Cisco 1921 ISR G2 Full Product Description

1. Short Overview

TheCisco 1921 (ISR G2)is a 1U rack-mount modular second-generation Integrated Services Router from the Cisco 1900 Series ISR G2 family, targeted at small-to-medium enterprise branch offices, retail locations, service provider managed CPE, and enterprise remote sites. It succeeds the Cisco 1841, delivering dual Gigabit Ethernet onboard ports, improved multi-core processing, built-in hardware VPN acceleration, flexible EHWIC modular expansion with backward compatibility for HWIC/WIC/VWIC modules from ISR 1800 Series, unified IOS universal image licensing, and energy-efficient intelligent power management. This platform reached End-of-Sale (EoS) and End-of-Life (EoL) status and no longer receives official Cisco support; modern replacements are the ISR 4000 and Catalyst 8000 Series edge routersCisco.

Naming & Standard Variants

Cisco 1921/K9: Base universal security model with permanent IPsec/SSL crypto hardware acceleration
Cisco 1921-SEC/K9: Pre-activated security license bundle
Cisco 1921DC/K9: DC power input variant for industrial, telecom rack deployments

Core Differentiators vs Cisco 1841

Dual native 10/100/1000 Gigabit Ethernet ports (1841 only offers Fast Ethernet)
New EHWIC high-speed modular slot architecture, backward compatible with all 1800-series HWIC/WIC/VWIC cards
Unified Cisco IOS Universal image with subscription license activation (no separate feature images)
Higher WAN throughput: Up to 15 Mbps concurrent multi-service performance vs ~10 Mbps on 1841
Dual USB 2.0 host ports, dual console access (RJ45 + mini USB console)
Intelligent energy-saving power management, high-efficiency internal power supply
Larger standard memory footprint (default 512MB DRAM / 256MB Flash)
Integrated hardware crypto engine native to motherboard, no mandatory AIM VPN module

2. Hardware Interface & Performance Specifications

Modular Expansion Slots

2 × EHWIC slots: Support either two single-wide EHWIC/HWIC/WIC/VWIC cards or one double-wide EHWIC-D module
Supported module types:
- Serial synchronous/asynchronous, T1/E1/FT1 integrated DSU/CSU
- ADSL2+, VDSL2, G.SHDSL broadband DSL WAN cards
- ISDN BRI, analog modem WICs for dial backup
- 4-port Fast Ethernet switch HWICs for extended LAN segmentation
- Voice VWIC cards for analog/digital trunk telephony (DSP PVDM modules sold separately)
No internal AIM slots; crypto acceleration is fully onboard hardware

Fixed Built-in Physical Ports (Rear Panel)

2 × Auto-MDI-X 10/100/1000BASE-T Gigabit Ethernet (GE0/0, GE0/1)

Full auto-negotiation, 802.1Q VLAN trunking, inter-VLAN routing, LACP link aggregation support
Dual Console Access:
- RJ45 serial console port (115.2 kbps max baud)
- Mini Type-B USB 2.0 console port for PC direct out-of-band management
RJ45 AUX port: Remote out-of-band management via external analog PSTN modem
2 × USB 2.0 Type-A host ports: For USB LTE cellular dongle wireless backup, USB flash storage for config/ log archiving, authentication tokens
Power inlet: Standard AC IEC socket (DC variant uses terminal block DC input)
Kensington anti-theft lock slot for rack physical security

Memory & Performance Benchmarks

Default DRAM: 512MB; maximum expandable DRAM: 2GB
Default Flash memory: 256MB; maximum supported Flash: 2GB CompactFlash
Maximum concurrent multi-service throughput: 15 Mbps mixed voice/data/security workloads
Onboard dedicated hardware crypto accelerator: Native AES-256, 3DES, DES IPsec + SSL VPN offload
Max concurrent site-to-site IPsec tunnels: 200+; scalable with DRAM upgrade
Supported IOS releases: Cisco IOS 15.x Universal images (IP Base, Security, Unified Communications, Data licenses activated via software license keys)
Voice capacity: Supports PVDM2/PVDM3 DSP modules on VWIC slots for VoIP, T.38 fax relay, voice conferencing

