Installing multiple webdispatchers on same server

[Former Member]

We want to install multiple SAP Webdispatchers 7.0 on same server using different ports. These webdispatchers connect to various ABAP and Java systems on same and different hosts. We also want to configure SSL on webdispatchers. Would there be any issues with this kind of setup. Would J2EE session cookies overwrite each other ?

[stefan_hainer]

Hi Venkata,

in principle it is no problem to run several Web Dispatchers on one host using different ports.

Only the cookies could be a problem if the clients connect to the different Web Dispatchers using the same host name and IP address.

I suggest to use different IP addresses and host names instead, so the clients do not have to enter different ports but host names (which is quite easyer) and you do not get in trouble with the session cookies.

Regards,

Stefan

[Former Member]

We have a similar situation. There is a existing webdispatcher for SRM however now we want to build one for CRM and planning to use the same host but different port.

So far I have installed it in DEV in such a way that SRM webdispatcher has a different owner e.g. 'srmadm' and CRM has a different owner 'crmadm'. The webdispatcher profiles owned by srmadm has port 8663 and the credential cred_v2/pse owner is ONLY srmadm AND profiles owned by crmadm has port 8643, credential cred_v2/pse owner is ONLY crmadm.

Is this type of solution really supported?

[Former Member]

Hi Stefan,

We have installed 4 wd on the same box to try and also on different m/c to test the father/child dispatcher. But the issue which we get is the page not refreshing the 1st time.

For eg,

A <-- B

<--E ( the father dispatcher,which we tried from the DMZ side as well all the instance on the same system)

C<--D

While accessing through A, B, C, D everything works fine, but only when through E, it does not at the first time, we need to refresh and then logs in.

Could you please let me know what could be the issue?

Regards

Prash

[Former Member]

It is possible to install multiply WD on one server since you can have each WD instance have separte port # and instance numbers.

The real questions is why would you want to? A WD is a software load balancing program running of a physical server with CPU/memory limitations. If you have multiply SAP instances (ie. ECC, CRM, and SRM), I would suggest you install the WD on the CI of the respective SAP instance.

Otherwise, regardless that each WD has different ports, its still a single connection to the phyical server with multiply connections coming through, which, in a high load situation, the phyical server that host the WD would not perform very well, compared to a HW load balancer or installing the WD on separate hosts.

Just some thought.

[Oliver5]

Hi,

Hi can install multiple web dispatcher on one host (with different SIDs)

Note: until release 7.20 (same kernel/web dispatcher also in 7.02) you need 1 wd per message server. It is also possible to cascade them. see note:

[https://service.sap.com/sap/support/notes/740234|https://service.sap.com/sap/support/notes/740234]

[Former Member]

Thanks for the reply. We cannot cascade the webdispatchers since we don't have path's with different prefix.

"Hi can install multiple eds on one host (with different SIDs)" - Does eds mean webdispatcher's ?

In the below pdf, it is said that Installing of multiple webdispatchers on same host with different TCP Ports is not recommended since it may overwrite J2EE session cookies. Is this only valid for webdispatcher release 6.20 ?

https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/com.sap.km.cm.docs/library/events/webinars-nw...

[Oliver5]

hi,

(eds means WDs. sorry i corrected it).

I think the statement of the slide is ok for external facing Internet multiple AS system setups on one host. Do you plan this?

However the mandatory rule is ONE webdispatcher per ONE message server until 7.02/7.20 (exception: dual stack setup with Java addin, which is not not recommended anymore by SAP except for Solution Manager. This setup has one MS for ABAP and one for Java typically. In that case use/count the ABAP message server for WD only).

Means in your case that you have multiple NetWevaer AS Systems on ONE host with ONE IP adress (if your OS handles only one IP adress). Then you have to cascade in my opinion. 1 WD for the internet with the internet standard port forwarding to the "2-n" other WDs with differing ports. This is then also helpful for security reasons. However I am not a 100% sure, because I never setup such a configuration myself.

[Former Member]

Thanks for your reply. Our scenario is we want to install multiple webdispatchers (different instances) on one single host which connects to backend systems. Some of the backend systems are on same host and some of them are on different hosts. Can we do this without having virtual IP addresses on the webdispatcher ?

[Oliver5]

I would say yes.

Web Dispatcher connects always to a to client as to server with a defined port. IP Number:Port is different for each web dispatcher and each connected server.

If you have only one ip:port for the internet, but several web dispacthers, becasue you have several system with several central systems/ message server, then you have to cascade the Webdispatcher. One Web Dspatcher collects all others WDs for the internet IP:port.

Virtual IP adresses is IMHO more relevant for high availability and/or ACC adaptive computing controlling if you want to move Systems to different physical hosts.

BR, Oliver