Understanding ICMP Fragment Protection

Internet Control Message Protocol (ICMP) provides error reporting and network probe capabilities. Because ICMP packets contain very short messages, there is no legitimate reason for ICMP packets to be fragmented. If an ICMP packet is so large that it must be fragmented, something is amiss.

When you enable the ICMP fragment protection screen option, Junos OS blocks any ICMP packet that has the More Fragments flag set or that has an offset value indicated in the offset field. See Figure 66.

Related Topics

• Junos OS Feature Support Reference for SRX Series and J Series Devices