Seperate SAP-Net for TCP/IP Traffic between LPARs ?

[Former Member]

Hello together,

I want to make a seperate IP-Net on a seperate ethernet-interface for the IP Traffic between the LPARs to give more bandwidth to the IP-connections.

Normal you have a extra server IP-segment, for example 10.10.10.xx. This IPs will be routed to the gateway and to the clients. If you have an application-server in front of the iSeries, you will have an seperate IP-net 10.10.11.xx, which is layed on a seperate ethernet-interface, so that you can be shure the the IP-traffic is not going over the ethernet interface, which is used to serve the SAP GUI clients.

Our idea is to make a special IP-net for the LPARs itself. For the traffic which is going from R3-LPAR to BW-LPAR or GTS-LPAR. We would like to set this IP-net (for example 10.10.12.xxx) on seperate ethernet-addapters, which are connected to a dedicated switch. For this we probably need to configure some sm59 entries new and perhaps some other things too.

So my main questions are:

Is this a good idea?

Is the performance really improved?

Do we have after doing this more problems with other things?

Is there anyone out who has tried this before?

best regards,

Carsten Schulz

Germany

[Former Member · Accepted solution]

We did something like this.

We call it the "virtual lan".

We set up a TCP/IP interface under CFGTCP option 1 (Work with TCP/IP interfaces) and associated that with an appropropriate line description. We associated a host name with the IP address using CFGTCP option 10 (Work with TCP/IP host table entries).

It is faster, though I don't have specific stats. The speed of the virtual lan is 1G unlike the external ethernet which is 100M, so that is quite a difference. The traffic between systems is not in contention with everything else, which makes a difference if you are doing a lot of extracts from R3 into BW and things like that.

Another nice thing about it is that it stays up even if your routers go down, since the virtual lan is all internal to the iSeries.

Good luck

Brian

[Former Member · Accepted solution]

Hi Brain,

thanks a lot for your answer.

The last sentecne from you is an interessting point.

You wrote that you have associated the IP-Adress to a appropriate line description. If we create a normal line description, it will be conncected to a real etrhernet-adapter. What is the specific definition of the line-descition which you are using to connect the LPARs together. Why do you think is the IP traffic not going out of the box ??

best regards,

Carsten Schulz

Germany

[Former Member · Accepted solution]

The virtual ethernet is provided as a special feature of LPAR which allows the kind of communication that I noted.

IBM has information on the features of virtual ethernet and what you need to do:

<a href="http://publib.boulder.ibm.com/infocenter/systems/scope/hw/index.jsp?topic=/iphat/iphatvirtualetherneti5os.htm">Virtual Ethernet for i5/OS logical partitions</a>

<a href="http://publib.boulder.ibm.com/infocenter/systems/scope/hw/index.jsp?topic=/iphat/iphblconfigvirtethp6.htm">Configuring a virtual Ethernet adapter using version 7 or later of the HMC</a>

<a href="http://publib.boulder.ibm.com/infocenter/systems/scope/hw/index.jsp?topic=/iphbk/iphblconfigvirteth.htm">Configuring a virtual Ethernet adapter using version 6 or earlier of the HMC</a>

You create a virtual ethernet resource using the HMC, and this is what is used for the connection. It is by virtue of using a virtual ethernet adapter, instead of a hardware adapter, that you get the 1G speed and the peer-to-peer nature of the connection, requiring no external router.

Good luck

Brian

Fix spelling

Message was edited by:

Brian Sammond

[Former Member]

This thread is very intriguing.

Does anyone have any links to information on how to configure the VLAN that they are willing to share?

How long did it take to set it up?

What steps do you take to move your trans directory between partitions?

Thanks in advance for any insight/assistance.

Robert

[Former Member]

Hi Robert,

have a look to the links in this Diskussion above, or have a look to this book

http://www.redbooks.ibm.com/abstracts/sg247491.html

<b>Chapter 9 "Vitual I/O"</b>

best regards,

Carsten Schulz

Germany

There are 10 types of people in the world: Those who understand binary, and those who don't.

[Former Member]

Hi together,

ok, I see this will be a philosophic question. )

There is the second question from me. Is there anything in SAP to to use this new connection?

best regards,

Carsten Schulz

[Former Member]

Hi Carsten,

We use it for the QFilsvr in AS400 to mount the "trans" directory from one system to the other...and it really works great...

