Ios slb configuration

Hi guys, need help with configuring cisco slb for 2 microsoft exchange servers. Have created server farm for the 2 servers, configuration works. Problem is user logs onto the domain, then when opening outlook, user is required to log in again. Now if we edit hostfile on client pc with one of the server addresses which means bypassing slb routing, then user only lgs in once to the domain, when user opens outlook it does not prompt him for credentials, which the user prefers. Anyone with slb experience who can shed some light ? Is ths an slb issue or a server issue. My slb is configured in direct mode and no sticky configured.
ip slb serverfarm SERVERFARM
nat server
real 10.122.xxx.xxx
weight 2
inservice
real 10.122.xxx.xxx
weight 1
inservice
ip slb vserver VSERVER
virtual 10.123.xxx.xxx tcp smtp
serverfarm SERVERFARM
inservice
ip slb vserver VSERVER_HTTPS
virtual 10.123.xxx.xxx tcp https
serverfarm SERVERFARM
inservice
ip slb vserver VSERVER_WWW
virtual 10.123.xxx.xxx tcp www
serverfarm SERVERFARM
inservice

Justin,
you'll need to perform the math manually (or within a script).
Get the number of conn every x sec and make (o2 - o1)/x to have conn/sec
Gilles.

Similar Messages

IOS SLB conns/sec

Hi is it possible to get a conns/sec statistic from the IOS SLB configuration. I can only see conns and max conns etc. I'm trying to get a figure to use so that I can compare it to max conns/sec. I gather IOS SLB is capable of 20k max conns/sec with the 720BXL.
Thanks

Justin,
you'll need to perform the math manually (or within a script).
Get the number of conn every x sec and make (o2 - o1)/x to have conn/sec
Gilles.

IOS SLB versus CSM

Hi,
trying to figure out a possible solution for a 6500 and got a bit confused. According to my knowledge, IOS SLB is working either in L2 (MAC) or L3/4 (NAT), to ensure load balancing. CSM comes in the game, but offers much more, extending to L4/7. Are the two solutions substitude or complementary? Is it true that only with an CSM can you get HTTP probes to check your load balanced server farm? What other differences do you know about these two solutions?
In the paper http://www.cisco.com/en/US/partner/products/hw/modules/ps2706/products_configuration_example09186a0080094066.shtml
it is stated that "To run Cisco IOS SLB software, you must configure the mode using the show ip slb mode [csm | rp] command before any configuration. In the show ip slb mode command, the rp argument is default. You can only configure csm argument if you have the Content Switching Module (CSM)."
While in
http://www.cisco.com/en/US/partner/products/hw/modules/ps2706/products_configuration_example09186a008009452d.shtml
cisco states that "You cannot run Cisco IOS® SLB software on the same switch as the CSM."
Any ideas on that?
Thanks in advance

there are 2 ways to configure the csm.
You can use the same ios slb command and just tell the switch that there is a csm with the command 'ip slb mode'.
Or you can use the 'module contentswitching ' command.
If you use the first method, you can't use both a CSM and ios slb on the same switch.
If you use the second method, it is ok to have both ios slb and csm.
IOS SLB offers L4-7 loadbalancing solution.
Just be aware that as soon as you do L7 or do some nating, you poor performance with ios slb compare to a CSM.
One advantage of ios slb is the capacity to do radius loadbalancing [inspecting radius packet to identify framed ip, ...]
This is why in CMX solution we combine both ios slb and csm.
IOS SLB is used to loadbalance radius and the CSM is used to loadbalance the rest of the traffic.
Personally, I would say if you just need some vpn or firewall loadbalancing, ios slb is enough.
If you need HTTP or any other traffic wthe CSM is a better choice.
Regards,
Gilles.

IOS SLB dns probe

Hi,
I'm trying to configure a DNS probe using IOS SLB, but it's not working.
I followed the manual on how to configure a DNS probe, but it just doesn't make any sense.
When using DNS probes on an ACE, you give a hostname which the DNS server should resolve to a configured IP Address.and configure an ip address, which makes sense.
On the IOS SLB, it is not the case. Two variables can be configured:
Router(config-slb-probe)# address ip-address]
(Optional) Configures an IP address to which to send the Domain Name System (DNS) probe.
Router(config-slb-probe)# lookup [ip-address]
(Optional) Configures an IP address of a real server that a Domain Name System (DNS) server should supply in response to a domain name resolve request.
What am I missing. Could someone please clearify??
Tnx!

