Archive for the ‘Networking’ Category

Linksys PLK300 – Failed attempt to be lazy

Tuesday, December 2nd, 2008

These days pretty much every home theater device has a wired Ethernet port. In my case there is a Xbox 360, a PS3, and a Panasonic Plasma TV that all need to be connected to the home network. Sure wireless has come a long way but nothing beats Cat6 for that delicious low latency/high throughput satisfaction.

Powerline networking is not a new technology, in fact home automation companies have been using it for years for things like turning lights on and off and security systems. Recently electronics manufacturers along with networking giants such as Cisco have formed an industry alliance "HomePlug", with the goal of pushing this technology out of the ‘obscure home automation catalog’ segment into the mainstream home segment.

HomePlug 1.0 is this alliance’s first "ratified standard" for this new version of an old technology. This technology is sold in kits and separate adapters, and promise different theoretical throughput levels (From 85Mbps to 200Mbps). Devices from Linksys/Cisco, NetGear, and Belkin (among countless others) have begun springing up all over the brick and mortar electronic retailers such as Best Buy within the last few months.

My experience with the Linksys PLK300 was a pleasant one. The Linksys PLK300 is a 200Mbps kit with one single port adapter and one four port adapter. It comes with everything you need to get started including Cat5 cables and stands for the adapters. Installation was a breeze and took less than 5 minutes. I connected the single port adapter to one of the outlets in my home office (cough: video game den…) and the four port adapter to an outlet near my home theater.

Using iperf (which is widely seen as one of the best tools to test throughput) I was able to achieve the following results.

image

As you can see the throughput achieved through the PLS 300 installation was actually worse than my current 802.11G Network (I didn’t think that was possible). I never considered it even remotely possible that I would achieve 200Mbps through this system, but less than 18% of the stated max throughput is a little silly. I will note that while the throughput of the connection was considerably lower, the latency was much better on the HomePlug connection versus the Wireless (802.11G) and did not vary as widely.

I contacted Linksys to see if perhaps there was something I was doing wrong. (The system is fairly foolproof but they’re making new fools every day…) I was told that perhaps the wiring in my built in 2003 home was too old or of poor quality and that I should be getting much more than 11.3Mbps (avg). I asked if there was some software or a way that I could see what "rate" the unit is connected at and the technical support representative indicated that this was not possible.

So it says on the outside of the box that the unit will do up to 200Mbps but there is no way of knowing what speed the unit is "linked" at? It seems like either they intentionally omitted including a "speed indicator" on the units themselves so that you won’t know what speed you’re getting unless you’re anal (like me) and test it.

It could also be that there is no sustained connection speed and that it constantly varies (like wireless). Still, it would be nice to know what level of quality the signal between the two devices is.

Ultimately, I decided to return my units as I found that the cost wasn’t worth the performance but I urge anyone who is in a similar situation that I am in to give these units a try. Linksys is one of the best home networking companies around, and it is very possible that the wiring in my McCondo is to blame for the throughput issues.

If you have a similar or different experience with these particular units, please note that in the comments.

PLK300

Layer 4-7 Load Balancing using Foundry ServerIron XL

Tuesday, August 8th, 2006

If you’re like me, you use some sort of content switching device in your organization; whether it is a dedicated network appliance such as the Foundry ServerIron, or simply a module in a Cisco switch similar to the CSM. Often times, I find myself “firing and forgetting” about these units until it comes time to deploy a new one. Recently, I was charged with the task of implementing an 8 port Foundry ServerIron XL with Layer3 software, previous to this I had only worked with the older Layer2 models. This article attempts to explain the basic steps to achieve load balancing glory, using one of these devices.

Firstly, I noticed some fairly stark differences between the ServerIron XL, and the older model. One of the large changes is that it will no longer respond on its management port unless you have ip forwarding enabled. (From the router the loadbalancer is connected to, you can ping the load balancer, but from beyond that point, you cannot) This threw me for a slight loop as in the past all of my Foundry work has been Layer2 and worked perfectly.

The answer to this specific problem was the Virtual Interfaces command set, which assigns an IP address to the ‘default’ VLAN (usually VLAN 1) which then routes all IP addresses through that single point. This has the downside of utilizing an extra IP if you are working in public IP space (which I often do).

I will note that one of the nice things about the Foundry load balancer solutions is that you can have a Layer3 switch in between the load balancer and the servers you’re balancing, and my configuration is setup to do this.

