The Linux Router

The performance of the Linux router makes it an attractive alternative when concerned with economizing.

The Linux router is very stable in its operation. We have run it for long periods, and it showed a very stable performance over the entire length of time. The graphs in Figures 5 and 6 show that the bandwidth of the Linux router is fairly constant with a great increase in the amount of data.

Figure 5. Effect of Increase in Data on Bandwidth of Linux Router

Figure 6. Variation in Bandwidth of LRP with Increasing Time

The write-protected medium for booting off the Linux router gives it increased security from crackers. Once booted, it runs exclusively off RAM. You may safely take your floppy out of the floppy drive and put it in a secure place until it's needed again. Also, a single floppy can be used to boot many identical Linux routers with a runtime change in configuration.

Easy to Handle

The Linux router is easy to handle and configure. It does not require any special care for its use other than that required for a normal PC. If there is a problem, configuring it only takes a few minutes. Moreover, it is basically software on a floppy disk; if your LRP box gets damaged because of power fluctuations (a common problem in the third world), you can instantly convert another available PC into your router by adding NICs from the corrupted LRP (if they are not corrupted) and boot it off the floppy disk. No configuration will be required for this router at all, except the runtime configuration. You can imagine what a great advantage this is—think of what would happen if your Cisco router were to be corrupted.

Comparison with a Commercial Router

The following is a comparison of the Linux router with the Cisco 2620 router available in our laboratory.

The cost of building a good Linux router (based on a Pentium I, 200MHz MMX) with 1FDD, 32MB of RAM is less than $100 US. (It may be nearly free if you use the minimum required hardware, i.e., a 486DX with 16MB RAM.) A monitor is not necessarily required. You can use a borrowed monitor temporarily at configuration time or configure via a remote serial connection (if you include support for that through the serial.lrp package). On the other hand, the cost of the Cisco 2620 with a 50MHz Motorola Processor, 16MB Flash RAM and 40MB DRAM is more than $3,500 US.

Although power consumption here is not of great concern, in most applications it is notable that the Linux router (running on PI 200MHz, MMX) consumes less than 30W of power, while Cisco 2600 series routers consume 75W.

You can add as many NICs in the Linux router as you wish (limited by the number of slots on the main board). In Cisco 2600 there is only one Fast Ethernet card available.

The modularity of the Linux router is matchless. Its packaging system allows easy removal and addition of features. You can add/remove packages, even at runtime, using the lrpkg command. You need to shut down the Linux router to add a module only if it requires some additional hardware. However, the kernel module for the hardware can be installed at runtime using insmod. The design of the Cisco router is not as modular.

For the Linux router there are a large variety of hardware and software products available in the open market as it has the complete structure of the ordinary Linux operating system. You can use the product of any manufacturer that has support for the Linux router. Cisco routers, on the other hand, are limited in this respect. Usually only Cisco products are used with Cisco routers.

Having Linux as the operating system on your router gives you the extra advantage that you can build your own packages according to your needs using shell scripting. You also can get a lot of help from the available literature for Linux. Cisco routers have their own specific operating system called Internet Operating System. The Cisco 2620 uses IOS release 12.1. Although it is developed on a regular basis, you can use only those features that are available in the specific IOS release used on your specific router.

Like Cisco routers, the Linux router also supports the multiprotocol feature. It has support for RIP, BGP, OSPF and many more that are added through packages.

Services such as Ethernet router, firewall, DNS and ISDN may be initialized on a Linux router. However, initializing services like DNS (which is highly CPU-bound) will degrade its performance. It is better to use a separate machine as a DNS server. The Cisco router has multiservice integration of voice, data and video. As with Cisco routers, IP masquerading, port translation, load balancing, transparent proxy and interface alias may all be implemented on a Linux router.

Cisco routers support IPX, Token Ring, VLAN, VPN, Apple Talk and DDR for advance routing. The Linux router also can support these features through proper packages. Although to do so, some expertise in Linux and some additional hardware are required, which will increase the cost of Linux router, but it still will be much less than that of a Cisco router.

