icmp blackhole unreachable send
Function
The icmp blackhole unreachable send command enables the BRAS to send a Destination Unreachable ICMP packet to an initiator when a tracert packet matches an IPv4 blackhole route.
The undo icmp blackhole unreachable send command disables the BRAS from sending a Destination Unreachable ICMP packet to an initiator when a tracert packet matches an IPv4 blackhole route.
By default, the BRAS is disabled from sending a Destination Unreachable ICMP packet to an initiator when a tracert packet matches an IPv4 blackhole route.
Usage Guidelines
Usage Scenario
If static IPv4 blackhole routes are configured on the BRAS and a user goes offline, only the IPv4 blackhole route corresponding to the user's address segment exists on the BRAS. When a tracert packet matches the IPv4 blackhole route, the BRAS discards the packet. As a result, an initiator cannot detect that the user has gone offline.
After you run the icmp blackhole unreachable send command, the BRAS sends a Destination Unreachable ICMP packet to an initiator, notifying the initiator that the user has gone offline if a user goes offline and a tracert packet matches the IPv4 blackhole route.
Pre-configuration Tasks
Static IPv4 blackhole routes have been configured on the BRAS.
