Webdispatcher Load balancer issue.

[Former Member]

Hi,

We are using CRM 7.0. Along Central instance we have installed additional 3 more dialog instances for better speed etc.

In the frontend we have installed SAP Webdispatcher for accessing the CRM Application.

Present problem is that when we are giving the url of webdispatcher it is pointing to only 1 application server of the background CRM Servers.

We are unable to route the request from webdispatcher to application servers based on the load.

As a result of load balancing issue we are able to see the http load in only the application server which is connected by Webdispatcher. And the remaining application servers are not being utilized for load balancing.

We have used the below parameter in the webdispatcher for redirecting the request to CRM Application server.

icm/HTTP/redirect_0 = PREFIX=/, TO=/sap/crm_logon?sap-client=900, PORT=80xx, HOST=xxxxxxx.xxxxx.com

Are we doing anything wrong here? Please suggest and help.

[former_member4224 · Accepted solution]

Hi,

if you are using the parameter icm/HTTP/redirect_0 there is no load balance. The web dispatcher only will redirect the connection that match the rule

PREFIX=/

to:

TO=/sap/crm_logon?sap-client=900,

on server:

xxxxxxx.xxxxx.com

IF you want to configure the web disaptcher as load balance you could not use the parameter redirectm, you must use the message server to get the available instances list and also the server port to web dispatcher accept a conenction.

Cheers,

Clébio

[Former Member · Accepted solution]

Hi,

I am sorry to disagree but I use a a lot of redirect parameters on my web dispatcehrs and load balancing works great.

Regards,

Olivier

[former_member4224 · Accepted solution]

Hi,

the parameter icm/HTTP/redirect_ is only used to redirect (code 301).

The 301 is used for permanent redirection. You could not do a load balance with the redirect parameter.

http://help.sap.com/saphelp_nw70ehp1/helpdata/en/48/3d993fb08c72d1e10000000a42189c/frameset.htm

As per documentaion:

"This forces the client to access the new destination instead."

So, there is no load balance in this option. There is no calculation of the load. There are no internal table with the list of stateless requests. Load balance is much more than a simple redirect.. you could create rules to redirect request but this is not a load balance.

The connection that match the criteria will always be redirected to the same server in the parameter, dosen't matter the load of that server. With a redirect option you can also flood the server. So, I don't believe that a redirect could be considerate a load balance.

Cheers,

Clébio

[Former Member · Accepted solution]

Hi,

You don't understand what I'm talking about.

I use redirects on the web dispatcher to simplify URls but the redirect is on the same web dispatcher, so load balancing works perfectly.

Exemple for my SAP Portal

When my users type http://sapportal they are redirected by the web dispatcher to

https://sapportal.company.country/irj/portal

sapportal is the short alias and sapportal.company.country is the alias FQDN of the same SAP Web Dispatcher.

I can guarantee you that load balancing works perfectly with this cas of redirect

I don't redrect on one of the application servers as the Message server does for pseudo load balancing.

Regards,

Olivier

[Former Member · Accepted solution]

Hi,

I was planning for downtime of SAP Webdispatcher for implementing the suggestions.

Should I remove the redirect parameter and check for the load balancing.

Or

In the redirect parameter should I mention the Message server hostname and Port.?

Please suggest.

Thanks for valuable information.

Regards,

D S Kumar

[Former Member · Accepted solution]

Hi,

It seems that your web dispatcher configuration file is wrong. Most probably you have something to correct in it.

Check the dev_webdisp trace file.

In the redirect parameter should I mention the Message server hostname and Port.?

When I read this question, I am afraid that you don't seem to understand what is a redirect...

I suggest that you read once more the whole documentation about Web Dispatcher.

Regards,

Olivier

[former_member4224 · Accepted solution]

Hi,

You must configure the message server host and also message server port in these parameters:

rdisp/mshost

ms/http_port

or for web dispatcher 720

wdisp/system_X = SID=<>, MSHOST=<>, MSPORT=<>

The redirect option is only a feature of web disaptcher and of course that you could use it, but if you set the redirect parameter with the option HOST, the requests that match the rule will always be send to the same host

So, if you want to redirect from " PREFIX=/," to TO=/sap/crm_logon?sap-client=900, you should remove the HOST option, otherwise the host "xxxxxxx.xxxxx.com" will always get these requests.