This dedicated "VLAN" is 1GB and the speed is phenomenal...and you can notice that when you are importing support packs from EPS/in mounted on remote system..It "almost" takes the same time as having that on a local system..

I just finished doing an upgrade where the system having the local "trans" and one having a remote "trans'..took almost the same amonnt of time in SHADOW_IMPORT_INC....the stage where it imports the additional support packs from EPS/in......did not have to change a thing before the upgrade...

Same goes for support packs imports etc...

Thanks

Abhi

[Former Member]

Hi Abhi,

this seems to be good for the performance between LPARs on one System i.

How could I combine this good idea 'VLAN', with a net to 3 partitions on another System i ?

For example we have 6 partitions on two System i using one /usr/sap/trans in nearly all partitions. So we have to define more than one IP Interface. One Virtual in a System i and one extra espacially to the other partition with the /usr/sap/trans ...

Carsten

[Former Member]

Hi Carsten,

I am not a person with a deep knowledge of networks(my networks guys configured it..), but the way it works is we have two interfaces on each of the LPAR's/boxes...(our configuration is DEV/TEST as seperate LPAR's on one box and PROD on one box..we run i570's)

The high speed interface or the "VLAN" has a sepearte address as the other regular interface thru which the users access the systtem. )

Then on the LPAR/boxes, in the GO TCPADM menuoption 1>option 10--> u define the hostnames with the "high speed interface " IP address...instead of the the regular IP address...

Then on the LPAR/boxes, in the GO TCPADM menuoption 1>option 12, you make :

Host name search priority . . . *LOCAL ...

So now it first checks the local host table before going the domain server..

and hence picks up the fast interface...

Let me know, if you have any other questions...

thanks

abhi

[Former Member]

We did the same as Abhi with defining the host name as I mentioned in my earlier post, using CFGTCP.

In addition, we have *LOCAL as the Host Name Search Priority value same as Abhi.

You can get to this with GO CFGTCP option 12, bypassing the TCPADM menu. Or if you prefer the command line, the CL command is CHGTCPDMN, prompt it.

Good luck

Brian

[Former Member]

Hi Carsten,

at least you will NOT measure a noticable performance difference.

I guess, you are doing this for your necessary Windoows APPL server. The "improvable" performance here is normal and is lying somewhere else.

=> You can do so, but the Win Appl server will not be really faster afterwards ;-(

Regards

Volker Gueldenpfennig, consolut international ag

http://www.consolut.de - http://www.4soi.de - http://www.easymarketplace.de

[Former Member]

Hi Volker,

ok. I thought the same about the performance.

But we dont want to speed up the Windows Applications Server.

We want to split the IP traffic, which is going from one LPAR to another, from the IP-traffic to the SAP-GUI clients.

And the question was: Do I realise this in practice? Or is it only more work from the network administrator?

best regards,

Carsten Schulz

[Former Member]

I think Volker may just be giving you a standard caveat.

Is the 1G speed faster than your existing ethernet?

Will reducing traffic on the existing ethernet reduce collisions?

Is eliminating exposure to network outages worthwhile?

IBM has this to say in the following link:

<a href="http://publib.boulder.ibm.com/infocenter/systems/scope/hw/index.jsp?topic=/rzai2/rzai2virtethconsider.htm">Virtual Ethernet considerations</a>

<i>[Some features of virtual ethernet include]

Fast: The virtual Ethernet emulates a 1 GB Ethernet connection and provides a fast and convenient communication method between partitions. This enhances the opportunity to integrate separate applications that run on different logical partitions.

Reduced congestion: By using the virtual Ethernet for interpartition communication, communication traffic is reduced on the external LAN. In the case of Ethernet, which is a collision-based standard, this will certainly help prevent a degradation of service for other LAN users. </i>

It would be hard to argue that you <i>wouldn't</i> benefit from this.

Apart from the initial setup, there is no appreciable impact on a network administrator's job.

The virtual ethernet comes online at IPL; there's really nothing to do.

Good luck

Brian

[Former Member]

Hi Carsten,

it depends ... some customers do have that and some not ...

From performance point of view, it is not really an issue today, but sometimes this is wanted for "organizational" or security reasons ...

... at least SAP supports it and you will not have too much trouble with it

Regards

Volker Gueldenpfennig, consolut international ag

http://www.consolut.de - http://www.4soi.de - http://www.easymarketplace.de