Figure 46. Example of ICMP Redirect
To see routing changes due to ICMP redirect messages, select NETSTAT menu 2 or NETSTAT *RTE and then press PF11. Comparing the next hop in this display with the next hop present in the routing table, you can verify whether a route has been dynamically changed.
Dead Gateway Processing
Two types of gateway failures can occur:
vFailure of a
vFailure of a gateway other than the
Dead gateway processing is initiated when IP receives a negative advice indicator from either TCP or the data link layer. These indicators from TCP and the data link layer are referred to as advice since they may result from transient conditions as well as from a serious gateway failure.
Negative Advice from TCP or the Data Link Layer
Retransmissions on a TCP connection occur as a result of transient or
Chapter 2. TCP/IP: Operation, Management, and Advanced Topics 55