It has been observed on the TCNJ network that the Mac OS X 10.9 (Mavericks) unicast ARP cache bug appears.
The original Apple discussion forum thread can be found at https://discussions.apple.com/thread/5483424.
This bug causes your network connection to stop working for a few seconds at fixed intervals (usually 30 or 60 seconds). This may be observed while using applications such as Facetime or other video streaming applications that may momentarily pause during your session.
This issue affects Macs running OS X 10.9 while using the internal gigabit Ethernet adapter or internal wireless. If you are using an external USB 100Mbps Ethernet adapter, the problem may not occur. To verify you are having this issue, run the “ping” command to see if you get 4-5 “Request timeout” messages at regular intervals.
Open a Terminal (located in the Applications folder > Utilities folder) and type the following command:
testmac:~ testuser$:~ testuser$ ping beast.tcnj.edu PING beauty.tcnj.edu (18.104.22.168): 56 data bytes 64 bytes from 22.214.171.124: icmp_seq=0 ttl=63 time=1.026 ms 64 bytes from 126.96.36.199: icmp_seq=1 ttl=63 time=3.680 ms 64 bytes from 188.8.131.52: icmp_seq=2 ttl=63 time=1.308 ms (...) 64 bytes from 184.108.40.206: icmp_seq=37 ttl=63 time=1.443 ms 64 bytes from 220.127.116.11: icmp_seq=38 ttl=63 time=1.397 ms 64 bytes from 18.104.22.168: icmp_seq=39 ttl=63 time=5.447 ms Request timeout for icmp_seq 40 Request timeout for icmp_seq 41 Request timeout for icmp_seq 42 Request timeout for icmp_seq 43 Request timeout for icmp_seq 44 64 bytes from 22.214.171.124: icmp_seq=45 ttl=63 time=2.347 ms 64 bytes from 126.96.36.199: icmp_seq=46 ttl=63 time=1.330 ms 64 bytes from 188.8.131.52: icmp_seq=47 ttl=63 time=1.690 ms (...) 64 bytes from 184.108.40.206: icmp_seq=54 ttl=63 time=1.321 ms 64 bytes from 220.127.116.11: icmp_seq=55 ttl=63 time=1.387 ms 64 bytes from 18.104.22.168: icmp_seq=56 ttl=63 time=1.573 ms ^C --- beauty.tcnj.edu ping statistics --- 57 packets transmitted, 52 packets received, 8.8% packet loss round-trip min/avg/max/stddev = 1.026/2.498/5.447/1.323 ms testmac:~ testuser$
Once you verify that you are seeing the bug, perform the following commands below to apply a temporary fix by disabling the unicast ARP function.
Type the following two lines. The first one may give you an error message if the /etc/sysctl.conf file doesn’t already exist. This is okay.
sudo cp /etc/sysctl.conf /etc/sysctl.conf.bak echo "net.link.ether.inet.arp_unicast_lim=0" | sudo tee -a /etc/sysctl.conf
Reboot your Mac and re-run the “ping” command test. You should no longer see the “Request timeout” messages appearing regularly.
NOTE: This bug appears to be fixed in Mac OS X 10.10 (Yosemite), however Yosemite has other known wireless bugs separate from this issue which will require fixes from Apple.