear bgp soft out.

Network Import Check:

Thenetwork-import-checkcommand controls whether the FortiGate should verify that the prefix exists in the routing table before advertising it.

Disabling this check can resolve issues where valid prefixes are not advertised due to stringent verification.

The command to disable this is:config router bgp set network-import-check disable end.

BGP Configuration Verification:

Ensure that the BGP configuration on FGT-B is correctly set to advertise the network 172.16.54.0/24.

Verify that the network statement is correctly configured and matches the intended prefix.

References:

Fortinet Community: Technical Note on Configuring BGP​(Welcome to the Fortinet Community!)​.

Fortinet Documentation: Configuring BGP on FortiGate​(Fortinet Document Library)​.