To verify that a probe is configured correctly, use the show ip slb probe command:
Router# show ip slb probe
It may help you in troubleshooting purpose
For the further description for configuration for the DNS Probe following guide may help you
http://www.cisco.com/en/US/docs/ios/12_2/12_2z/12_2za/feature/guide/slbza5.html#wp2434837

IOS SLB and FWSM

Hi, this may be a silly question but is there any problem with configuring IOS SLB on a 6509 which also has a FWSM module in it and the Servers being load balanced are behind the FWSM?

The only thing to consider is that by FWSM, you most likely will be running multiple VRFs on the switch and IOS-SLB has some limitations regarding VRF.
IOS-SLB probes are sent to the global routing table (VRF default) and you will need to 'no advertise' and add static routes to null0 to the VRF for the virtual IPs.
Other than that, IOS-SLB works fine with the FWSM and VRF...

CSM - IOS SLB failover ?

I can't see this from the documentation, but as far as I can see the configuration commands on the switch are the same for IOS SLB and for the CSM. Does this mean that if you have an CSM which fails, the subset of functions supported by IOS SLB will be ?
I realise performance would be less and only 500 VIPs would be supported etc.
Thanks
Simon

Simon,
I do not think this is the case. If you look closely at the configuration you will see the command ip slb mode csm. This causes all SLB functions to be offloaded to the CSM. The default is ip slb mode rp which is IOS based. If the CSM fails then SLB will stop working. You will need to enter the command ip slb mode rp for it to work again.
If you are running version 2.1 or above it is recommended you run ip slb mode rp and use the configuration command
module ContentSwitchingModule X where X is the module number
and the slb commands under this.
Cheers
Phil
Cheers
Phil

IOS SLB - Samba

Hi,
Is it possible, and can anyone provide an example, to configure IOS SLB for Samba services ?
Thanks

Thanks for the response Ivan,
My level of account access wont allow me to view the link you have provided
Here's what I am looking at trying to achieve....
We have a file system that is accessed by many clients, the access is via a proprietary protocol. In order to support generic client access we mount the file system, using our own driver and share it as a Samba share. The systems hosting this Samba share are used for client access.
So, we could potentially have multiple machines hosting the same file system via Samba.
I would like to be able to present this architecture as an N+1 resilience model, which would require load balancing and failover on the machines hosting the Samba mount. IOS SLB seems like the right approach on paper, especially if you substitute Samba for FTP as an example.
One concern I do have is whether the throughput is constrained by utilizing SLB. Do you have any comment on this ?
I will look to see if I can dig up any L4 LB papers elsewhere in the mean time.
Thanks for your input thus far.

IOS SLB HTTP Probe

Hi, I have a simple SLB setup with two servers running in directed mode and two 6509's running IOS SLB to balance between the two. The two servers are web servers and require authentication when hit so I am just testing using a http probe and searching for the 401 code. Is there any gotcha's with configuring the credentials on the 6509 to log onto the webpage? Cheers, Brian

Can you post the following:
1. debug ip slb probe
2. debug ip slb probe conn
3. debug rtr error
4. debug rtr trace

IOS SLB maximum connections

Hi,
New to this Forum, at least. Apologies if this is not appropriate for SLB questions...
We have a standard IOS SLB setup with 2 x Cisco3725's running HSRP. IOS SLB setup for a few servers on private LAN. They're running www, ftp, https.
We have a customer who needs figures for maximum connections supported for www, for example.
We currently monitor the basic's(bandwidth :) ) via MRTG.
Has anyone an idea how we would go about trying to estimate max xonnections for our setup. Are there general scalability guidelines on CCO?
Thanks,
Mark

The Cisco IOS Server Load Balancing (SLB) feature is a Cisco IOS-based solution that provides server load balancing. This feature allows you to define a virtual server that represents a cluster of real servers, known as a server farm. When a client initiates a connection to the virtual server, the IOS SLB load balances the connection to a chosen real server, depending on the configured load-balance algorithm or predictor. To monitor HTTP access you could use the HTTP proble feature that is supported with IOS server load balancing. For more information refer to the following document.
http://www.cisco.com/en/US/products/hw/modules/ps2706/products_configuration_example09186a0080094066.shtml