Depending upon the model and series of the Cisco router, it has a limited number of WAN slots. In the 2620 there are two WIC (WAN Interface Cards) slots, one network module and one advance integrated mode slot. The two-port serial WAN card has a asynchronous speed of 115.2Kbps, and synchronous speed equals 2.048Mbps. Port 1 supports only synchronous mode. The Linux router also has support for WAN interface cards. Sangoma WICs (, which have a synchronous data rate of 8Mbps, are quite popular among LRP users. With these cards you can combine many LRP boxes. However, the disadvantage is that the cost of the LRP box increases—this card costs about $400 US.



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About Linux Router

golecha.dinesh's picture

I am doing my BE project in Linux router But I dont get the exact idea about it and various questions arises like
is this practicaly implemented?
this project having very small apllication area can you modify it?
is it more secure?
so can you goide me for solving my problems and if you have any innovation then please convey me on my mail or here..........
good day............

Using Linux Machine as a router

Vikas khatana's picture

I am planning to use linux machine as a router and want to terminate leased line connection on it.
Can anybody suggest me that how to terminate a leased line on a PC.
I have a leased line with a modem with V.35 cable.
I want to connect this modem with linux machine through V.35 cable.

The bandwidth test with

Blanc57 (France)'s picture

The bandwidth test with different configuration is very interessant. It helped me a lot in trying to find the right configuration builfing a Linux Router. Thanks a lot for the work...

Linux Router

Sadiq Hussain's picture

I have been working on cisco routers and technology for last over 10 years and worked in Cisco Systems and recently developed interest in Linux and Linux routers. This article gave me lot of information that I needed to understand working of linux rotuers and I agree that some low cost alternative is needed to help ease and lower routing gear costs.

Try linux router from

Anonymous's picture

Try linux router from seems very interestedly.

Linux Routers

Keith Daniels's picture

Check out IPCop. A lot of things have changed since this article was written. It will show you what people are currently working on and give you an idea about how extensions (a al Firefox) can be used in a router system.

I set IPCop up to control the kids using p2p and locking me out of the internet by using all the bandwidth. I was impressed with what you could do with the software and how well the extensions worked.

Quite stable also.

All the new OSs and windowing systems are oriented towards content consumption instead of content production.

--Steve Daniels 2013

Linux Dual Routing+Fail Over+Control QoS

Lukas's picture

Hi, Im Lukas from Argentine. I use Linux servers for years, and this the best choice for manage network traffic and give services like Internet Connection to LAN, http web server, dns support, hosting, ssh remote conection, etc.

Now, i work in a Linux With Dual Routing or Most interfaces to the internet, but still having problems with the routes and packets.Any information is welcome.

This router offer many connections + ISP1 + ISP2 + ISP2, and fail over functions and control bandwith.

I'm networker Cisco butLinux is the best choice for an economize purpouse.

Thanks. Greetings.

Lukas (Mendoza - Argentina)

Can you tell me about OSPF support?

Anonymous's picture

I personally find the project impressive! The router as they test it can be up to the limits of the 90Mbps at the 100Mbps fast ethernet, and we naturally thing that the Linux box can also perform well with Gigabit Ethernet cards increasing the bandwidth of routing between LANs at a very high degree! The 8Mbps Wan slot(s) we can add is also just fantastic. But the big question is: What about with dynamic routing especially with OSPF (or RIPv2 / BGP)? The Linux router would be a just TREMENDUS solution when using those CPU intensive dynamic routing protocols. Commercial routers with just 50MHz processors and a little amount of RAM really suffer when using OSPF with large routing tables. I think that if the guys went that step forward then people would start construct the Linux router immediately! PPP / HDLC / Frame Relay etc. should have enough support on WAN interface too, and if they were add services such as DHCP then...the mirracle could really happen! :-) Well, I promise myself that I will construct the Linux router as soon as possible, in order to route connected networks first, but tell me please if you know about the OSPF module!!!