Physical & Power Parameters

Form factor: 1U standard 19-inch rack-mount metal chassis, integrated rack ears
Internal high-efficiency universal AC power supply (100–240V 50/60Hz); DC variant supports 48V DC input
Max platform power consumption: 110W
Front panel LEDs: System power, module slot status, dual GE link/activity, USB activity, crypto engine status, fault alarm
Operating environment: Indoor wiring closet / office deployment
- Operating temp: 0°C to +40°C below 1800m altitude; 0°C to +25°C above 1800m up to 3000m
- Humidity: 10–85% RH non-condensing
Acoustic noise: Typical 33 dBA, max 58 dBA under full load
No native chassis PoE output; PoE EHWIC modules provide 802.3af/ePoE inline power to connected endpoints

3. Cisco IOS Universal Image Feature Suite

Core Routing & Multi-WAN Connectivity

IPv4 full routing stack: Static, RIP v1/v2, OSPF, EIGRP, BGP
WAN encapsulations: PPP, HDLC, Frame Relay, PPPoE, PPPoA, ISDN, DDR dial backup
HSRP, VRRP for router redundancy; NHRP DMVPN hub-spoke multi-site overlay VPN
NAT services: Static NAT, dynamic NAT, PAT overloading, NAT64
IEEE 802.1Q VLAN trunking, inter-VLAN routing, LACP Ethernet link aggregation

Unified Communications & VoIP Features

Voice call control: H.323, SIP, MGCP, SCCP for Cisco IP phone integration
Analog/digital telephony via VWIC + PVDM DSP modules: FXS/FXO/E&M trunk support
T.38 real-time fax relay, voice compression (G.711, G.729a, G.726), echo cancellation
Toll bypass, multi-site dial plans, voice hunt groups, video over IP support

Enterprise QoS & WAN Optimization

Full layered QoS toolkit: LLQ, CBWFQ, WFQ, WRED, DSCP/802.1p marking
Link Fragmentation and Interleaving (LFI), cRTP VoIP header compression
WAN traffic shaping for Frame Relay, DSL, Metro Ethernet, bandwidth policing
Application-aware QoS via NBAR2 deep packet inspection for business traffic prioritization

Integrated Self-Defending Network Security

Stateful Zone-Based Firewall (ZBFW): Application-layer deep inspection for HTTP, FTP, SIP, H.323
Embedded IOS IPS signature-based inline intrusion prevention and threat mitigation
Hardware-accelerated VPN suite:
- AES-256/3DES IPsec site-to-site tunnels
- Cisco Easy VPN Remote centralized policy deployment
- DMVPN scalable multi-site overlay networks
- SSL VPN for browser-based remote worker access without client software
AAA security framework: RADIUS/TACACS+, PAP/CHAP, 802.1X wired port authentication, NAC endpoint compliance
URL filtering, dynamic ACLs, anti-DDoS policing, traffic segmentation via security zones

Management, Automation & Operations

Dual console management: RJ45 serial + mini USB console
Secure remote access: SSHv2, HTTPS, SNMP v3 (SNMP v1/v2c backward support)
Web-based Cisco Configuration Professional (CCP) GUI for simplified provisioning
Syslog logging, NTP time synchronization, RMON traffic statistics collection
AutoInstall zero-touch remote deployment over WAN links
Dual Flash bank storage for primary/backup IOS image disaster recovery
USB mass storage support for offline configuration archives and persistent logging
Intelligent power monitoring, energy-saving idle module power reduction

