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I have recently acquired a Cisco 2801 unit and I want to know if it is capable of acting as a fail over for a network. It currently has an ADSL WIC installed.

We currently run 6 Windows servers (4x Win2008, 2x Win2000) with TS access for our users. This runs over a cable modem connection. We also have an ADSL connection which we want to use as a failover should the cable connection go down.

My question is this: Can the 2801 we have be used to do what I require? If so, would it be difficult to set up, and are there any known complications with this kind of failover? If not, can anybody suggest an alternative?

Thanks

Sangai
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    *Citrix* 2801?! Cisco, surely... – Alnitak May 20 '09 at 13:46
  • I think I'm going to give up on the Cisco for now. I don't know anything about them, it was just a box I acquired and thought it might be good to try it. Thanks for all your answers. – Sangai May 21 '09 at 09:59

4 Answers4

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I'm going to assume that you mean a Cisco 2801 unit.

Unfortunately we've insufficient information to go on:

  • What physical interfaces apart from the ADSL WIC does the 2801 have?
  • What physical interface does the cable connection have?
  • Do you have NAT on either of the connections?
  • Do you have static IP(s) on either of the connections?

EDIT - based on your additional comments.

I recommend you:

  1. Make sure you can get a static IP block on the ADSL line
  2. Install a firewall capable of dual WAN line operation (I've had good results with Stonegate units - that link goes to their primary UK supplier and integrator)
  3. Give your users the secondary IP addresses from the ADSL line to use as necessary

Handling the inbound connections is actually slightly tricky, because if a user connects on the DSL line you have to ensure that the outgoing response packets go out via the same link. The firewall should be able to handle that for you.

Alnitak
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  • The 2801 has 1 USB port and 4 ethernet links (FE 0/1, FE0/0, CONSOLE and AUX) Of the 4 expansion ports, only SLOT 2 is populated with the ADSL WIC. Cable connection is a simple ethernet output from the cable modem. All of our servers are currently running with static, public IP's. Our internal network is running on DHCP through the cable connection. The ADSL connection is currently not being used, but is tested often and is still live. – Sangai May 20 '09 at 15:04
  • oh dear... The CONSOLE and AUX ports aren't ethernet, even though they might look like it. – Alnitak May 20 '09 at 15:44
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    so, do all of the servers have a direct connection (albeit through a switch) to the cable modem, or is there (hopefully!) a firewall between them? – Alnitak May 20 '09 at 15:45
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The answer is a qualified 'yes'. Since this would be an active/backup situation, you should be able to do what you want with floating static routes. The challenge will be with your users connecting to the servers when you fail-over to the backup link. The IP address will change and unless you use some type of DNS updating service, they will need to change their shortcuts or have two icons on their desktop.

You will need to connect ISP1 and ISP2 to the 2801 and it then to your switch. Next setup a static route on the 2801 to point to ISP1 and a second static route to ISP2 with a high administrative cost.

By the way as Alnitak said, you should know that the 'CON' and 'AUX' ports are not Ethernet. They do use CAT5 cabling, but are not network ports. This may leave you short of the necessary three for this solution to work.

Also based on your comments, it sounds like you may not have a firewall? If this the case RUN, do not walk, and get one immediately. It would also probably be a good idea to change your servers to private addressing and then do NATs on the firewalls.

Peter
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assuming you can do tracking routes you certainly can we use something like this

ip route 0.0.0.0 0.0.0.0 ip.to.gateway1 track 100
ip route 0.0.0.0 0.0.0.0 ip.to.gateway2 2

then you can create your tracking like so

track 100 rtr 1 reachability
delay down 30

in reference to something like this 

ip sla monitor 1
type echo protocol ipIcmpEcho ip.to.next.hop
frequency 10

you would set ip.to.next.hop to a next hop address ... find it using tracert if that goes down your ip route will be removed and it will fall back on your default route.

trent
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  • note this will only give you access out ... if your servers as serving a website etc etc you will need to do something with dns to make connections come in to the right place – trent May 20 '09 at 17:45
  • Don't floating static routes accomplish the same thing without the extra complexity of the route tracking? – Peter May 20 '09 at 17:49
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I came across the following linux distro that may do what you are looking for:
[In particular the WAN fail-over.]

While not a direct answer to you, I hope this answers the intent if not the specifics of your question.

http://www.untangle.com/
  • Active Directory Connector
  • Attack Blocker
  • Branding Manager
  • Commtouch Spam Booster
  • eSoft Web Filter
  • Firewall
  • Intrusion Prevention
  • Kaspersky Virus Blocker
  • OpenVPN
  • PC Remote
  • Phish Blocker
  • Policy Manager
  • Protocol Control
  • Remote Access Portal
  • Reports
  • Routing & QoS
  • Spam Blocker
  • Spyware Blocker
  • Virus Blocker
  • WAN Balancer
  • WAN Failover
  • Web Filtering
Peter
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