Introducing the Cache Engine

This chapter describes the Cisco Cache Engine, its specifications, and considerations for using the system. Before you install the Cache Engine, take time to carefully plan the placement of the Cache Engine on your networks. This helps ensure that you receive the maximum benefit of caching web traffic.

Overview

The Cache Engine is a special-purpose hardware and software carrier-class solution that has been designed from the ground up as a loosely coupled, multinode network system optimized to provide robust shared network caching.

The Cache Engine works with routers running Cisco IOS software with the Web Cache Communication Protocol (WCCP). WCCP redirects Hypertext Transfer Protocol (HTTP) traffic to a Cache Engine; the Cache Engine then manages the web request. See Appendix B, "Web Cache Communication Protocol Version 1," for more information on WCCP, Version 1. See Appendix C, "Web Cache Communication Protocol Version 2," for more information on WCCP, Version 2.

The Cache Engine works in tandem with a router to handle web traffic. This traffic includes user requests to view pages and graphics (objects) on World Wide Web servers, whether internal or external to your network, and the replies to
those requests.

When a user requests an object from a web server, the router first sends the request to a Cache Engine. If the Cache Engine has a copy of the requested object in storage, the Cache Engine sends the user the object. Otherwise, the Cache Engine gets the requested objects from the web server, stores a copy of the objects (caches them), and simultaneously forwards the objects on to the user.

By caching web objects in this manner, the Cache Engine can speed the satisfaction of user requests if more than one user wants to access the same objects. This also reduces the amount of traffic between your network and the Internet, potentially improving your overall network performance and optimizing your bandwidth usage.

Cache Engine Specifications

Table 1-1 lists the specifications of the Cache Engine.

Table 1-1: Cisco Cache Engine Specifications

¹One additional 9.1-GB Ultra2 LVD SCSI disk drive can be added to the Model 505 to increase storage.

Specifications	Model 505	Model 550	Model 570
Hard disk storage	1 9.1-GB Ultra2 LVD SCSI hard drive¹	2 9.1-GB Ultra2 LVD SCSI hard drives	2 18-GB Ultra2 LVD SCSI hard drives
Memory	8-MB Flash memory 128-MB SDRAM 256-KB EPROM 512-KB L2 cache	8-MB Flash memory 256-MB SDRAM 256-KB EPROM 512-KB L2 cache	8-MB Flash memory 384-MB SDRAM 256-KB EPROM 512-KB L2 cache
CPU	266 MHz	366 MHz	375 MHz
Ethernet controller	Intel 82588	Intel 82588	Intel 82588
Dimensions	Height: 1.72 inches (43.69 mm) Width: 17.5 inches (444.50 mm) Depth: 14.1 inches (358.14 mm)	Height: 1.72 inches (43.69 mm) Width: 17.5 inches (444.50 mm) Depth: 14.1 inches (358.14 mm)	Height: 1.72 inches (43.69 mm) Width: 17.5 inches (444.50 mm) Depth: 14.1 inches (358.14 mm)
Weight	11.2 pounds (5.08 kg)	12.5 pounds (5.67 kg)	12.5 pounds (5.67 kg)
Power	Universal input: 100-120 VAC 200-240 VAC Freqency: 50-60 Hz Maximum power: 65 watts	Universal input: 100-120 VAC 200-240 VAC Freqency: 50-60 Hz Maximum power: 65 watts	Universal input: 100-120 VAC 200-240 VAC Freqency: 50-60 Hz Maximum power: 65 watts
Current	120-VAC input, with PFC (power factor correction) 1.05A 230-VAC input, with PFC (power factor correction) 0.51A	120-VAC input, with PFC (power factor correction) 1.05A 230-VAC input, with PFC (power factor correction) 0.51A	120-VAC input, with PFC (power factor correction) 1.05A 230-VAC input, with PFC (power factor correction) 0.51A
Connectors	Console: 1 RJ-45 connector Network: 2 10/100 BaseTX Ethernet RJ-45 connectors (MDI) External SCSI: 68-pin high-density connector (Ultra2 LVD) Support for a maximum of 80 MBps data transfer	Console: 1 RJ-45 connector Network: 2 10/100 BaseTX Ethernet RJ-45 connectors (MDI) External SCSI: 68-pin high-density connector (Ultra2 LVD) Support for a maximum of 80 MBps data transfer	Console: 1 RJ-45 connector Network: 2 10/100 BaseTX Ethernet RJ-45 connectors (MDI) External SCSI: 68-pin high-density connector (Ultra2 LVD) Support for a maximum of 80 MBps data transfer
Maximum station-to-station cabling distances	10/100BaseTX Ethernet: Category 5 UTP: 328 ft (100 m) SCSI Ultra2 LVD: 12 m maximum	10/100BaseTX Ethernet: Category 5 UTP: 328 ft (100 m) SCSI Ultra2 LVD: 12 m maximum	10/100BaseTX Ethernet: Category 5 UTP: 328 ft (100 m) SCSI Ultra2 LVD: 12 m maximum
LEDs	Power System LINK (2) 100 Mbps (2) Drive 0 Drive 1 SW Status (4)	Power System LINK (2) 100 Mbps (2) Drive 0 Drive 1 SW Status (4)	Power System LINK (2) 100 Mbps (2) Drive 0 Drive 1 SW Status (4)
Agency approvals	FCC Class A (47 CFR Part 15) EN 55022A Class B on shielded UTP VCCI Class A UL 1950 CSA-C22.2 No. 950 IEC 60950 EN 60950 CE Mark	FCC Class A (47 CFR Part 15) EN 55022A Class B on shielded UTP VCCI Class A UL 1950 CSA-C22.2 No. 950 IEC 60950 EN 60950 CE Mark	FCC Class A (47 CFR Part 15) EN 55022A Class B on shielded UTP VCCI Class A UL 1950 CSA-C22.2 No. 950 IEC 60950 EN 60950 CE Mark
Placement	Rack-mounted, mid, front, or back (standard 19-inch and 23-inch racks)	Rack-mounted, mid, front, or back (standard 19-inch and 23-inch racks)	Rack-mounted, mid, front, or back (standard 19-inch and 23-inch racks)
Temperature	Operating: 41 to 104°F (5 to 40°C) Nonoperating: -13 to 158°F (-25 to 70°C)	Operating: 41 to 104°F (5 to 40°C) Nonoperating: -13 to 158°F (-25 to 70°C)	Operating: 41 to 104°F (5 to 40°C) Nonoperating: -13 to 158°F (-25 to 70°C)
Operating humidity	5 to 95%, noncondensing	5 to 95%, noncondensing	5 to 95%, noncondensing

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