Cisco 2851 Integrated Services Router (Flagship 2800 Series) Full Product Description

1. Short Overview

Naming & Variant Breakdown

• CISCO2851/K9: Standard AC-powered flagship router with IP Base IOS and K9 AES/3DES crypto licensing
• CISCO2851-AC-IP/K9: AC variant with integrated inline PoE power distribution for IP phones via switch HWICs
• CISCO2851-DC/K9: 48V negative DC telecom-grade power model for central office rack deployments
• -SEC/K9: Pre-bundled Advanced Security IOS image with zone-based firewall and IOS IPS enabled
• -HSEC/K9: High-security bundle factory-equipped with AIM-VPN/EPII PLUS high-performance encryption module
• -VOICE/K9: Unified Communications bundle preconfigured with PVDM DSP modules and full CME/SRST voice licensing

Core Differentiators vs Cisco 2821

1. NME-XD double-wide extended network module slot(standard NME-X on 2821) supporting larger high-density T1/E1 trunk, storage, and security modules
2. Maximum throughput increased to 75 Mbps mixed voice/data/security vs 60 Mbps on the 2821
3. Optimized system bus for aggregated multi-T1/E1/xDSL WAN uplinks and hundreds of concurrent VoIP calls
4. Identical core expansion layout: 4 HWIC universal slots, 1 EVM voice slot, 3 PVDM DSP slots, 2 AIM acceleration slots, dual Gigabit Ethernet, dual USB ports, RPS redundant power support
5. Same default 256MB DRAM / 64MB Flash, max 1GB DRAM / 256MB Flash memory ceiling
6. Largest physical chassis weight and full-module power budget of all 2800 series routers

2. Hardware Interface & Physical Specifications

Modular Expansion Architecture

1. 1 × NME-XD Double-Wide Enhanced Network Module slot (Exclusive to 2851)
   High-density rear slot supporting enterprise-grade double-wide trunk, security, and storage modules unavailable on the 2821:
   • NM-4T1/NM-8E1 multi-port channelized T1/E1 PRI voice trunk modules for large PBX interconnection
   • NM-CIDS-K9 dedicated inline intrusion detection modules
   • AIM-CUE storage modules for Unity Express voice mail and auto-attendant
2. 1 × EVM Extension Voice Module slot
   Dedicated voice expansion slot for additional analog/digital voice cards, remote terminal server modules, and auxiliary DSP offloading to free up HWIC/NME slots for WAN connectivity.
3. 4 × Rear Universal HWIC/WIC/VIC/VWIC slots
   Accept single-wide HWIC, double-wide HWIC-D, legacy WIC, analog VIC, and multi-flex VWIC voice cards; two slots support double-wide high-bandwidth HWIC-D modules:
   • HWIC: ADSL2+, VDSL2, G.SHDSL, synchronous serial, 4-port Fast Ethernet switch HWICs
   • WIC: ISDN BRI, asynchronous serial, analog modem WICs for dial-on-demand backup links
   • VIC/VWIC: FXS/FXO/E&M analog station/trunk cards, multi-port fractional T1/E1 voice trunks
4. 3 × Internal motherboard PVDM DSP slots
   Host Packet Voice Digital Signal Processor modules to handle VoIP codecs, G.168 echo cancellation, T.38 fax relay, and multi-party audio conferencing without occupying external expansion slots; sufficient DSP capacity for hundreds of concurrent voice callsCisco.
5. 2 × Internal AIM (Advanced Integration Module) daughtercard slots
   Dual independent slots for parallel multi-workload offloading: AIM-VPN/EPII PLUS high-speed encryption, AIM-ATM SAR processing, AIM-COMPRESS data compression to reduce CPU overhead for heavy VPN and WAN traffic.

Fixed Built-in Rear Panel Ports

1. 2 × Auto-MDI-X 10/100/1000BASE-T Gigabit Ethernet (GE0/0, GE0/1)
   Auto-negotiates 10/100/1000 Mbps full/half duplex; fully supports IEEE 802.1Q VLAN trunking, inter-VLAN routing, LACP link aggregation to isolate corporate, finance, guest, and sensitive POS payment subnets.
2. RJ45 Serial Console port (115.2 kbps max baud) – local out-of-band CLI management
3. RJ45 AUX port – remote emergency access via external PSTN analog modem
4. 2 × USB 1.1 Type-A ports– secure crypto authentication tokens, offline configuration/log backup storage
5. Removable external CompactFlash (CF) slot – primary persistent storage for IOS images, full running configurations, and centralized event logging
6. Power inlet: Standard IEC AC socket (DC variant uses 48V negative terminal block telecom input)
7. RPS redundant power supply connector for high-availability branch deployments
8. Chassis ground lug + Kensington anti-theft lock slot for physical rack chassis security

