I need to setup load balancing on my cisco 1720. But not the same way most
of the people would do.

I have 2 T1 connected to the router and the FastEthernet port connected to a
hub.
The Hub is connected to 2 web servers. I would like the device to route
packets to the second server if the first goes down.

Is this technically possible ?

PS : I do not have direct control over my DNS entries, I have to call my ISP
whenever I need to make a change.



Thanks

In article <bt4kv2$jb7$1@news.iquest.net>,
 "Pascal Duchemin" <pascal@dorseyinc.com> wrote:

> I need to setup load balancing on my cisco 1720. But not the same way most
> of the people would do.
> 
> I have 2 T1 connected to the router and the FastEthernet port connected to a
> hub.
> The Hub is connected to 2 web servers. I would like the device to route
> packets to the second server if the first goes down.
> 
> Is this technically possible ?

This doesn't sound like load balancing, it sounds like failover.  Load 
balancing would be if you wanted traffic to go to both servers 
concurrently.

I don't think there's any way for the router to do this by itself.  
Cisco Local Director can do it, though.  And the server OS vendor might 
have clustering software that can do it on the servers.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA

"Pascal Duchemin" <pascal@dorseyinc.com> wrote in message
news:bt4kv2$jb7$1@news.iquest.net...
> I need to setup load balancing on my cisco 1720. But not the same way most
> of the people would do.
>
> I have 2 T1 connected to the router and the FastEthernet port connected to
a
> hub.
> The Hub is connected to 2 web servers. I would like the device to route
> packets to the second server if the first goes down.
>
> Is this technically possible ?

That's not how routers work.  8-)  They route the the address requested.  As
Barry noted, you can use Local Director.  Or a web cache.

You may also want to use NAT, where you can use an address for your web
server, and translate it to either server 1 or server 2, and flip manually
when one goes down.

Ideally, you should get control of your DNS, since that is the cleanest way
to manage web server readdressing.  At least have them delegate a subdomain
to you.

I think "IP SLB" is what you need - see
http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_command_reference_chapter09186a00800873c2.html.

Don Woodward

"Pascal Duchemin" <pascal@dorseyinc.com> wrote in message
news:bt4kv2$jb7$1@news.iquest.net...
> I need to setup load balancing on my cisco 1720. But not the same way most
> of the people would do.
>
> I have 2 T1 connected to the router and the FastEthernet port connected to
a
> hub.
> The Hub is connected to 2 web servers. I would like the device to route
> packets to the second server if the first goes down.
>
> Is this technically possible ?
>
> PS : I do not have direct control over my DNS entries, I have to call my
ISP
> whenever I need to make a change.
>
>
>
> Thanks
>
>

In article <barmar-A5A936.15575502012004@netnews.attbi.com>,
Barry Margolin  <barmar@alum.mit.edu> wrote:
>In article <bt4kv2$jb7$1@news.iquest.net>,
> "Pascal Duchemin" <pascal@dorseyinc.com> wrote:
>
>> I need to setup load balancing on my cisco 1720. But not the same way most
>> of the people would do.
>> 
>> I have 2 T1 connected to the router and the FastEthernet port connected to a
>> hub.
>> The Hub is connected to 2 web servers. I would like the device to route
>> packets to the second server if the first goes down.
>> 
>> Is this technically possible ?
>
>This doesn't sound like load balancing, it sounds like failover.  Load 
>balancing would be if you wanted traffic to go to both servers 
>concurrently.
>
>I don't think there's any way for the router to do this by itself.  
>Cisco Local Director can do it, though.  And the server OS vendor might 
>have clustering software that can do it on the servers.
>
>-- 
>Barry Margolin, barmar@alum.mit.edu
>Arlington, MA

The correct answer, as Barry points out, is to implement your two web
servers as a single cluster. This would buy you not only failover, but
also true load sharing. 

Cisco's Server Load Balancing protocol is an option if your traffic is
heavy enough to permit detection of dead servers with an acceptable 
percentage of lost packets. IOS and/or router platform upgrade may be
required to make it work, so check before committing.

Assuming these are not an option, your requirement sounds simple enough
you may be able to cheat! But you still need your web servers to
help out! You would do a variation on the dual-homed host approach
discussed in Chapter 3 of my book (which addresses generally the
problem of network to server redundancy).

1 - Put the IP address of the web server on a loopback port defined on
    both hosts.

2 - Change the LAN to use a different (RFC 1918?) address range.

3 - Run a routing protocol between the hosts and the router so the
    router can learn about the loopback IP.

4 - Adjust the routing distance (on the hosts or on the router, either
    would work) so the primary host is the preferred route.

5 - Keep in mind that any time you switch between servers, all TCP
    connections will be lost and need to be reestablished. Ditto any
    other services, such as SSL, which require state information to
    be maintained for more than a single IP packet.

Good luck and have fun!
-- 
Vincent C Jones, Consultant           Expert advice and a helping hand
Networking Unlimited, Inc.            for those who want to manage and
Tenafly, NJ  Phone: 201 568-7810      control their networking destiny
http://www.networkingunlimited.com

In article <gcnJb.5$Fz1.1@fe01.usenetserver.com>, none@none.com says...
> I think "IP SLB" is what you need - see
> http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_command_reference_chapter09186a00800873c2.html.
> 

And it works on 1720? Since when?

-- 
Ivan

"Ivan Ostres" <john@fly.srk.fer.hr> wrote in message
news:btbib8$5d97k$4@ID-61273.news.uni-berlin.de...
> In article <gcnJb.5$Fz1.1@fe01.usenetserver.com>, none@none.com says...
> > I think "IP SLB" is what you need - see
> >
http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_command_reference_chapter09186a00800873c2.html.
> >
>
> And it works on 1720? Since when?
>
> -- 
> Ivan


Good point - looks like SLB only works on a 36xx or 72xx series on 12.3
according to the Cisco Feature Navigator. The command first appeared in 12.0
according to the IOS documentation

Don Woodward