IOS SLB

Hi
I have configured IOS SLB vserver and serverfarm. There is a list of allowed clients.
But from two clients (with IP 10.171.4.*) there is Reset of connections. Other clients works OK.
ip slb serverfarm SF1
probe SF8888
real 10.91.14.90
weight 1
faildetect numconns 4
retry 20
inservice
real 10.91.14.91
weight 1
faildetect numconns 4
retry 20
inservice
ip slb vserver VS1
virtual 10.91.14.19 tcp 8888
serverfarm SF1
idle 120
delay 5
client 10.91.14.32 255.255.255.255
client 10.91.14.38 255.255.255.255
client 10.91.14.41 255.255.255.255
client 10.91.15.30 255.255.255.255
client 10.91.15.31 255.255.255.255
client 10.171.4.64 255.255.255.255
client 10.171.4.65 255.255.255.255
inservice standby WA-SLB-1
Peter

Howdy,
You might want to post this in the application networking area :-)
Cheers
Andrew

IOS SLB and probe failure

Hello,
we use server-load-balancing with IOS 12.1(19)E1
We have a problem if the server receives more connections following error messages REAL 192.168.197.8 (HSSAT1-LX) has changed to PROBE_FAILED and few seconds later REAL 192.168.197.8 (HSSAT1-LX) has changed to OPERATIONAL appears and so on.
We checked the server and they works proper.
What could be the reason for probe failed?
My configuration:
ip slb probe HS-PROBE tcp
interval 5
ip slb serverfarm HSSAT1-LX
nat server
predictor leastconns
failaction purge
probe HS-PROBE
real 192.168.197.8 99
reassign 2
inservice
real 192.168.197.9 99
reassign 2
inservice
ip slb vserver HS.SAT1.DE
virtual xxx.xxx.xxx.xxx tcp www
serverfarm HSSAT1-LX
advertise active
inservice standby allvips
How does a TCP probe works? I could not find more exact information in the documents to configure probes.
Is it better to use another probe (icmp)? or without any probe?
When does it make sense to use probes?
Best regards
Stefan

HI Stefan,
tcp probes do a complete TCP 3-way handshake and normaly terminate the session. A problem which I had some times timeout for a session to be established might be to short if the server is "heavy" loaded.
Probing on a specific method (TCP HTTP ...) is most of the times the better solution. Imagine a WEB-Server which is properly pingable but the httpd died due to some internal error. If you would probe on a per ping basis the loadbalancer will never notice this but if you monitor tcp-port 80 by a tcp probe or better a http probe you will notice this and the server would be taken out of the serverfarm. Even better but afaik not possible in IOS SLB is to probe a certain page e.g. index.html. As you know that the httpd is up and running and pages can be displayed.
Regarding the probing issue it might be usefull to read the follwing link describing healthmonitoring with the CSM
http://www.cisco.com/en/US/products/hw/switches/ps708/products_installation_and_configuration_guide_chapter09186a00801c5899.html#1024967
Hope that helped.
Best Regards,
Joerg

IOS SLB and DNS failover

Hi, there:
Is that possible I could use IOS SLB and DNS failover automatically?
i.e:
vip 10.1.1.1
vip 10.2.1.1
dns records:
vip1 10.1.1.1 10.2.1.1
normal condition:
vip1 will be 10.1.1.1
when 10.1.1.1 failed it will give 10.2.1.1
Is that something it could be done on IOS SLB, or other devices?
real services are udp based.gtp service
Thanks,

Yes, IOS server load balancing and the DNS failover can be done automatically. Is this not working currently? Can you posts the configuration so that we can check where the problem is.

