To verify that jumbo frames are correctly configured end-to-end for an iSCSI workload, a test packet must be sent that is larger than the standard 1500-byte MTU but small enough to fit within the jumbo frame MTU (typically 9000 bytes). The test must also prevent the packet from being fragmented.

The command ping -disallow-fragmentation true -packet-size 8900 achieves this. The -disallow-fragmentation true option sets the "Don't Fragment" (DF) bit in the IP header. The -packet-size 8900 specifies an ICMP payload of 8900 bytes. The total IP packet size will be 8928 bytes (8900 payload + 20 IP header + 8 ICMP header), which is a valid jumbo frame that fits within a 9000-byte MTU. A successful reply confirms the path is correctly configured.

A. This command allows fragmentation and uses a standard packet size, which fails to test the path's ability to handle unfragmented jumbo frames.

B. The specified packet payload of 9000 bytes, plus IP/ICMP headers (28 bytes), creates a total packet size of 9028 bytes, which exceeds the 9000-byte MTU and will fail even on a correctly configured path.

D. This command tests with a standard 1500-byte packet, which only verifies standard network connectivity, not the correct configuration of jumbo frames.

1. NetApp Knowledge Base

Article 1030213

"How to test for jumbo frames with ping": This article explicitly states

"To test for jumbo frames

use the ping command with the -packet-size option set to a value less than the MTU

and the -disallow-fragmentation option set to true." It provides a specific example using a packet size of 8972 for a 9000 MTU

which aligns with the logic for selecting option C.

2. NetApp Technical Report TR-4336

"iSCSI Configuration and Implementation Guide for Clustered Data ONTAP": In the "Jumbo Frames" section (page 17)

this guide recommends verifying jumbo frame configuration using the ping command with a large packet size (e.g.

8972) and with fragmentation disallowed. This confirms that the test packet size must be less than the 9000-byte MTU.

3. ONTAP 9 Commands

Manual Page Reference for ping: The documentation for the ping command details the -packet-size parameter

which specifies the number of data bytes in the ICMP packet

and the -disallow-fragmentation {true|false} parameter

which controls the DF bit. This confirms the command structure and the function of the options used in the correct answer.