Series 1800 router after power failure

Unanswered Question
Aug 24th, 2009
User Badges:

We are using a Series 1800 router to connect to the Internet and provide Wireless connections. We are also using a Linksys router to connect a server and client to the same Series 1800 router. Whenever we lose power, the Series 1800 will no longer allow the Linksys to connect to the Internet. If we swap out the Linksys with another router, it will work fine. What is causing the Series 1800 to stop allowing a connection like this?

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
pompeychimes Mon, 08/24/2009 - 19:32
User Badges:
  • Bronze, 100 points or more

Is the Linksys truely acting as a Router or is it just an AP? I assume you are using DHCP on your network. What device is acting as you DHCP Server?

Richard Burts Tue, 08/25/2009 - 03:58
User Badges:
  • Super Silver, 17500 points or more
  • Hall of Fame,

    Founding Member

  • Cisco Designated VIP,

    2017 LAN, WAN


We do not have enough information to be able to suggest the cause of the problem. Can you give us some detail of how things are connected? Can you provide the config of the router? Am I correct in understanding that everything works except the Linksys? Your description sounds like the problem has happened several times. So if there is a power outage and the router is not letting the Linksys connect, is there something that you do to get the Linksys connected and working?

If we knew these things we might be able to give you better answers.



rscotty101 Tue, 08/25/2009 - 06:13
User Badges:

The Linksys router is connected via the WAN port to the Cisco Router and it is set to get its WAN IP address via the Cisco router. We use the Linksys router to segregate the Server and Client off of the guest network, but we need Internet access, hence the Linksys router. We have to swap out the Linksys router with a different one everytime we lose power. It is like the Cisco is tracking the MAC address of the rotuers.

Thank you.

rscotty101 Tue, 08/25/2009 - 06:16
User Badges:

Yes it is acting as a router. We are using the DHCP from the Cisco router since it also provides Internet connections to guests. The Linksys is connected via the WAN port to the Cisco router. Everything will come back up and connect properly with the exception of the Linksys router after a power failure. We have to replace it with a different one everytime.

pompeychimes Tue, 08/25/2009 - 11:14
User Badges:
  • Bronze, 100 points or more

After the power is restored is the linksys able to pull an IP from the DHCP Server aka Cisco Router?

rscotty101 Tue, 08/25/2009 - 19:22
User Badges:

That is the strange part. The Cisco router will not issue a new IP address to the Linksys, so matter what we do, even a power reset. As soon as we install a brand new Linksys router, the Cisco Router will issue a new IP and things are fine...until the next power outage, then it starts all over again.

pompeychimes Wed, 08/26/2009 - 11:16
User Badges:
  • Bronze, 100 points or more

OK, so put a static on the Linksys and see if it is able to communicate with the Cisco.

rscotty101 Wed, 08/26/2009 - 19:14
User Badges:

We have tried that already. The router will not allow any data to pass thru it coming from that Linksys after a power failure. Do you know if the router has the ability to disallow traffic based upon a MAC address?


pompeychimes Wed, 08/26/2009 - 19:39
User Badges:
  • Bronze, 100 points or more

Sorry to persist but can the linksys and cisco ping or arp each other? To test do a ping from the Cisco to the static IP on the Linksys. Assuming the ping fails do a "sh arp | i Linksys static IP" on the Ciso right after the ping fails and see if you see the Linksys' MAC address in the command output. If you don't see it do you see the word "incomplete" or do you see nothing at all?

rscotty101 Fri, 08/28/2009 - 05:53
User Badges:

I will be on site next week so I will try it then. I guess I will need to make it fail before trying this correct? Is there any way the Cisco is tracking MAC addresses and once it has a failure, it keeps hold of those addresses and doesnt allow them to connect properly?

Thanks for all your help!

rscotty101 Mon, 08/31/2009 - 20:46
User Badges:

Hi Again,

I set the static IP address on the Linksys router, yet the Cisco rotuer will not pass information to the Internet. I can ping between each other. Does the Cisco maintain a denial list based upon MAC addresses? If so, is there a way to clear it so I can reuse the Linksys routers?

Thanks again for all your help!

pompeychimes Thu, 09/03/2009 - 18:52
User Badges:
  • Bronze, 100 points or more

Yes, the Cisco can maintain a denial list based on MAC addresses. Please post the Cisco config for furhter analysis.

nsn-amagruder Thu, 09/03/2009 - 19:25
User Badges:

Are there any devices (i.e. Switch/Hub) between the Linksys router and Cisco Router? I've seen switchports not allow traffic until the device / port is reset after these types of events.

Are the devices on the lan side of the linksys still able to access the linksys?

Access the web interface of the linksys, does the WAN interface get an IP Address?

Out of curiosity, why don't you segment the traffic with an ACL and subinterfaces on the 1800?


NonStop Networks


This Discussion