Memory & Performance Benchmarks

• Processor: High-performance multi-task RISC core with dedicated onboard crypto FPGA hardware acceleration
• Default DRAM: 256MB SDRAM; maximum expandable DRAM: 1024MB (1GB) via dual 512MB DIMM slots
• Default Flash memory: 64MB CompactFlash; maximum supported Flash: 256MB CF card
• Multi-service mixed voice/data/security throughput: Up to 75 Mbps aggregate wire-speed performance (highest in 2800 series)
• Hardware crypto acceleration: Native AES-256, 3DES, DES IPsec and SSL/TLS VPN offloading; scalable via dual AIM-VPN/EPII PLUS modules
• Maximum concurrent site-to-site IPsec tunnels: Up to 300+, expandable with full 1GB DRAM and dual AIM encryption hardware
• Supported IOS releases: Cisco IOS 12.3T, 12.4 mainline / 12.4T universal multi-service images; feature sets unlocked via permanent chassis-bound software licenses (IP Base, Advanced Security, Unified Communications)
• Voice capacity: PVDM2/PVDM3 DSP modules support up to 192 concurrent VoIP calls; Cisco CME embedded call processing for up to 250 IP phones, SRST survivable remote branch telephony, Unity Express voice mail for up to 500 mailboxes

Physical & Power Parameters

• Form factor: 2U standard 19-inch rack-mount metal chassis with integrated rack ears
• Standard AC power supply: 100–240V 50/60Hz universal autoranging input
• DC variant (C2851-DC): 48V negative DC telecom input for central office cabinet deployments
• PoE variant (C2851-AC-IP): Integrated inline power distribution to feed IP phones via compatible switch HWIC modules
• Typical chassis power consumption: ~90W under fully loaded NME-XD/EVM/HWIC/PVDM/AIM module configuration
• Front panel status LEDs: System power, fault alarm, CompactFlash activity, dual USB port status, PVDM/AIM health indicators, four HWIC slot link/activity, dual Gigabit Ethernet link/activity
• Operating environment
  • Operating temperature: 0°C to +40°C below 1800m altitude; 0°C to +25°C above 1800m up to 3000m
  • Relative humidity: 10–85% RH non-condensing
• Dimensions (H × W × D): 8.9 × 44.5 × 43.8 cm (3.5 × 17.25 × 16.4 inches)
• Fully loaded weight: ~11.4 kg (25.1 lbs), heaviest chassis of all 2800 series routers
• No native chassis PoE output except for dedicated -AC-IP power supply variant.

3. Cisco IOS Universal Image Multiservice Feature Suite

Core Routing & Multi-WAN Connectivity

• Full IPv4 routing stack: Static routes, RIP v1/v2, OSPF, EIGRP, BGP (Advanced IP Services license)
• WAN encapsulation support: PPP, HDLC, Frame Relay, ATM, ISDN, PPPoE/PPPoA for DSL, Dial-on-Demand Routing (DDR) for automatic backup failover
• HSRP/VRRP for router high availability redundancy; NHRP DMVPN hub-spoke multi-site overlay VPN architecture
• NAT services: Static NAT, dynamic NAT, PAT overloading, multi-address NAT pools, NAT64 IPv4-IPv6 transition support
• IEEE 802.1Q VLAN trunking, inter-VLAN routing, storm control, LACP link aggregation across dual Gigabit Ethernet onboard ports.

Unified Communications Voice & Fax Integration (Flagship High-Density Voice Differentiator)

1. VoIP signaling protocols: H.323, SIP, MGCP, SCCP native support for large-scale Cisco Unified IP Phone deployments
2. Analog/digital telephony via VIC/VWIC + PVDM DSPs + EVM voice cards: FXS station ports, FXO PSTN trunk lines, E&M PBX tie connections, multi-port T1/E1 PRI voice trunks via NME-XD modules
3. T.38 real-time fax relay over IP, fax passthrough, store-and-forward fax routing
4. DSP-accelerated voice codecs: G.711, G.729a, G.726, wideband G.722 high-fidelity audio
5. Enterprise telephony tools: Scalable multi-site dial plans, voice hunt groups, toll bypass to eliminate expensive long-distance PSTN charges
6. CME embedded call manager, SRST survivable remote telephony, Unity Express voice mail/auto-attendant hosted via AIM-CUE storage modules.

