When using ICMP, echo requests and replies should be differentiated from error messages. For the error messages, ICMP redirect will require and additional inspection.
- An ICMP echo request directed to the virtual router's address may only be answered by the LANCOM router when it is the master.
- ICMP redirects may also be sent from virtual routers but the address of the router to which the packet was sent must be entered as the sender address. This is to be determined from the packet's target MAC address.
- If the LANCOM router is addressed via its physical MAC address and the target of the packet is linked to a virtual router, the address of which is connected to the receiving interface, then an ICMP redirect is returned and the sender receives the address of the virtual router.
- For all other error messages, it does not matter whether the virtual router's address or the real address is used as the sender address. To simplify matters, the real address is always used.
Note: With the implementation of VRRP in LCOS, the previous option 'local routing' in the IP Router menu has been replaced with 'Send ICMP redirects'. If this option is enabled, ICMP redirects are sent, if the option is disabled, the packets are always forwarded.
