• United States
by Barry Nance, Network World Lab Alliance

Peribit Networks’ SR-100 appliance

Jul 19, 20044 mins

Bandwidth boosting box boasts boffo benefits

Bandwidth boosting box boasts boffo benefits.

Adding Peribit Networks’ new SR-100 appliance to your WAN link is an excellent way to increase bandwidth without buying more capacity. Our recent test of the SR-100 showed the appliance scales upwards in amazingly flexible patterns, offers a high degree of reliability, and installs quickly and painlessly. These features earn the SR-100 a Clear Choice Award.

Imagine your network infrastructure as a fleet of trucks traveling across a major highway. While the cargo is important, these trucks are often nearly empty. Telco WAN link charges are the equivalent of highway tolls that can cost your company an arm and a leg.

How we did it

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WAN link compression devices such as the Peribit SR-100 let you reduce the number of trucks being sent yet deliver the same cargo to each destination. You spend less on both highway tolls and truck maintenance.

Frugal WAN usage

We installed a pair of SR-100s, in combination with up to four SR-50 appliances as compression subprocessors, on our lab’s six-segment Fast Ethernet network (see How we did it ).

The SR-100’s ability to quickly and thoroughly compress data at one end of a link and fluff it back up at the other (you buy Peribit devices in pairs and typically connect each one between a switch and a router) is impressive. We used FTP, server-based file copying of 1M-, 10M- and 50M-byte files, e-mail traffic and Web server accesses to test the SR-100’s performance. In each test, a pair of SR-100s typically increased WAN link bandwidth by a compression factor of 5.2, and it did so at wire speeds, without introducing delay (see Table 1, below).

Compression factors for different data types
Data type Compression factor
4k to 8k e-mail messages 7.2
Web pages 4.8
FTP and file copy operations 5.5

By themselves, SR-100s are formidable tools for increasing the amount of data a WAN link carries. For the sake of scalability, however, an SR-100 can attach to the WAN through other Peribit devices, such as the SR-50, which the SR-100 uses as compression subprocessors (Peribit calls them SR-100 clients). Moreover, Peribit says an SR-100 can connect to up to 2,000 other Peribit devices across as many WAN links and can handle network traffic at rates of up to 155M bit/sec. In our tests, we achieved aggregate throughput of 8.2M bit/sec through a T-1 link when we attached two SR-50 devices to each SR-100.

To our delight, the SR-100 has a path-optimization feature. When we established parallel T-1 and symmetrical DSL links between sites, we could configure the SR-100s to shunt low-priority e-mail through the less-expensive SDSL link and send other, business-critical traffic through the higher-cost T-1 link. Moreover, because both links were compressed, we could extend each link’s life span before upgrading its bandwidth.

Database transaction rates, with and without compression
Connection Transactions per second – no compression Transactions per second – SR-100-compressed
Fast Ethernet (baseline) 75
512 kb/s frame relay 0.4 1.4
T1 1.2 4.5
T3 36 78

Compressing file transfers and Web pages is one thing, but we also wanted to test business-application traffic. We replayed a Sniffer packet capture of SQL Server database transactions through a variety of WAN links to see how the SR-100 would fare. Not only did the SR-100 increase the effective WAN link bandwidth by a factor of 5.2, it also increased the database transaction rate (see Table 2, above).

Installation and documentation

Company: Peribit Networks Cost: SR-100C starts at $24,000; SR-100F starts at $26,500; Client SR-50 is $6,000. Pros: Excellent compression; reliable; scalable. Cons: Pricey in some configurations; minimal documentation.
The breakdown    

Performance 40% 

 Ease of use 20%  5
Scalability 20%  5
Documentation 10%  2
Installation 10%  4
Scoring Key: 5: Exceptional; 4: Very good; 3: Average; 2: Below average; 1: Consistently subpar

After installing the SR-100 by simply cabling it inline between a switch and router, configuring it was straightforward with Peribit’s management  console software. A quick-start booklet accompanies the device, and online documentation is clear and comprehensive. The device even reverts automatically and smartly to pass-through mode (no compression) if it suffers an internal fault or power failure.

The SR-100 seems a bit pricey in some configurations, such as linking many slow-speed frame relay  lines to a central LAN. On the other hand, in other configurations, such as multiple T-3 lines, the SR-100 seems downright inexpensive. An SR-100C starts at $24,000, while the SR-100F starts at $26,500. Client SR-50s cost $6,000.

Until the telcos drastically reduce frame relay and leased line prices, the SR-100 is a nifty way to make your telco carry more of your data at a lower cost. It lets you defer buying more bandwidth or, for some WAN links, actually reduce the bandwidth you’re paying for.