Overview of Blackhole routes
Networking switches drop the received packet destined for blackhole routes without logging any packet
information. Information like source IP, destination IP, VlanID and Port ID of the packets destined for the
configured static blackhole routes is logged with this feature.
A static blackhole route is a route manually configured, on a switch, to drop packets destined for a particular
network/IP address as it can be configured to a host as well as to a network. The user is able to set up the
dropping of particular packets destined for a given IP address by enabling or disabling the route. Since all the
packets received on the blackhole route are being logged, there is a performance impact and the exact
performance numbers will be evaluated.
A new debug type is also introduced with this feature to log blackhole debug messages.
Commands
ip route
Within the config context:
Syntax
ip route
<IP-ADDR/MASK-LENGTH>
blackhole logging
ipv6 route
<IPV6-ADDR/MASK-LENGTH>
blackhole logging
Description
Configures the debug logging for a static blackhole route for either IPv4 or IPv6.
Options
logging
Allows the packets received on the blackhole route to be logged. When logging is enabled on the switch for
blackhole routes, the debug logs are sent to the configured destination. The destination can be a logging
server, a buffer, or even the switch itself.
Usage
[no] ip route
<IP-ADDR/MASK-LENGTH>
blackhole
[no] ipv6 route
<IP-ADDR/MASK-LENGTH>
blackhole
Disables the logging facility for the configured blackhole routes.
The
[no]
form of the command does not have the logging option.
Debug Logs
The following debug message will be logged after a blackhole route logging is enabled.
Packet destined blackhole route with Source Ip =<IP ADDRESS>,
Destination IP=<DESTINATION IP>, VLAN Interface = <VLAN INTERFACE>, Lport = <PORT ID>
Chapter 7
Log violation of Blackhole route
Chapter 7 Log violation of Blackhole route
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