Cheers,

Clébio

[Former Member · Accepted solution]

Hi Clebio Dossa,

Thanks for the valueable suggestion.

In the url i had removed the hostname and port details and taken the restart of Webdispatcher.

It had helped the load balacing.

Regards,

D S Kumar

[jay_b2]

> Present problem is that when we are giving the url of webdispatcher it is pointing to only 1 application server of the background CRM Servers.
>

Are you sure the web dispatcher should point to one application server. How will that balance the load 😮

It should point to the MS and at the MS HTTP port...

[Former Member]

Hi Jay,

In the webdispatcher profile the below parameters are already maintained.

rdisp/mshost = xyz.abc.com

ms/http_port = 8100

It will be help full if you can let us know the the parameter which should be changed.

Regards,

D S Kumar

[Former Member]

Hi,

1. SAP System identification and instance number (examples)

SAPSYSTEMNAME = C11

SAPSYSTEM = 66

1. Describe message server host (example host name)

rdisp/mshost = sidmain# Description of access ports (examples)

icm/server_port_0 = PROT=HTTP, PORT=8855, TIMEOUT=30

icm/server_port_1 = PROT=ROUTER, PORT=22222, TIMEOUT=300

1. Example additional configuration settings:

2. (only needed if defaults are not ok)

1. URL mapping infos (examples)

wdisp/max_url_map_entries = 50

wdisp/url_map_location = /acme/urlinfos

1. URL filtering (example file name)

wdisp/permission_table = cfg/permtab

1. Parameters for HTTPS routing (examples)

2. This example bitmask "masks" the last 12 bits of client

IP addresses,

1. so, for example, 124.94.55.1 and 124.94.55.99 appear to be the

same

wdisp/HTTPS/dest_logon_group = HTTPSGROUP

wdisp/HTTPS/sticky_mask = 255.255.240.0

1. Server infos and info refresh interval (examples)

wdisp/max_servers = 100

wdisp/max_server_groups = 32

wdisp/server_info_location = /msgserver/text/logon

wdisp/group_info_location = /acme/groupinfos

wdisp/auto_refresh = 120

For more information see the below link..

http://sapinsider.wispubs.com/Article/Achieving-Network-Security-and-Secure-Load-Balancing-with-the-...

Regards

[Former Member]

Hi,

If you find that the load is not distributed in the system after active HTTP/HTTPS ports for the message server and activated ICF services for load distribution support, you please check whether the message server has received the necessary information on the load distribution of the Internet Communication Framework (ICF).

For more information please see the following SAP note..

Note 751873 - Problem analysis during the HTTP load distribution

Note 538405 - Composite SAP Note: SAP Web Dispatcher

Regards

[Former Member]

Hi Bhuban,

Thanks for reply,

The information provided by you was helpful in nature.

Can you help me in zeroing the below information which will help in addressing the issue in right direction.

1) The configuration of the Webdispatcher is ok with respect to url redirecting.

2) Configuration w.r.t to defining virtual hosts with common ports for all the app servers and redirecting the Webdispatcher to that particular virtual host many help in overcoming the issue.

Any information on the above will be helpfull.

Note: Default services in SICF w.r.t to load balancing are already activated.

Regards,

D S Kumar.

[Former Member]

Hi,

Can you please look the below link..

http://help.sap.com/saphelp_nw70/helpdata/en/be/6041418e998739e10000000a1550b0/frameset.htm

Regards

[Former Member]

Hi,

Please check the link:

http://help.sap.com/saphelp_nw04s/helpdata/en/5f/7a343cd46acc68e10000000a114084/content.htm

You would have to create logon groups and define the load balancing strategy.

Regards,

Srikishan

[Former Member]

Hi Srikishan,

Thanks for reply.

We had created the logon group in SMLG and assigned application servers to it.Similarly in webdispatcher we had assigned the application servers to groups.

----

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+

| group name | #entries |

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+

!DIAG

4

!ALL

4

| CI_MAIN | 4 |

Regards,

D S Kumar