Re: topologies

To: " users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: topologies
From: Gerry Reno <greno@xxxxxxxxxxx>
Date: Sat, 26 May 2007 21:38:31 -0400
Joseph Mack NA3T wrote:
On Sat, 26 May 2007, Gerry Reno wrote:

Joseph Mack NA3T wrote:

separate from what, the other realservers? the VIP?

then it's more difficult to administer them and also they will lose access to common resources such as the backup server. So it looks like each realserver will have to be part of multiple lans or vlans into order to still have access to common resouces. In doing so, will it create any problems with routing for the VIP's and GW's?

such as?

I don't want any triangulation problems that can cause connections to hang.

what's a triangulation problem?
where you have the response packets best-routed around the director directly back to the client

OK you want LVS-NAT or the modified-shared version of LVS-DR (if you don't know what that is, use LVS-NAT).

Ok, some ascii art:

you need blanks and not tabs, and limit to (about) 50chars/line

|(Single Public IP)
| HW NAT Firewall |
| Router |
| ==LVS== | | | |( |( | |(192.168.0.nnn)
--------------------- --------------------- | ---------------------
| keepalived | | keepalived | | | lots of other | | master | | backup | | | servers |
--------------------- --------------------- | ---------------------
|(GW= | |
------------------------------------------------------------------- |
| | | | |
|( |( |( |( |
--------------- --------------- --------------- --------------- |
| RS(web) | | RS(web) | | RS(db) | | RS(db) | |
--------------- --------------- --------------- --------------- |
|( |( |( |( |
| | | | |
--------------------- |
| Network |---------------------------------
| Storage |(

This is what I was referring to when I was commenting on topology and if it is possible to configure this way I was concerned about packets being best-routed somehow past the director through the second interface on the realservers.

taking a punt here...

you have director(s) with a public IP (here Then you have some web realservers, on Presumably these talk to the db machines (and the clients do not directly connect to the db machined). In which case the db machines can also be on And you have a NAS which can also be on
This was part of my problem. All the other (non-LVS) servers on the network are on 192.168.0.nnn which includes the NAS server. If I put NAS on the network it may be a problem. Maybe I can use /23 to keep it visible on both networks. But again I still am concerned about packets finding their way directly back to 192.168.0.x network and to the client.

The webservers will have as their default gw. The other machines (db, NAS) shouldn't havea default gw at all (presumably they aren't replying to clients)
Hmm... I still have other LVS services like SSH that I want to make available on these machines. I'll have to think about this part some more.



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