Junos® OS Ethernet Interfaces Configuration ... - Juniper Networks

Adjusting the ARP Aging Timer
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Documentation
• Junos® OS Ethernet Interfaces
By default, the ARP aging timer is set at 20 minutes. In environments with many directly
attached hosts, such as metro Ethernet environments, increasing the amount of time
between ARP updates by configuring the ARP aging timer can improve performance in
an event where having thousands of clients time out at the same time might impact
packet forwarding performance. In environments where there are devices connected
with lower ARP aging timers (less than 20 minutes), decreasing the ARP aging timer can
improve performance by preventing the flooding of traffic toward next hops with expired
ARP entries. In most environments, the default ARP aging timer value does not need to
be adjusted.
To configure the system-wide ARP aging timer, include the aging-timer statement at the
[edit system arp] hierarchy level:
[edit system arp]
aging-timer minutes;
The aging timer range is from 1 through 240 minutes. The timer value you configure takes
effect as ARP entries expire. In other words, each subsequent refreshed ARP entry receives
the new timer value. The new timer value does not apply to ARP entries that exist at the
time you commit the configuration.
For more information about statements you can configure at the [edit system] hierarchy
level, see the Junos OS System Basics Configuration Guide.
•
arp (System)
• Ethernet Interfaces Overview on page 35
• Junos® OS Ethernet Interfaces
Configuring the Interface Speed on Ethernet Interfaces
Copyright © 2012, Juniper Networks, Inc.
For M Series and T Series Fast Ethernet 12-port and 48-port PIC interfaces, the
management Ethernet interface (fxp0 or em0), the J Series Gigabit Ethernet uPIM
interfaces, and the MX Series Tri-Rate Ethernet copper interfaces, you can explicitly set
the interface speed. The Fast Ethernet, fxp0, and em0 interfaces can be configured for
10 Mbps or 100 Mbps (10m | 100m). The J Series Gigabit Ethernet uPIM interfaces and
the MX Series Tri-Rate Ethernet copper interfaces can be configured for 10 Mbps,
100 Mbps, or 1 Gbps (10m | 100m | 1g). MX Series routers, with MX-DPC and Tri-Rate
Copper SFPs, support 20x1 Copper to provide backwards compatibility with 100/10BASE-T
and 1000BASE-T operation through an Serial Gigabit Media Independent Interface
(SGMII) interface.
Chapter 2: Configuring Ethernet Interfaces
49