I used on practic Linux as

Pavel's picture

I used on practic Linux as router solution and it is perfect. I worked in Internet company where I used cisco routers and linux as routers. I had PII 800MHZ with 256M RAM. And perfomance of this router was perfect. it has 4 ethernets, many firewalls rulles and sniffer based on libpcap and postgreSQL server which collect IP traffic statistics. I have never feal that througput is lower then WAN router can support. In case of DoS somitemes cisco 2610 is dead, but Linux was alive and wrote logs. Ofcause it was hard to connect to it throught ssh ,but it was alive and responds.
Also I used BGP, OSPF on this router (used gated, zebra) with a big table (up to 200 routers in OSPF on P4 2GHz 512 RAM)
I had 4 WAN channels to router cisco 3640 and it was directly connected to the Linux router which was as bacbone router between WAN and my ISP network. It works as router, as traffic accouter and advanced firewall (kernel 2.4.20 with using utility of iptables and iproute2 package). What about policy routing? It works on Linux without problems!!! And sometimes it is more flexible then cisco.
I am cisco certified but anyway I love linux. I didnt run PRI/ISDN and HDLC WAN on linux, but it is possible. Therea meny project on Linux. - Linux with PCI Digium card - good replacement for cisco access server.
I tested Linux on real networks in Russia.
Now I am currently live in USA and many people here not understand strengths of Linux. microsoft and cisco for them is best way in IT, this is actually market influence.

How about the performance of NAT with P2P runnging ?

dtl mark's picture

Recently , i buy a linksys router , it performance is too....bad !
i have no $$$ to buy a cisco , so i thinking to make a Linux router with a old P-III 700 /w 256M RAM , i don't know the performance of this , P2P like BT , e2k , over 10,000 port open concurrent , can the p-iii reach the 100Mbps performance ?
i got a free 100BAST-T link form my ISP , yes! this is free !!! in fact 6 month test , i need to make report of performace to the isp serive every month , when i direct connect my pc to the isp link i got 70~86Mbps , but though the linksys router , it's drop to 50~60Mbps , it's not bad , sice , there have 40mbps+ , about 10 time faster than my 6M ADSL form other ISP , but when i rung p2p app , yes like bt , it's drop lower , lower ,and lower , than halt-up !!! , this $50 us router , just can't handle the high trsffic , this chep linksys router , i tested ,when i limited the concurrent port can be opened to 50 , the linksys will not halt.
but this will wasst the badnwith of the link ,
i just want to know , if the 700Mhz P-3 will work , i will but a old one to use at a router , if not , i will buy a ture router can habdel it ! , the price is $200 , well , 40 vs 200 , 5 time !

256 MB of RAM = more than 16,000 simultaneous connections

Anonymous's picture

With 256 MB of RAM you should be able to sustain a bit over 16,000 simultaneous connections by default, with tuning more, look at

And for an easy to use linux firewall try smoothwall

HTH HAND etc...

how to design linux router

saurabh's picture

can anybody sent me documentation on "how to design linux router".

Re: The Linux Router

Anonymous's picture

Also, lets give Mr. Dave Cinege some credit here. You could've at least mentioned his name in your article. Visit and read about his experiences and lack of acknowledgement throughout this projects history. I know I'm ranting here but DAMN IT CORPORATE AMERICA......GIVE BACK!

Re: The Linux Router

Anonymous's picture

Why? Why would anyone give credence to the insane embittered rantings of a physchotic. He had a great idea that he started, but then refused any offers of assistence to make the project more usable. His sole answer to questions in the support forums were read the code and call people stupid.

Then he declared a day of morning when Terry Nichols was executed. You remember him dont you Dave?
The mass murderer you viewed as a hero.

Are you still signing your name Dave 'kill a cop' Cinege?

Nichols was never executed. Y

Anonymous's picture

Nichols was never executed. You may have thought of McVeigh, but you went so far as search for the wrong guy on Wikipedia...or is this Dave so insane he called a day of mourning for someone still alive?

Re: The Linux Router

Anonymous's picture

Additionally, it would have been ideal if the cisco 2600 that was being referenced could have been tested in the mix of machines. e.g., 133, 200, 733 - to give a true "feel" for the overall performance of Linux Routers. I am silently cheering for Linux-but need direct indisputable evidence of performance as well as price and functionality. BTW: I think the layout of your work was fantastic - lets add the cisco device into the mix and retest!

Re: The Linux Router

Anonymous's picture

Has anyone done comparative tests with more than one flow of traffic?
What about traffic with the average packet size much smaller than 1500 bytes at the same level of bandwidth? It's usually the number of packets per second that will kill a router, not the throughput.
What about the number of different traffic flows, can it still cope with 50,000 traffic flows at the same throughput?

Linux is the cheap answer, but you have to remember, it's not always going to be the best, and it's not always going to perform adequately.