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ARP issue

enlightenedinc
enlightenedinc used Ask the Experts™
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Hello,

We are having a issues with multiple devices on our network not being able to connect to the Internet but can get to network shared, deivices, etc. It started with two servers have issues and now we have random desktops, laptops, servers, and even WAP's having Internet issues.

When a computer cannot get out to the internet we check the ARP cache by going to cmd prompt arp -a and notice that the firewall is either not listed or says invalid.  When we manually enter the ARP entry for the firewall internet is restored immediately.

SonicWall Pro 3060 firewalls (two- both have ARP issues one more than the other, DHCP and VPN on firewall)
D-link- switch- had collisions on one port
two netgear and a linksys.

One company recommended that the switch be replaced. We replaced the switch with a brand new HP switch, plugged both firewalls and all servers and switches directly into the new switch and still had the ARP issue. See attachment for further troubleshooting we have done.  

SonicWall technical support recommended we upgrade the firmware on the firewall because it may be causing the issue. Any other input would be greatly appreciated.






ARP-issues-troubleshooting-exper.docx
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I have seen arp issues when the aging time for arps on the router or L3 switch is not in sync with the mac aging time for the L2 function on the switch.

Another arp issue can occur when DHCP is handing out addresses at a faster rate than the ageout time on the router when many devices are sharing a relatively smaller pool of addresses like wireless environments.
Top Expert 2010

Commented:
You said you have two firewall appliances.  I recognize the sonicwall as one, but what's the other?  What if you started with JUST the sonicwall, the hp switch and the hosts.  Leave off all the other network gear.  what happens then?  how long before you start having ARP issues?

Author

Commented:
Both are SonicWall Pro 3060. When the issues first starting rebooting the firewall could bring the Internet back up on the devices for about 3 hours. This time rebooting firewall did not work.  

We tried it with the SonicWall 1 (allied is the ISP), HP switch and a laptop. No Internet on the laptop.

We then plugged in SonicWall 2 (Covad is the ISP), SonicWall 1 (allied), HP, and Laptop and got Internet on the laptop.

Unplugged sonicWall 2 (covad), (leaving SonicWall 1, HP and laptop only) and still had Internet.
Top Expert 2010
Commented:
ok...i'd try updating the sonicwalls.

Author

Commented:
thanks thats the next move.
Top Expert 2010

Commented:
Let us know if that resolves the issue ultimately and thanks for the points!

Author

Commented:
So far so good. No VPN or ARP issues for almost two weeks.
Top Expert 2010

Commented:
that's great...glad to hear it!