Linux Networking - VLANs & Multiple IP's

Login or Register for Dates, Times and to Reply

Thread Tools Search this Thread
# 1  
Linux Networking - VLANs & Multiple IP's

In a "typical" data centre environment (telco, financial services etc), would a Linux OS typically have one IP address connected to one VLAN or would it have many IPs and/or VLANs. I say "Linux OS" as I'm referring to an instance of the OS not necessarily a Host or server. Think Linux OS = VM in a virtualisation context. Its common for a server/host to have many IP's and possibly in different VLANs but would an OS (VM) within that host typically just have one IP in one VLAN?

I'm asking because of an ongoing debate with a Network team that wants different IP's and VLANs per Linux OS and have us put for example ssh onto one IP, and then server traffic (e.g. HTTP) onto another IP in order to separate traffic. Is this kind of thing common in a modern data centre or not? When would one go that approach vs just putting the OS onto the VLAN thats "most representative" of its function: E.g. web proxy in DMZ VLAN, App server in Backend VLAN etc etc.
# 2  
Lots of views but no replies. Anyone?
# 3  

I'm currently working in a high security environment, here we have a kind of hybrid setup - where we have seperate Vlans for some functions and not for others.

By way of explanation I'll give a couple of examples.

All access to Consoles, Hypervisors, ILOM and things like management consoles are on a seperate Vlan. In addition all the SAM management is on an other Vlan and all backup on yet an other Vlan. The final segregated Vlan covers other administration functions - normally where people would want to ssh onto a server for things like Oracle administration.

However from the user interface perspective we have a large address range which is spanned onto a seperate Vlan which covers VOIP and applications access from the front end.


# 4  
Thanks Dave,

I can understand how the ILOM, SAN etc would be on different VLANs. In your case, does the VM OS itself span VLANs. E.g. if its a web server listening on port 80, would the web server IP be on one VLAN, and then an IP for SSH be on another VLAN?
# 5  
I can confirm such usage, mostly in virtualized environments.
Vlan tagging and if wanted etherchannel with vlan tagging.

It is a common practice mostly and i would recommend implementing it on any new hypervisors deployments.
# 6  

No doubt that a physical server and hence base hypervisor would connect to multiple VLANs and do VLAN tagging (e.g. in VMWare distributed switch). E.g. vMotion on one VLAN, VMWare admin on another, iSCSI on another etc.

What I'm referring to is the actual individual VM's inside the hypervisor. How many VLANs would they be connected to?

---------- Post updated at 12:23 PM ---------- Previous update was at 12:17 PM ----------

Here is an example picture :


See how each individual virtual machine is connected to only one VLAN, even though the physical host is connected to many VLANS. VM1 could connect to VLAN1, VM2 to VLAN2, VM3 to VLAN2 etc. What about a scenario where VM4 connects to VLAN 1 and VLAN2? I have never once found a picture nor seen an actual environment where a virtual machine has lines going to two different VLANs. Under what circumstances would it be necessary for a a virtual machine to go to 2 different VLANs?
# 7  
For instance, if you want make backup over dedicated network ?

In that scenario you would have one public network and one backup network in different subnets.
Cluster interconnects also, you can use seperate vlans for that, which would mean that there are now total of three separate interfaces on that virtual machine.

Hope that helps
Login or Register for Dates, Times and to Reply

Previous Thread | Next Thread
Thread Tools Search this Thread
Search this Thread:
Advanced Search

Test Your Knowledge in Computers #119
Difficulty: Easy
The Single UNIX Specification (SUS) is a standard for Unix systems to qualify and have permission to use the UNIX certification mark.
True or False?

10 More Discussions You Might Find Interesting

1. UNIX and Linux Applications

Xalan & Xerces issues for Oracle Linux 6.6 & Solarisstudio12.3 C++ compiler for Linux

Hi Team, I am facing issue while using Xalan & Xerces for my application. Below are my environment details i am using :- Platform:- Oracle Linux 6.6 Compiler :- solarisstudio12.3 C++ compiler for Linux Below are the versions of Xalan & Xerces source code used to build the shared object... (0 Replies)
Discussion started by: agrachirag
0 Replies

2. Linux

Linux networking configuration

I have a question concerning default gateways in RHEL. In Linux, the default gateway does not have to be associated with a specific interface - when you look at your routing table with route -n, your default gateway can be associated with the default route on the last line, and doesn't have to be... (0 Replies)
Discussion started by: rojizo
0 Replies

3. What is on Your Mind?

Career in Networking & Network Security

Hii i want to make career in networking and i m new in this field could u plz help me what should i do (2 Replies)
Discussion started by: pawan_kumar
2 Replies

4. Solaris

Networking with Hub, & Sol 10 Problem

Unable to Ping network nodes Currently have two Solaris 10 servers connected via a dumb Hub. I'm unable to ping either box but they can ping themselves. I have double checked physical connections and the following files; /etc/hosts - verified that all devices are listed correctly... (4 Replies)
Discussion started by: pham
4 Replies

5. UNIX for Dummies Questions & Answers

Networking unix & windows

I have very basic question: I have 2 windows sytem & 1 Unix system & wanted to put all three system into one network to each other. what kind of other hardware I need? like cable , router? can anybody tell me the configuration? like how to connect to external hardware to put into network? ... (9 Replies)
Discussion started by: kar1
9 Replies

6. IP Networking

Networking XP with Linux (Vector Linux)

I need help. I have a cable modem. It has an USB out. I didn't want to buy a router. So I hooked my WinXP computer up to the cable modem by USB. I wanted to network my Linux computer to the WinXp computer by the ethernet cards in each. The only problem is, I don't know what I need to know to do... (1 Reply)
Discussion started by: garfunkle
1 Replies

7. UNIX for Advanced & Expert Users

Linux networking

hi, we've linux suse version 7 and i've installed linux on the PC's, so could anyone tell me that which files should i change under /etc to be able to Telnet & Ftp to other machine? Rgrds, Nikk (3 Replies)
Discussion started by: nikk
3 Replies

8. Programming

networking aspect of linux

Hi, everybody. I wanted to know the networking aspect of Linux i.e how Linux works using networks. If anyone knows it or the site or book where I can find this topic then please inform me. Thanks a lot for your co-operation. (1 Reply)
Discussion started by: kinnaree
1 Replies

9. UNIX for Dummies Questions & Answers

Nescape & dial up networking "Linux"

Sorry I need to Know How to connect to the Internet using Netscape in the GUI of the Red Hat Linux .....using phone line with a modem Us robbitics ....Such as in windows We add dial up adapter etc ......:confused: (1 Reply)
Discussion started by: atiato
1 Replies

10. UNIX for Dummies Questions & Answers

Networking Problems On Linux

Discussion started by: IMOTEB
1 Replies

Featured Tech Videos