Here is the entire configuration file:

ServerIron#sh run
Current configuration:
!
ver 07.3.05cT12
global-protocol-vlan
!
!
server predictor round-robin
!
!
!
!
!
!
!
!
!
!
!
!
!
server real app1 10.1.1.2
port http
port http url “HEAD /”
!
server real app2 10.1.2.2
port http
port http url “HEAD /”
!
server real app3 10.1.3.2
port http
port http url “HEAD /”
!
!
server virtual VIP 192.168.0.5
port http
bind http app1 http app2 http app3 http
!

!

!
vlan 1 name DEFAULT-VLAN by port
router-interface ve 1
!
enable telnet authentication
enable telnet password …..
enable super-user-password …..
ip forward
ip address 192.168.0.3 255.255.255.0
ip default-gateway 192.168.0.1
username admin privilege 5 password …..
password-change any
interface e 1
no cache-group
no spanning-tree
!
interface e 2
no cache-group
no spanning-tree
!
interface ve 1
ip address 192.168.0.4 255.255.255.0
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
end

As you can see, the ServerIron XL and all of the real servers actually exist on seperate networks; they are seperated by a Watch Guard X500 security appliance. On my router I have a vlan setup for 192.168.0.1 255.255.255.0 which is the gateway for the ServerIron XL, then I have static routes from the router, to the Firebox X500 and the ServerIron XL for 10.1.1.0/29, 10.1.2.0/29, and 10.1.3.0/29.

I will highlight certain parts of the configuration:

#server predictor round-robin

This command tells the load balancer to use round robin as the method of balancing connections.

#server real 10.1.x.x
#port http
#port http url “HEAD /”

These commands tell the load balancer which servers actually have the HTTP content on it.

#server virtual VIP 192.168.0.5
#port http
#bind http app1 http app2 http app3 http

This command creates a VIRTUAL server, which is where you would point your client browsers in order to access the round robin configured load balancing.

#vlan 1 name DEFAULT-VLAN by port
# router-interface ve 1

By default all ports on the ServerIron XL are assigned to port 1, this command allows the switch to use ve1 to access the ‘default-gateway’.

#ip forward

Enables IP forwarding, so that the load balancer can access the outside world.

#ip address 192.168.0.3 255.255.255.0

This is the management IP of the ServerIron XL

#ip default-gateway 192.168.0.1

This is the default gateway of the ServerIron XL

#interface ve 1
# ip address 192.168.0.4 255.255.255.0

This command assigns an IP address to the virtual interface Ve1 which allows the ServerIron XL to create static routes to reach the default-gateway.

The above configuration is very short, and is just an example of how quick and easy it is to leverage these devices in order to provide Content Load balancing for your critical Web, or other sorts of applications.

I hope you find this guide useful.

-Drew

Quick and dirty load balancing using Extreme Networks switches

Monday, August 7th, 2006

This article explores how to achieve simple server load balancing using inexpensive and readily available extreme networks switches.

Most Extreme Networks switches are capable of server load balancing, and Extreme Networks switches are available for next to nothing on eBay. There is a very large limitation to server load balancing on Extreme switches however; they absolutely will not load balance if there is a layer3 switch between the switch and the servers (i.e. if you have a firewall in between the Extreme switch, and your servers…)

Keeping this limitation in mind, Extreme Networks offers a very robust set of server load balancing options similar to dedicated load balancing hardware (Foundry ServerIron/ServerIron XL)

Here is a brief summary of how to SLB on Extreme Networks switches.

Below is a list of commands, under there is a line by line

#Here we create the VLAN that your load balanced servers will reside in. We assume that your switches’s IP is 10.1.5.1, and that your servers are on ports 2-3

create vlan lbservers
conf lbservers ipaddress 10.1.5.1/29
conf lbservers add port 2 untag
conf lbservers add port 3 untag
enable ipf

#Create the Server load balancing pool and add the real servers.

create slb pool lbpool1 lb-method round-robin
configure slb pool lbpool1 add 10.1.5.2 80
configure slb pool lbpool1 add 10.1.5.3 80

#Create the virtual server, assign real server pool to virtual server

create slb vip lbvip1 pool lbpool1 mode translation 10.1.5.4 80

#Set the server load balancing type, enable server load balancing, enable ip forwarding.

conf lbservers slb-type server
enable slb
enable ipf

#Substitute gateway for the name of your VLAN which connects upstream

conf gateway slb-type client

#There you have it, a very simple server load balancing configuration for Extreme Networks switches.

Enjoy making your purple dinosaur do new tricks! (dance Barney dance!)

-Drew