Cisco – How to View ARP Timeout Setting on Cisco Router?

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What command do you use to view the ARP Timeout setting on a Cisco Router?

Not the remaining time or ageing time on a particular ARP entry. But the actual timeout setting itself. I know it is by default 4 hours, I just need to know what show command shows this.

Some searches online pointed me towards show arp timeout or show ip arp timeout but neither of these worked on the GNS3 Routers I tried it against. It may only be available on real Routers, in which case I would love to have that confirmed. (And for someone to post the output of the command from a real router).

Best Answer

Sigh, rookie mistake. The command arp timeout is available in interface configuration mode only, and is set specific to each interface. You can view the setting in show interface:

router1#  conf t
Enter configuration commands, one per line.  End with CNTL/Z.
router1(config)# arp timeout 99999
                     ^
% Invalid input detected at '^' marker.

router1(config)# int eth0/1
router1(config-if)# arp timeout 99999
router1(config-if)# end
*Jan 11 17:37:56.285: %SYS-5-CONFIG_I: Configured from console by console
router1# show int eth0/1 | i Timeout
  ARP type: ARPA, ARP Timeout 1d03h
router1# show int eth0/1
Ethernet0/1 is administratively down, line protocol is down
  Hardware is AmdP2, address is aabb.cc00.0110 (bia aabb.cc00.0110)
  MTU 1500 bytes, BW 10000 Kbit/sec, DLY 1000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  ARP type: ARPA, ARP Timeout 1d03h
  Last input never, output never, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     ...
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