4. Typical Deployment Scenarios

Medium regional enterprise branch edge router: Dual Gigabit Ethernet primary/secondary Metro Ethernet uplinks, T1 EHWIC leased-line backup, PVDM DSP modules for multi-line office VoIP, ZBFW firewall + IPsec DMVPN tunnel to corporate headquarters, VLAN segmentation for finance, HR, engineering and guest subnets
Global DSL carrier managed business CPE: VDSL2 EHWIC copper broadband access, dual GE ports for multi-segment enterprise LAN, integrated security suite for customer threat protection, DMVPN overlay to carrier central service hub
Multi-store retail flagship rack router: PoE-capable EHWIC switch module powering POS security cameras and IP phones, dual GE redundant fiber uplinks, USB LTE dongle fourth-layer wireless failover, SSL VPN for store manager remote access
Industrial remote M2M site aggregation router: Serial EHWIC for SCADA leased-line connectivity, DC power variant for telecom cabinet deployment, AUX modem out-of-band management, encrypted IPsec tunnels for secure industrial data transmission

5. Standard Package Contents of Cisco 1921/K9

1 × Cisco 1921 1U rack-mount router chassis (no EHWIC/HWIC/VWIC/PVDM modules included)

IEC AC power cord (DC variants exclude AC cord)

RJ45 console rollover cable

Mini USB console cable

Hardware installation quick start guide

Global safety, EMC, RoHS regulatory compliance documentation

Separately Sold Optional Accessories

EHWIC/HWIC/WIC/VWIC WAN and switch interface cards
PVDM2/PVDM3 DSP modules for VoIP/fax relay
PoE-enabled EHWIC modules for inline 802.3af/ePoE power
CompactFlash memory upgrades (512MB / 1GB / 2GB)
CAT5e/CAT6 Gigabit Ethernet patch cords, RJ11 DSL/ISDN telephone cables
CAT4/CAT6 USB LTE cellular dongles for auxiliary wireless backup WAN
USB flash storage drives for offline configuration and log archiving
External high-gain cellular antennas for USB dongles
External PoE injectors for non-PoE endpoint devices

Software Licensing Information

The Cisco 1921 runs a single universal IOS image covering all feature sets; functions are unlocked via permanent software license keys: IP Base, Security, Unified Communications, Data. Crypto-enabled K9 images include built-in hardware IPsec/SSL VPN acceleration and comply with US ITAR export regulations. No separate hardware crypto modules are required. Licenses are perpetual and bound to the router chassis serial number.

Short Commercial Catalog Summary

The Cisco 1921 is a legacy 1U rack-mount modular ISR G2 second-generation integrated services router from the Cisco 1900 Series, designed for small-to-medium enterprise branch offices, retail flagship locations, and carrier-managed business CPE deployments. As the upgraded successor to the Cisco 1841, it features two native 10/100/1000 Gigabit Ethernet onboard ports, two flexible EHWIC modular slots with full backward compatibility for ISR 1800-series WIC/HWIC/VWIC modules, dual USB 2.0 host ports, dual RJ45 + mini USB console access, integrated motherboard hardware AES/3DES VPN acceleration, high-efficiency internal power supply, and intelligent energy-saving power management. Running a single Cisco IOS universal image with software license activation for routing, security, unified communications, and data features, it consolidates rack router, multi-VLAN switch, stateful zone-based firewall, IPS intrusion prevention, multi-path hardware-accelerated VPN gateway, enterprise QoS, and optional VoIP voice gateway functionality into one compact 1U rack unit, eliminating multiple standalone network appliances. Key advantages over the 1841 include Gigabit Ethernet, higher multi-service throughput, unified IOS licensing, expanded memory capacity, and dual-form-factor console access. As an end-of-life unsupported legacy platform, it is only suitable for lab environments, existing legacy network refresh replacements, and non-critical production sites, with the Cisco ISR 4000 and Catalyst 8000 Series recommended as its modern performance, security, and modular upgrade replacements. Limitations include discontinued Cisco software maintenance, no WiFi native chassis option, and aging processing architecture compared to current edge routing platforms. The router complies with UL, IEC, EN, EMC, and RoHS global indoor commercial wiring closet safety and electromagnetic standards.


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