The only features that might be off limits would be vendor-specific protocols, such as Cisco’s HSRP (Hot Standby Routing Protocol) and EIGRP (Enhanced Interior Gateway Routing Protocol). However, Vyatta and other open-source routers do support OSPF (Open Shortest Path First), RIP (Routing Information Protocol), and BGP (Border Gateway Protocol), as well as VRRP (Virtual Routing Redundancy Protocol). Interleaving these routers with industry-standard commercial routers is generally a non-issue, as long as the protocols in use are open, such as OSPF and BGP. In fact, with large BGP requirements, the cost savings can be quite significant given that it takes a sizeable (and expensive) Cisco or Juniper router to handle large BGP routing tables.
Raw versus refined speed
Another facet of open-source routing is performance. In most cases, the use of highly optimized packet forwarding code and custom ASICs will outperform generalized networking software. However, given enough horsepower, that’s not the case. You’re likely to get better performance from a server-class system running dual-core CPUs than a Cisco router, even though the underlying code on the server might not be as heavily optimized. When planning a network that will terminate hundreds or thousands of VPNs at a central office, this is a very big deal indeed – especially with a Vyatta router coming in at around one-third of the cost of a Cisco 7200-series router.
Jim Rigas is the president of Zito Media, a company currently evaluating Vyatta routers for use in a new large-scale network. Zito Media is building a carrier network to serve small communities in northern Pennsylvania, and the routers will be located in each town or city to handle all the routing tasks. "We’re very interested in the BGP capabilities," Rigas says, "since that’s an important part of the network we’re building."
The potential cost savings is the big draw, and here Rigas is taking the long view. "We are believers in getting into something that rides the cost curve of standard CPUs, and doesn’t lock us into proprietary hardware," he says. "Particularly in an area like this, where we’re dealing with a smaller number of customers, the cost/performance ratio is very attractive."
When I was discussing the concepts of open-source routers with a few network admins recently, the first thing they jumped on was non-Ethernet routing. It’s simple to implement any system as an Ethernet router, because Ethernet NICs are commonplace. But there are only a few places in any infrastructure where Ethernet routing is required. After all, Layer 3 switches perform far better than routers at that task, and one of the main tenets of routing is to move packets between disparate media types, such as between an Ethernet LAN and a T1 circuit.
So where does that leave open-source routing? Well handled, as it turns out. There are several manufacturers that make TDM (Time Division Multiplexing) PCI interface cards. One of the most popular is Sangoma, which offers single, dual, and quad-port T1/E1 interfaces as well as T3 interfaces. With Vyatta’s code running on commodity hardware, these interfaces appear to the OS and can be used as ordinary Ethernet interfaces. The single-port T1 interface costs around $700, so it's not bargain basement, but it offers a viable alternative for edge routing needs.