Question

Cisco IOS - Need to NAT Inbound traffic, as well as Outbound

Asked by: ccfcfc

I am trying to get round a problem I am having with Windows load balancing using NAT.

My scenario is this -

I have a group of users that connect to a website behing my Cisco router. I have two web servers which are running under Windows NLB. The users all connect to the web servers using the same IP address as they are NAT'd to the outside interface public IP at their end, which means that NLB sends them to the same web server every time as they are all on one IP address. This obvioulsy means that I am not getting any load balancing on my web servers.

What I would like to do is NAT the incoming traffic to an address pool, so that each of the incoming web sessions from the remote users then has an individual IP address allocated from the pool that I have setup. This would then mean that NLB would spread the connections much more evenly between the web servers.

The question is - do I use the same NAT statements as I would normally use for outgoing NAT ? As long as my NAT statement refers to the address that the users web sessions are coming from, then the NAT pool will still apply even though the traffic is incoming ?

i.e. Will the following work, allowing the remote users coming from 94.7.28.1 to access my web servers on a 10.10.10.x address ?

ip nat pool webuser 10.10.10.1 10.10.10.50 netmask 255.255.255.0
ip nat inside source list 1 pool webuser
access-list 1 permit host 94.7.28.1


TIA


Rob

This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

  • Plus...
  • 30 Day FREE access, no risk, no obligation
  • Collaborate with the world's top tech experts
  • Unlimited access to our exclusive solution database
  • Never be left without tech help again

Subscribe Now

Asked On
2007-09-24 at 08:05:34ID22848460
Tags

cisco

,

nat

,

ios

,

inbound

Topics

Network Routers

,

Cisco PIX Firewall

Participating Experts
1
Points
500
Comments
4

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

  • "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
  • "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
  • "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.

Screenshot of Experts Exchange Knowledgebase

Need individual assistance?

Our experts are ready to help.

If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.

Screenshot of Experts Exchange Knowledgebase

Want to learn from the best?

Read articles from industry experts.

Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.

Screenshot of an Article

Working on a long term project?

Store your work and research.

Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.

Screenshot of Experts Exchange Knowledgebase

Access the answers to your technology questions today.

Subscribe Now

30-day free trial. Register in 60 seconds.

What Makes Experts Exchange Unique?

Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Trusted by the world's most respected brands.

image of each brand's logo

Faithfully serving IT professionals since 1996.

Experts Exchange Logo

Try it out and discover for yourself.

Subscribe Now

30-day free trial. Register in 60 seconds.

Related Solutions

  1. Cisco Catalyst (NAT) ??
    Hi, Is the Cisco Cat vesion capable of performing a natting on the routing module ? Need a confirmation, if yes do you have any sample on this ?? Thanks.
  2. Cisco NAT 1841
    Question using NAT, my ISP gave my 2 subnets one for the WAN Interface and one for my Lan internface. But I need the Cisco to do NAT. How do I configure? I need to use the second subnet for static nats. if i do this, it works fine but I need to use the second subnet for the ...
  3. Cisco Natting
    Dear EE I had two 5 public ip let say X.X.X.5 ------ x.x.x.9 and I had full class C network with 400 subscribe now I make all 400 subscribe NAT to one Public IP and leave the other 4 free !!?? because I don't know how to make NAT all 400 with 5 public I think its like that...
  4. Cisco NAT
    How do I configure the NAT settings on cisco. If you look ay my config, I am able to access the internet when I have a 172.16.0.X ip address on local machine. But computers from another subnet, such as 10.10.2.X cannot access the internet. Can anyone be able to help me settin...

Free Tech Articles

  1. WARNING: 5 Reasons why you should NEVER fix a computer for free.
    It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
  2. SCCM OSD Basic troubleshooting
    SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
  3. Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
    This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
  4. Create a Win7 Gadget
    This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
  5. Outlook continually prompting for username and password
    There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
  6. Backup Exchange 2010 Information Store using Windows Backup
    There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...

Cloud Class Webinars

  1. Avoiding Bugs in Microsoft Access
    Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
  2. Top 10 Best New Features in Visio 2010
    Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
  3. IT Consultant Business Secrets Revealed
    Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
  4. Disaster Recovery and Business Continuity
    Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
  5. Organize Your Visio Diagrams with Containers and Lists
    Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
  6. How to Us Objects, Properties, Events and Methods in Microsoft Access
    Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...

Join the Community

Give a Little. Get a Lot.

Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.

Join the Community

Answers

 

by: tlamoniaPosted on 2007-09-29 at 19:04:44ID: 19985941

Rob,
Sounds like your NLB config is not setup correctly.  The source IP shouldn't matter, it's the NLB virtual IP that matters in this case.  Please reply with more info about your NLB setup.
-Todd

 

by: ccfcfcPosted on 2007-09-29 at 20:01:22ID: 19986037

tlamonia,

From the information I have been able to gather, NLB works by sending traffic to a virtual IP shared between the NLB member servers, but the session state is based on the source IP address. If all of the users connecting to my web servers are all NAT'd at source to a single IP address, the first server that they are sent to as they pass through NLB will then be the server that everything from that IP address is sent to.

If that server dies, NLB will handle that and send all subsequent sessions to another server in the NLB pool, but the same thing will happen - the first server that the first connection hits will be the same server that all subsequent connections are sent to.

This setup gives me resilience in the event of server failure, but what it doesn't give me is any form of load balancing whatsover. It doesn't matter how many servers I have in my NLB pool, only one is ever being used which removes my ability for capacity management.

Please let me know if any of my assumptions here are incorrect, but nothing I've been able to find either via information sourced on the Net, or as a result of all of the testing I have done, has shown me anything other than the above - once an IP address hits one server under NLB that's the server any subsequent traffic from that same address will go to.

Thanks.

 

by: tlamoniaPosted on 2007-09-29 at 20:14:16ID: 19986058

What are your NLB settings?
1) What's your affinity parameter set to?  It should be None.
2) What port rules do you have setup?
-Todd

 

by: tlamoniaPosted on 2007-09-30 at 19:12:16ID: 19988592

Rob,
Regarding your original question about reverse NAT.  You're on the right path.  Here's the correct config:
ip nat pool webuser 10.10.10.1 10.10.10.50 netmask 255.255.255.0
ip nat outside source list 1 pool webuser add-route
access-list 1 permit host 94.7.28.1
Give that a shot and let me know if it works for you!
-Todd

20120131-EE-VQP-002

3 Ways to Join

30-Day Free Trial

The Experts

98% positive feedback on 31,087 answers since March 2000. angeliii is a Microsoft Most Valuable Professional for his work with MS SQL Server & Develoment.

He has also proven his knowledge of Visual Basic Programming, PHP Scripting and Oracle Databases.

The Experts

97% positive feedback on 10,752 answers since July 2000. lrmoore has more than 18 years experience in the networking industry.

The six-time Mircosoft MVPs specialties include firewalls, virtual private networking, and network management.

Testimonials

"...and excellent source for support... Kind of like having your very own IT dept." Electriciansnet

Testimonials

"I was apprehensive at signing up at first. However... it has already made my life as an IT administrator much easier." JaCrews

Testimonials

"WOW! You guys have great, active, and knowledgeable people on here." moore50

Business Clients

Business Clients

In the Press

"If you’ve got a question... Experts Exchange can supply an answer.”

In the Press

"...an invaluable aid for both IT professionals and those who require tech support."

In the Press

"where IT professionals provide quick answers on just about any topic"

Business Account Plans

Loading Advertisement...