3D Innovations 3.0.1 appendix Select the required setting for the DF bit

Appendix B Site-to-Site VPN User Interface Reference

Site to Site VPN Policies

Table B-18	VPN Global Settings Page > General Settings Tab (continued)
Element		Description
DF Bit		Supported on Cisco IOS routers, Catalyst 6500/7600 devices,
		PIX 7.0 and ASA devices.
		A Don't Fragment (DF) bit within an IP header determines whether
		a device is allowed to fragment a packet. For more information, see
		Understanding Fragmentation, page 9-72.
		Select the required setting for the DF bit:
		• Copy—To copy the DF bit from the encapsulated header in the
		current packet to all the device’s packets. If the packet’s DF bit
		is set to fragment, all future packets will be fragmented. This is
		the default option.
		• Set—To set the DF bit in the packet you are sending. A large
		packet that exceeds the MTU will be dropped and an ICMP
		message sent to the packet’s initiator.
		• Clear—If you want the device to fragment packets regardless
		of the original DF bit setting. If ICMP is blocked, MTU
		discovery will fail and packets will only be fragmented after
		encryption.
Enable Fragmentation Before		Supported on Cisco IOS routers, Catalyst 6500/7600 devices,
Encryption		PIX 7.0 and ASA devices.
		When selected, enables fragmentation to occur before encryption, if
		the expected packet size exceeds the MTU.
		Lookahead Fragmentation (LAF) is used before encryption takes
		place to calculate the packet size that would result after encryption,
		depending on the transform sets configured on the IPSec SA. If the
		packet size exceeds the specified MTU, the packet will be
		fragmented before encryption.
Enable Notification on		Supported on PIX 7.0 and ASA devices.
Disconnection		When selected, enables the device to notify qualified peers of
		sessions that are about to be disconnected. The peer receiving the
		alert decodes the reason and displays it in the event log or in a
		pop-up panel. This feature is disabled by default.
	User Guide for Cisco Security Manager 3.0.1
B-52		OL-8214-02