Visual UpTime 5.0 and DS3 ATM ASE: Premier Service-Level Management
May 17, 1999
By David Willis
With the growing number of large frame relay installations now using ATM to consolidate traffic at their highest density sites, service-level management on ATM is paramount. Using the same genius found in its earlier products, Visual Networks has brought its highly successful frame relay service-level management system into the ATM arena with a new release of its Visual UpTime software and DS3 ATM ASE hardware device.
I tested beta versions of both Visual UpTime 5.0 and the DS3 ATM ASE in MCI WorldCom Developer's Lab in Richardson, Texas, and was delighted with the quality of information these products provided in a mixed frame relay and ATM network. Since the last time we tested UpTime (see "Lifting The Fog With Frame Relay Management Products," www.networkcomputing. com/911/911rl.html), Visual has enhanced its analysis to provide more manager-level reporting. It is now unquestionably the premier frame relay-specific service-level tool. Once Visual aligns the ATM products with its frame relay capabilities, the company may well own ATM WAN service-level management, too.
A focused WAN management application, Visual UpTime measures and reports the most important aspects of frame relay and ATM service--availability, data delivery, delay and utilization. Like many network management systems, it includes an event manager and exhibits protocol analysis capabilities. In my lab tests, the software expertly displayed circuit-level details, but its real strengths lie in its planning and reporting features. Visual UpTime's service-level, capacity-planning and circuit-level reporting features also are quite impressive.
During testing, Visual UpTime's Burst Advisor component helped in my analysis of utilization patterns. While it continues to recommend changes to the Frame Relay CIR (Committed Information Rate), it now also presents suggestions for its ATM analogue, SCR (Sustained Cell Rate). Although most views within UpTime are on a circuit-by-circuit basis, including Burst Advisor's, the Executive Burst Advisor provides a networkwide view of the most- and least-used circuits in the WAN.
Sweating the Details The Visual system collects data using proprietary probes--called Analysis Service Elements (ASEs), in Visual parlance--that are built into a passive monitoring device or CSU/DSU. Data is then fed at least every two days to a database maintained at the PAM (Performance Archive Manager), which is a Windows NT server running Visual's SQL server-based database. Frequently, carriers maintain PAMs as part of their own managed-service offering, letting customers manage the network from their own client workstations.
Management information is accessible from a PAC (platform-applicable client) workstation running under Hewlett-Packard Co.'s HP-UX, IBM Corp.'s AIX, Microsoft's Windows 9x/NT or Sun Microsystems' Solaris. These clients have complete access to all functions of Visual UpTime, including network baselining and performance monitoring, troubleshooting with traffic capture and conversation analysis, and network planning and reporting. In addition, a Web client can access planning and reporting functions only.
Solving Problems My Visual UpTime test installation proved useful within the first hour. From the VC (Virtual Circuit) troubleshooting summary, I discovered that our ATM router was incorrectly shaping traffic, preventing cells from entering the network above the SCR of 75 cps (32 Kbps). The router should have allowed bursts to a PCR (Peak Cell Rate) of 3,622 cps (1.5 Mbps). After a few adjustments at the router, I was moving cells well above the SCR.
In my tests, UpTime correctly identified relative traffic loads of FTP, HTTP, SMTP and a randomly assigned TCP stream at the ATM ASE. Using the traffic capture mechanism, I used both pre- and post-capture filtering to correctly identify and decode this unknown stream. UpTime also helped me discover some physical layer outages and PVC instability--problems that weren't evident at the end points. Fortunately, UpTime's diagnostics helped catch these minor problems, so the carrier could address them before they became noticeable to users.
Visual's new DS-3 ATM ASE probe provides statistics on 1,500 PVCs (Permanent Virtual Circuits) per DS-3, differentiating traffic by ATM Adaptation Layer (currently, AAL1 and AAL5 only; AAL2 traffic is listed as "other"). Physical layer and OAM (operations, administration and maintenance) diagnostics are similar to those found in CSU/DSUs, such as loss of signal, alarm indication signal and severely errored seconds. Because the ASE masks some minor alarms (such as PLCP errors) from the router, you may need to adjust the type of troubleshooting you're planning to do at the router level.
The Missing Pieces Some frame relay-management features are not yet available in ATM. For example, you can't see protocol distribution on the ATM side. Visual's frame relay probes break out up to five protocols concurrently, identifying Layer 3 traffic and listing 13 of the most common IP applications. Users can also define custom IP ports for tracking purposes. According to Visual, plans for protocol-distribution analysis using ATM probes are in the works; this does not indicate a limitation in hardware, memory or its functional operating system. In addition, some thresholding capabilities are not available, and Visual has not implemented round-trip delay measurements, a hallmark of its frame relay tool set. All these features are expected to be added some time this year.
Surprisingly, this version of Visual UpTime still does not issue alarms based on frame relay-delay thresholds, even though delay may be periodically measured to feed the Planning and Reporting tool set. Other frame relay-management products deliver this capability, so it's odd that Visual UpTime doesn't. If you are running real-time services--voice and video--on your frame relay network, this function would alert you to potential problems before your users take notice. Like other frame relay management systems, Visual UpTime does not analyze voice traffic or provide any tracking and accounting of SVCs (Switched Virtual Circuits).
In a Nutshell Visual UpTime delivers real insight into one of the most data-intensive problems in WAN management--accurately measuring public carrier service levels. This product is one of the few network-management solutions that provides answers to crucial questions: Am I buying too much network for my traffic, and is my service provider delivering on its commitments? If your carrier is offering Visual UpTime, buy it. If it's not offering UpTime, and you have the budget to build it yourself, talk to Visual Networks.
Send your comments on this article to David Willis at dwillis@nwc.com.
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