IOS SLB Loab Balance Questions

Forgive me if this is the wrong forum but it was the closest one I found relating to my issue.
I've trying to load balance four of our radius servers using IOS SLB. The config works well and the radius servers are accepting requests fine. I follow this article which wasn't too bad to follow:
http://www.cisco.com/application/pdf/en/us/guest/netsol/ns377/c649/cdccont_0900aecd800eb95f.pdf
My two questions are:
1. Sticky Option
I understand it's used to make sure the client's accounting information
goes to the correct real server, but I'm not sure how it really works
and what's the best time to set it to.
Eg:
ip slb vserver RAD-UDP-1646
virtual 210.x.x.224 udp 1646
serverfarm RADFARM
sticky 86400 group 10
inservice
a/ The documentation says "This configuraion causes the sticky database to store its entries for 86,400 seconds of inactivity". What do they mean by "inactivity" - no radius packets coming through? inactivity from the user's end?
b/ It also says "the client's IP address is added to the IOS SLB database..." - is this the client's framed IP that the ISP assigns to the customer???
c/ And what would be the optimum time to set the sticky timer to be?
2. SLB connection statistics
core1-router#sh ip slb reals
real farm name weight state conns
203.x.x.74 RADFARM 8 OPERATIONAL 0
203.x.x.78 RADFARM 8 OPERATIONAL 0
203.x.x.79 RADFARM 8 OPERATIONAL 0
203.x.x.80 RADFARM 8 OPERATIONAL 2
When you disconnect, the slb stats still show you as being connected to
the real server (and both udp ports) which isn't very accurate. There is a default "delay" time which handles TCP disconnections and after being disconnected for 10 sec, the SLB stats are updated to reflect this (I've verified this works)- but nothing about how it handles UDP disconnections??? This
would skew the stats and give us a very bad misrepresentation of the
number of current and valid connections. Is there anyway to correct this???
Thanks.
Andy

Inactivity for IOS SLB means that after specified time of inactivity, the client will be free to be load balanced to another server. As long as they remain active without an idle time , they will remain connected to the same real server. For the client's IP address which is added to the IOS SLB database I think it is the frammed IP address which the ISP assigns. The optimum time for the sticky timer will be its default value or say 60 seconds.

IOS SLB and IBM Workload Manager

Does anyone know if IOS SLB can function similar to Multinode Load Balancing (MNLB) in that the IOS router acts as a Services Manager which contacts the OS390 Worload Manager (WLM) who then reports back the best OS390 server for a particular connection.
Under MNLB, the Local Director performs the task as the Services Manager, but can a IOS SLB router perform this task?
Thank you for your help.

Steve, thank you for the reply. I have a large-scale OS390 WLM request as I'm told that this is the method for providing server load-balancing in a sysplex environment. I wonder why it is not supported in version 4.X. Do you happen to know the long term goal for OS390 load balancing support?
I appreciate your help, Thank you

IOS SLB RADIUS loadbalancing

Hi Guys,
can anyone confirm or point out errors in this config that I wish to pop on our 6509. We don't have a test environment, so I need to get as much feedback as I can on this.
Thanks in advance,
James
no natpool WSB_RADIUS 10.176.57.115 10.176.57.115 netmask 255.255.255.128
no serverfarm WSB_RADIUS
no serverfarm WSB_RADIUS_NAT
no policy WSB_RADIUS_NAT
no vserver WSB_RADIUS
no probe WSB_RADIUS_AUTH udp
ip slb serverfarm WSB_RADIUS
nat server
real 10.176.57.38
faildetect numconns 8 numclients 1
inservice
real 10.176.57.39
faildetect numconns 8 numclients 1
inservice
real 10.176.57.40
faildetect numconns 8 numclients 1
inservice
real 10.176.57.41
faildetect numconns 8 numclients 1
inservice
ip slb vserver WSB_RADIUS
virtual 10.176.57.115 udp 1813 service radius
serverfarm WSB_RADIUS
idle radius request 2
inservice standby WSB
interface Vlan130
standby 130 name WSB

IOS SLB provides RADIUS load-balancing capabilities for RADIUS servers. In addition, IOS SLB can load-balance devices that proxy the RADIUS Authorization and Accounting flows in both traditional and mobile wireless networks, if desired. IOS SLB does this by correlating data flows to the same proxy that processed the RADIUS for that subscriber flow.
http://www.cisco.com/en/US/products/sw/iosswrel/ps1833/products_feature_guide09186a00802081ce.html#wp2889077

Ios slb configuration

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