ipsec global-df-bit
Use ipsec global-df-bit to configure the DF bit for the outer IP header of IPsec packets on all interfaces.
Use undo ipsec global-df-bit to restore the default.
Syntax
ipsec global-df-bit { clear | copy | set }
undo ipsec global-df-bit
Default
The DF bit setting of the original IP header is copied to the outer IP header for IPsec packets.
Views
System view
Predefined user roles
network-admin
mdc-admin
Parameters
clear: Clears the DF bit in the outer IP header. IPsec packets can be fragmented.
copy: Copies the DF bit setting of the original IP header to the outer IP header.
set: Sets the DF bit in the outer IP header. IPsec packets cannot be fragmented.
Usage guidelines
This command is effective only when the IPsec encapsulation mode is tunnel mode. It is not effective in transport mode because the outer IP header is not added in transport mode.
This command does not change the DF bit for the original IP header of IPsec packets.
Packet fragmentation and reassembly might cause packet forwarding to be delayed. You can set the DF bit to avoid the forwarding delay. However, to prevent IPsec packets from being discarded, you must make sure the path MTU is larger than the IPsec packet size. As a best practice, clear the DF bit if you cannot make sure the path MTU is larger than the IPsec packet size.
Examples
# Set the DF bit in the outer IP header of IPsec packets on all interfaces.
<Sysname> system-view [Sysname] ipsec global-df-bit set
Related commands
ipsec df-bit