Question about setting up a highly redundant small network for one mission critical application running on a single server with a dual nic.

Posted on 2004-04-02
Last Modified: 2013-11-09
Hi I am trying to make a complete highly redundant small network for one mission critical application running on a single server. I want to use one server with dual network cards using the same IP, 2 Cisco switch and 2 Cisco routers each connected via separate T1s to the same provider (direct connection – separate POP (loops))

I need to have it so that if one of the server’s network cards, a switch and a router fail I will still have network connectivity to my destination.

Cisco 26xx router = router1
Cisco 26xx router = router2
Catalyst 29xx = switch1
Catalyst 29xx = switch2
ServerA dual nic port1 = ServerAnic1
ServerA dual nic port2 = ServerAnic2

GENERAL Connection:
ServerAnic1—switch1—router1—direct connection same location as router2-PROVIDERa
ServerAnic2—switch2—router2—direct connection same location as router1- PROVIDERa

I need to see if I can get redundancy for the following. (if it not possible for both I need at least #1.)
1. ServerAnic1 and router2 FAIL, both switches up.
2. ServerAnic1, switch1 and router2 FAIL.

Is this possible? If so, what Cisco switches and routers models would I need?

Briefly, what would the configuration of the switch and router look like?

Would I use a 2621 and plug one of the Ethernet ports into each switch?
Would I hook one of routers Ethernet ports to the other router?
Would it be the switch or the router which the failure would be resolved with?
What would be the HSRP configuration?
Would I need a switch that does internal routing?
Would I need to just have 1 cross-over between each switch?
Would there be a problem caused by having one IP address for the server (set by Load balanced or fault tolerance) and plugging each network card into a different switch?

Thanks you for your help.
Question by:noelwhite
  • 2
LVL 27

Assisted Solution

pseudocyber earned 20 total points
ID: 10745163
I would do it like this:  Server both NICs one each into the switches.  The switches tied together with multiple ports "bonded" with Etherchannel.  You could team the NICs on the server with some kind of NIC teaming and possibly include the Cisco side with Etherchannel - depending on your OS, the NICs, and their drivers.

Connect the two routers to the two switches and use HSRP as the default gateway.

On the server, you need to make sure it's designed for HA (High Availability) including:
RAID 5 at least - 3 drives hot with a hot standby.  RAID controller managing RAID - NOT SOFTWARE.
For very high availability, multiple controllers and arrays.  For very very high availability - redundant servers and/or sites.
At least two power supplies in the server connected to two differenc circuits both of which have UPS and possibly generator backup.
Verified and tested backup solution.

Having one ISP is not redundant - odds are the connections come in over the SAME path (read suceptible to backhoes) and are connected to the SAME equipment on the provider's end.

Finally, if you would like more detail, I would recommend upping the points for this question.


Author Comment

ID: 10745497
i am looking for the specifics in the configuration beyond what i have stated between the 2 nics and the 2 routers. I have an idea of the setup it just the fine detail. The grey area are how exactly to plug the routers in to the switches, i.e. e0 router1 to switch1 and e1 router1 to switch2 and the same for the other router?? Would router1 e0 be in a group with router 2 e0 which both plug into the same switch1?  also, if there is a problem having a teamed nic plugged into different switches, and finally is there any is special setting that i need to do on the switches in this configuration which would be compared to having to do HSRP on the routers?


Author Comment

ID: 10750873
This is really the part of the configuration that i need the answer to.

            2621                           2621
         E0          E1                E0         E1
          |           |                  |             |
     Switch1   Switch2       Switch1   Switch2  all on the same subnet.

I know I do HSRP between the 2 routers so if a router fail the packets are routed out the other router.

Side NOTE: A server with dual nics uses SFT - switch fault tolerance to plug a nic into each switch and if one switch goes down then the other nic will become active and failover to the backup switch. Is there a similar thing for the routers?

MY main question is how can I configure the routers to have switch redundancy, i.e. if one switch fails my server will still have access via the working switch to BOTH routers?  

If so, can you please let me know what the config would look like?

Accepted Solution

Pascal666 earned 120 total points
ID: 10754132
First router:
bridge irb
interface FastEthernet0/0
 bridge-group 1
interface FastEthernet0/1
 bridge-group 1
interface BVI1
 ip address
 standby ip
 standby priority 105
 standby preempt
 standby track  Serial0/0:0
bridge 1 protocol ieee
bridge 1 route ip

Second router:
bridge irb
interface FastEthernet0/0
 bridge-group 1
interface FastEthernet0/1
 bridge-group 1
interface BVI1
 ip address
 standby ip
 standby preempt
 standby track  Serial0/0:0
bridge 1 protocol vlan-bridge
bridge 1 route ip

Note that due to an IOS bug the two have to run different spanning tree protocols.


Featured Post

Free Tool: IP Lookup

Get more info about an IP address or domain name, such as organization, abuse contacts and geolocation.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Sharing same loopback address on different switches 1 48
Line cards, Supervisor, Control plane 7 52
winscp 6 73
Manage ASA using outside IP 14 62
Short answer to this question: there is no effective WiFi manager in iOS devices as seen in Windows WiFi or Macbook OSx WiFi management, but this article will try and provide some amicable solutions to better suite your needs.
I had an issue with InstallShield not being able to use Computer Browser service on Windows Server 2012. Here is the solution I found.
After creating this article (, I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
Internet Business Fax to Email Made Easy - With  eFax Corporate (, you'll receive a dedicated online fax number, which is used the same way as a typical analog fax number. You'll receive secure faxes in your email, f…

856 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question