Monitoring And Maintaining Unicast Rpf - Cisco Catalyst 4500 Series Configuration Manual

Chapter 34 Configuring Unicast Reverse Path Forwarding

Monitoring and Maintaining Unicast RPF

To monitor and maintain Unicast RFP, perform this task:
Command
Switch# show ip traffic
Switch(config-if)# no ip verify unicast
Unicast RPF counts the number of packets dropped or suppressed because of malformed or forged source
addresses. Unicast RPF counts dropped or forwarded packets that include the following global and
per-interface information:
•
•
•
The show ip traffic command shows the total number (global count) of dropped or suppressed packets
as dropped by software; it does not include the count of packets dropped by hardware. The Unicast RPF
drop count is included in the IP statistics section.
Switch# show ip traffic
IP statistics:
Rcvd:
Opts:
Frags: 0 reassembled, 0 timeouts, 0 couldn't reassemble
Bcast: 205233 received, 0 sent
Mcast: 463292 received, 462118 sent
Sent:
! The second line below ("0 unicast RPF") displays Unicast RPF packet dropping
information.
Drop:
A nonzero value for the count of dropped or suppressed packets can mean one of two things:
•
•
The show ip interface command shows the total of dropped or suppressed packets at a specific interface.
If Unicast RPF is configured to use a specific ACL, that ACL information is displayed along with the
drop statistics.
Switch> show ip interface fast 2/1
Unicast RPF ACL 197
1 unicast RPF drop
1 unicast RPF suppressed drop
OL-25340-01
Global Unicast RPF drops
Per-interface Unicast RPF drops
Per-interface Unicast RPF suppressed drops
1471590 total, 887368 local destination
0 format errors, 0 checksum errors, 301274 bad hop count
0 unknown protocol, 0 not a gateway
0 security failures, 0 bad options, 0 with options
0 end, 0 nop, 0 basic security, 0 loose source route
0 timestamp, 0 extended security, 0 record route
0 stream ID, 0 strict source route, 0 alert, 0 other
0 fragmented, 0 couldn't fragment
990158 generated, 282938 forwarded
3 encapsulation failed, 0 unresolved, 0 no adjacency
0 no route, 0 unicast RPF, 0 forced drop
Unicast RPF is dropping or suppressing packets that have a bad source address (normal operation).
Unicast RPF is dropping or suppressing legitimate packets because the route is misconfigured to use
Unicast RPF in environments where asymmetric routing exists; that is, where multiple paths can
exist as the best return path for a source address.
Purpose
Displays global switch statistics about Unicast RPF drops
and suppressed drops.
Disables Unicast RPF at the interface.
Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
Monitoring and Maintaining Unicast RPF
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