Hackosis

Times are getting thin before replacing the Cisco 7500 core router with open source routing platform, Vyatta, as mentioned in a previous post. And not only that, but the decision has been made to go ahead and set up redundant, auto-failover Vyatta routers. Also, check out how to throttle bandwith with the Linux kernel in Vyatta (or any other Linux with 2.4+ kernel) before I go into more detail.

The Hardware

The hardware has been purchased and received. The setup includes 2 - Dell PowerEdge SC1430s with the following specifications:

• 2 Quad-core 2.0GHz Xeon Processors
• 4 GB of 667MHz RAM
• 2 80GB SATA 3GB/s configured with RAID 1
• 1 Gbit Onboard NIC
• 1 Intel 1000PT Gbit PCI Express NIC

You couldn’t ask for an easier install with Vyatta and it did so beautifully with this hardware. Vyatta acually certifies Dell 850s and 860s. Seriously, the install procedure with the live CD is as simple as logging in as root, typing

install-system

and answering a few very basic questions. All hardware components were detected including the SAS 5IR Dell RAID PCI Express adapter.

The Software

Everything has yet to be setup; it is still a work in progress. BUT these are my plans. There will be a post after the system is up and running about how well everything listed here works.

NOTE: The following assumes you have already setup your ‘real’ IP addresses and static routes.

Automatic IP failover with VRRP

VRRP will be implemented for automatic IP address failover in the event that the primary unit goes down. VRRP involves setting ‘real’ IP addresses on the ethernet interfaces which will not function as the main routing addresses — just a way to access the machine through the network. After setting up VRRP the 2 (or more) routers share a VIP (virtual IP) that is managed by the VRRP process on each router. The backup router is constantly checking to make sure the primary router is up, if not, it takes over as the master router. Pretty cool, huh?

Example of VRRP Vyatta configuration steps (taken from the Vyatta Configuration Guide - 3.4MB PDF):

Router 1:

Router 2:

Easy enough to configure. Understanding the whole VRRP process is another story, but luckily Vyatta takes care of configuring VRRP for us when we give it the necessary information.

Route Propagation with eBGP

I chose eBGP over iBGP, since I am not looking for huge scalability and it is slightly easier to configure than iBGP. BGP stands for Border Gateway Protocol and is used to exchange routing information between peers. This will keep the routing information up to date between my redundant Vyatta routers without having to change the routing tables in both machines. In turn, if my primary router fails and the secondary router takes over through VRRP, it will have the most up to date routing information. BGP will have to be setup on the ‘real’ IP addresses and not through the VRRP in order to function correctly.

Example of eBGP Vyatta configuration steps (taken from the Vyatta Configuration Guide - 3.4MB PDF):

Router 1:

Router 2:

You can then verify that the eBGP is communicating with the following command:

I am confident BGP will serve well, it is the most used dynamic routing protocol on the internet today.

And there we have redundant routers via VRRP and eBGP with bandwidth control. I plan on setting up a cron job to copy the tc configuration through a SCP command every hour and emailing on failure (another post, another time). I hope you think about Vyatta as a possible solution for replacing proprietary equipment in your infrastructure. I will give you an update on how this theory works after the solution has been implemented. Feel free to share any routing tips and tricks in the comments, Vyatta related, or not.

Related Posts

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• An Open Letter To Vyatta — Vyatta (VC3) Cannot Replace My Cisco Router

Tags: Featured, Linux, Networking, Open source, Tutorial, Vyatta

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