Dynamic routing in Linux with Quagga

Zebra Scout

Article from ADMIN 12/2012

By Konstantin Agouros

Cisco and Juniper have implemented routing protocols to help your router find the optimum path. On Linux, you can use software like Quagga, with its Zebra daemon, to help automate this process.

Complex, redundant networks, such as the Internet, require different routing policies from those typically found on a LAN. Ideally, the routers will know all the paths that lead to the target, but configuring them manually can quickly become confusing and lead to mistakes.

Quagga: Zebra for Admins

On the Internet, any attempt to do this manually would simply be impossible. The solution is to distribute dynamically changing route information automatically – including optional redundancies – if multiple paths lead to the goal. The web world has developed special routing protocols for this, usually only found on routers by Cisco or Juniper. However, Quagga [1] gives IT administrators the option of participating in the world's largest group of routers – with a Linux computer. The Quagga project originated with the Zebra Routing Daemon by Japanese developer Kunihiro Ishiguro [2]. The software is included in all popular Linux distributions and also runs on Unix derivatives like Solaris and Free/Net/OpenBSD.

Quagga doesn't handle the routing (that is still the domain of the underlying operating system kernel); however, it does provide a number of routing protocols – Routing Information Protocol (RIP) [3], RIPng [4], Open Shortest Path First (OSPF) [5] [6], Border Gateway Protocol (BGP) [7], and Intermediate System to Intermediate System (IS-IS) [8] – and it modifies the kernel routing table on the routes it learns.

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