Chapter 23 Configuring Dynamic ARP Inspection

Configuring Dynamic ARP Inspection

If the log buffer overflows, it means that a log event does not fit into the log buffer, and the display for the show ip arp inspection log privileged EXEC command is affected. A -- in the display appears in place of all data except the packet count and the time. No other statistics are provided for the entry. If you see this entry in the display, increase the number of entries in the log buffer or increase the logging rate.

The log buffer configuration applies to each stack member in a switch stack. Each stack member has the specified logs number entries and generates system messages at the configured rate. For example, if the interval (rate) is one entry per second, up to five system messages are generated per second in a five-member switch stack.

Beginning in privileged EXEC mode, follow these steps to configure the log buffer. This procedure is optional.

 

Command

Purpose

 

 

 

Step 1 configure terminal

Enter global configuration mode.

 

 

 

Step 2 ip arp inspection log-buffer {entries

Configure the dynamic ARP inspection logging buffer.

 

number logs number interval

By default, when dynamic ARP inspection is enabled, denied or dropped

 

seconds}

 

ARP packets are logged. The number of log entries is 32. The number of

 

 

 

 

system messages is limited to 5 per second. The logging-rate interval is 1

 

 

second.

 

 

The keywords have these meanings:

 

 

For entries number, specify the number of entries to be logged in the

 

 

buffer. The range is 0 to 1024.

 

 

For logs number interval seconds, specify the number of entries to

 

 

generate system messages in the specified interval.

 

 

For logs number, the range is 0 to 1024. A 0 value means that the entry

 

 

is placed in the log buffer, but a system message is not generated.

 

 

For interval seconds, the range is 0 to 86400 seconds (1 day). A 0 value

 

 

means that a system message is immediately generated (and the log

 

 

buffer is always empty).

 

 

An interval setting of 0 overrides a log setting of 0.

 

 

The logs and interval settings interact. If the logs number X is greater than

 

 

interval seconds Y, X divided by Y (X/Y) system messages are sent every

 

 

second. Otherwise, one system message is sent every Y divided by X (Y/X)

 

 

seconds.

 

 

 

 

 

Catalyst 3750-E and 3560-E Switch Software Configuration Guide

 

 

 

 

 

 

OL-9775-02

 

 

23-13

 

 

 

 

 

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Cisco Systems 3750E manual Ip arp inspection log-buffer entries, Number logs number interval, 23-13