3D Innovations 3.0.1 appendix For more information, see Understanding Fragmentation

Appendix B Site-to-Site VPN User Interface Reference

Site to Site VPN Policies

Field Reference

Table B-18 VPN Global Settings Page > General Settings Tab

Element

Description

Fragmentation Settings

Fragmentation Mode	Supported on Cisco IOS routers and Catalyst 6500/7600 devices.
	Fragmentation minimizes packet loss in a VPN tunnel when
	transmitted over a physical interface that cannot support the original
	size of the packet.
	Select the required fragmentation mode option from the list:
	• No Fragmentation - Select if you do not want to fragment prior
	to IPSec encapsulation. After encapsulation, the device
	fragments packets that exceed the MTU setting before
	transmitting them through the public interface.
	• End to End MTU Discovery - Select to use ICMP messages for
	the discovery of MTU. Use this option when the selected
	technology is IPSec.
	End-to-end MTU discovery uses Internet Control Message
	Protocol (ICMP) messages to determine the maximum MTU
	that a host can use to send a packet through the VPN tunnel
	without causing fragmentation.
	• Local MTU Handling - Select to set the MTU locally on the
	devices. This option is typically used when ICMP is blocked,
	and when the selected technology is GRE.
	For more information, see Understanding Fragmentation,
	page 9-72.
Local MTU Size	Supported on Cisco IOS routers and Catalyst 6500/7600 devices,
	when Local MTU Handling is the selected fragmentation mode
	option.
	The MTU size can be between 540 and 1500 bytes.

	User Guide for Cisco Security Manager 3.0.1
OL-8214-02		B-51