ISPPlanet Cache Review Series - NetApp NetCache C720

Deploying The NetCache
The NetCache 4.1 beta we evaluated caches HTTP 1.0 and 1.1, FTP (proxy mode), NNTP, Gopher, with support for SSL and persistent connections. This new release also supports three streaming multimedia formats—Apple QuickTime, Microsoft Windows Media, and RealNetworks G2—using RTSP and MMS (transparent mode) protocols. NNTP, RTSP, and MMS licenses are added-cost options.

Network Appliance provides the most rigorous Deployment Guide we've seen to date. It summarizes benefits, limitations, load distribution, failover, routing, and firewall considerations for forward and transparent proxy strategies. An entire chapter is dedicated to news caching. Web acceleration (reverse proxy) scenarios and example ISP, enterprise, and satellite networks are illustrated. NetApp deserves kudos on this strategic Guide; however, sizing metrics are notably absent.

We tested the NetCache as a simultaneous forward, transparent, and reverse web proxy, and as a streaming multimedia appliance. The squid proxy port (3128) is assigned by default. We also used policy-based routing for transparency to test features unavailable in forward proxy mode (MMS streaming and web server bypass). Redirection can also be accomplished with L4/L7 switches from partners Alteon, ArrowPoint, Foundry, or RADWARE, or with Cisco routers and WCCP 1.0.

When used as a web accelerator, the NetCache can accelerate a single server, or several servers with different content, but cannot distribute requests across servers with identical content (the reverse proxy configuration we tested for other products). The Deployment Guide recommends against DNS round robin request distribution, suggesting third-party server load balancers or WCCP to balance requests across multiple NetCaches.

The NetCache supports two alternatives for workload distribution: simple hierarchies and clusters. A simple hierarchy uses ICP queries between child, parent, and neighbor caches. We successfully configured our NetCache to query an ICP parent for all ISP-Planet.com requests (left). A cluster treats a group of NetCaches as a virtual parent.

In high-availability networks, deploy NetCaches in redundant "takeover pairs" connected to the same LAN segment. The pair exchange heartbeat queries over a dedicated Ethernet (typically a cross-over cable). If one cache goes down, the partner assumes the failed unit's address and handles HTTP, FTP, and Gopher (but not NNTP or ICP) requests. Responsibility reverts when the failed unit next answers a heartbeat. We configured a takeover pair with our eval unit and a phantom partner, then were surprised to see takeover status showing "partner up". Upon investigation, we found this means no takeover has occurred; based on our feedback, Network Appliance plans to modify this status text.

Network Appliance is active in the design of industry protocols like NECP (Network Element Control Protocol) and ICAP (Internet Content Adaptation Protocol) which enable cooperation between caches and third-party network servers. For example, ICAP will allow content to be "vectored" to an anti-virus server, where it can be scanned, then returned to the cache for storage. On subsequent requests, the clean content can be vended by the cache without repeating the scan. This is one of many possible uses for ICAP, now being tested within the ICAP Forum. ICAP will be provided as a NetCache software upgrade in a future release.

Introduction/The Platform	Caching Web Objects
DHCP-Assisted Setup	Tuning Your Web Cache
Managing the NetCache <	News Caching
Deploying The NetCache	Streaming Multimedia
> Authenticated, Controlled Access	Advanced Monitoring
Maintenance, NOW, and Support Programs/Final Words