Cisco 1600 series routers connect small offices with Ethernet LANs to WANs through Integrated Services Digital Network (ISDN), asynchronous serial, and synchronous serial connections.

The five basic configurations of the Cisco 1600 product family offer the following ports:

• Cisco 1601 R — one Ethernet, one serial, one WAN interface

• Cisco 1602 R — one Ethernet, one serial with integrated 56-kbps DSU/CSU, one WAN interface card slot

• Cisco 1603 R — one Ethernet, one ISDN Basic Rate Interface (BRI) (S/T interface), one WAN interface card slot

• Cisco 1604 R — one Ethernet, one ISDN BRI with integrated NT1 (U interface), one S-bus port for ISDN phones, one WAN interface card slot

• Cisco 1605 R — two Ethernet slots, one WAN interface card slot

The serial WAN port on the Cisco 1601 R router supports asynchronous serial connections of up to 115.2 kbps and synchronous serial connections — such as Frame Relay, leased lines, Switched 56, Switched Multimegabit Data Service (SMDS), and X.25 — of up to 2.048 Mbps. The Cisco 1602 R router integrates a 56-kbps four-wire DSU/CSU, and it supports the same synchronous serial connections as the Cisco 1601 R router (except SMDS). The ISDN BRI port on the Cisco 1603 R router has an S/T interface, while the Cisco 1604 R includes an integrated NT1 with a U interface. The Cisco 1605 R router provides a 10BaseT and an AUI port on the first Ethernet interface and a 10BaseT port on the second Ethernet interface.

The 1601 R-1605 R routers have a "run-from-RAM" architecture; the "R" suffix designates run from "RAM". The Cisco IOS software image is stored in Flash memory (in compressed form), but is loaded into RAM before being executed by the router.

Cisco 1601 R Rear View

Cisco 1602 R Rear View

Cisco 1603 R Rear View

Cisco 1604 R Rear View

Cisco 1605 R Rear View

The ISDN BRI Leased Line S/T card is designed specifically for the Cisco 1603 R and 1604 R routers. It is intended for users who require a dial-up ISDN BRI line (from the Cisco 1603 R or 1604 R router`s fixed-WAN port) and an ISDN leased line (from the ISDN BRI Leased Line card inserted into the Cisco 1603 R or 1604 R router). This card is automatically configured only in ISDN leased line mode.

1. Line must be provisioned as T1 or fractional T1, that is N x 64 or N x 56 (N=1 through 24) unchannelized and clocked at 1.544 Mbps. A dedicated 64Kbps leased line would not be supported if clocked at 64Kbps, for example, but would be supported if provisioned as fractional T1 (in other words, clocked at 1.544 Mbps).

• Asynchronous serial protocols: Point-to-Point Protocol (PPP), Serial Line Internet Protocol (SLIP)

• Asynchronous interface: EIA/TIA-232

• Synchronous serial WAN services: Frame Relay, X.25, SMDS

• Synchronous serial protocols: PPP, HDLC, LAPB, IBM/SNA

• Synchronous serial interfaces supported on Cisco 1601 R and WIC-1T card: EIA/TIA-232, V.35, X.21, EIA/TIA-449, EIA-530