Setting The Mac Address Aging Timer; Configuring A Broadcast Suppression Ratio On The Ethernet Port - 3Com 3C13636 Configuration Manual

3Com Router 3000 Ethernet Family
Configuration Guide

3.2.8 Setting the MAC Address Aging Timer

An appropriately configured aging timer can effectively implement the function of MAC
address aging.
An inappropriate aging timer, however, either too long or too short, may cause the
router to broadcast packets with unknown destination MAC addresses, degrading the
performance. If the aging time is too long, the MAC address table on the router may
become filled up with out-of-date entries, failing to accommodate to the changes on the
network. If the aging time is too short, the router may delete valid entries.
Normally, you are recommended to use the default MAC address aging time, that is,
300 seconds.
Perform the following configuration in Ethernet port view.
Table 3-8 Set the MAC address aging timer
Set the MAC address aging time
Restore the default MAC address aging
timer setting.
The default MAC address aging timer is set to 300 seconds.

3.2.9 Configuring a Broadcast Suppression Ratio on the Ethernet Port

To suppress broadcast storms and avoid congestion, you may configure the permitted
broadcast traffic size on a port. Once broadcast traffic exceeds the specified value, the
system starts discarding broadcast packets until the broadcast traffic decreases to the
acceptable degree.
In the broadcast-suppression pct command, how much broadcast traffic can pass
through depends on the specified maximum wire speed ratio of the broadcast traffic on
the port. As this ratio is decreasing, the permitted broadcast traffic size decreases.
When the ratio is set to 100, all broadcast traffic can pass through without suppression.
Perform the following configuration in Ethernet port view.
Table 3-9 Configure a broadcast suppression ratio on the Ethernet port
Configure a broadcast suppression ratio
on the Ethernet port
Restore
suppression ratio on the Ethernet port
Operation
Operation
the default broadcast
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3-6
Chapter 3 Layer 2 Ethernet Port Configuration
Command
mac-address timer aging {age-time |
no-age}
undo mac-address timer aging
Command
broadcast-suppression pct
undo broadcast-suppression