Enterprise QoS & WAN Optimization

• Base QoS tools: Weighted Fair Queuing (WFQ), per-interface traffic shaping
• Advanced QoS (Security/UC license): Low Latency Queuing (LLQ), Frame Relay Traffic Shaping (FRTS), WRED congestion avoidance, DSCP/802.1p traffic marking
• Link Fragmentation and Interleaving (LFI), cRTP VoIP header compression to eliminate voice jitter over low-speed DSL/ISDN backup links
• NBAR2 next-generation deep packet inspection for application-aware traffic prioritization of business-critical software.

Integrated Self-Defending Network Security Suite

1. Zone-Based Stateful Firewall (ZBFW): Deep application-layer inspection for HTTP, FTP, SIP, H.323 and all mainstream enterprise business protocols
2. IOS IPS inline signature-based intrusion prevention with real-time threat detection and automated connection blocking
3. Dual AIM hardware-accelerated VPN stack:
   • AES-256/3DES/DES IPsec site-to-site branch tunnels
   • Cisco Easy VPN Remote centralized security policy provisioning for remote branch locations
   • DMVPN scalable hub-spoke multi-site overlay networks
   • SSL VPN for browser-only remote worker access without client software
4. AAA security framework: PAP/CHAP authentication, RADIUS/TACACS+ centralized access control and complete audit logging
5. Standard/extended ACLs, dynamic ACLs, anti-DDoS traffic policing, security zone segmentation to isolate sensitive POS payment and finance subnets.

Management, Automation & Operations

• Dual out-of-band management interfaces: Serial Console and AUX modem port for emergency offline IT maintenance
• Secure remote management: SSHv2, HTTPS, SNMP v3 (backward compatible with SNMP v1/v2c)
• Graphical configuration utility: Cisco Configuration Professional (CCP) for simplified zero-touch mass branch deployment
• AutoInstall automated remote IOS image and configuration download over WAN links for nationwide branch rollouts
• Removable CompactFlash storage for easy IOS upgrades, configuration backup, and centralized log archiving
• Persistent syslog event logging, NTP time synchronization for consistent audit log timestamps
• Dual USB ports for offline config storage and two-factor authentication security tokens.

4. Typical Deployment Scenarios

1. Large regional enterprise headquarters multi-service edge gateway: Multiple aggregated T1/E1 PRI trunks via NME-XD double-wide network module, dual fiber Metro Ethernet primary/secondary WAN uplinks, VDSL2 HWIC copper backup link, EVM analog voice expansion card for dozens of analog fax/desk phones, three PVDM DSP modules supporting over 180 concurrent VoIP calls, dual Gigabit Ethernet ports to segregate finance, engineering, staff, and guest VLANs, high-volume DMVPN IPsec tunnels to corporate headquarters, integrated ZBFW/IPS security stack for enterprise compliance.
2. National multi-chain retail flagship voice gateway: ADSL2+ HWIC primary broadband WAN, ISDN BRI WIC dial backup, CME embedded call processing for 200–250 on-site IP phones, NME-CIDS intrusion detection module for PCI DSS payment security, dual AIM slots for parallel VPN encryption and data compression for hundreds of store site-to-site VPN connectivity.
3. Global carrier managed high-capacity enterprise CPE: Universal dual-standard DSL HWIC copper broadband access, NME-XD storage module for local log retention, dual AIM acceleration modules for mass customer VPN offloading, DMVPN overlay to carrier central service hub, integrated firewall/IPS for tenant threat isolation and network segmentation.
4. Advanced enterprise networking training lab core router: Universal NME-XD/EVM/HWIC/WIC/VIC modularity to teach high-density multi-T1/E1 PRI voice trunking, dual Gigabit multi-VLAN inter-routing, hardware-accelerated high-volume IPsec VPN, and full unified communications gateway labs; full 1GB DRAM and large CF capacity fully support feature-rich IOS 12.4T images unavailable on all lower-tier 2801/2811/2821 routers.

5. Standard Package Contents of CISCO2851 / 2851-DC / 2851-AC-IP

Separately Sold Optional Accessories

• HWIC/WIC/VIC/VWIC WAN and analog/digital voice interface cards
• NME / NME-XD enhanced double-wide network modules (multi-T1/E1 trunk, IDS, Unity Express storage)
• EVM Extension Voice Modules for additional voice/terminal server ports
• PVDM2/PVDM3 DSP voice compression modules for VoIP and T.38 fax relay
• AIM daughtercards: AIM-VPN/EPII PLUS encryption, AIM-ATM SAR processing, AIM-COMPRESS data compression, AIM-CUE voice mail storage
• DRAM memory expansion DIMMs (256MB / 512MB / 1024MB)
• CompactFlash memory upgrades (64MB / 128MB / 256MB)
• CAT5e/CAT6 Gigabit Ethernet patch cords, RJ11 DSL/ISDN telephone line cables
• External PoE injectors for non-PoE IP cameras and wireless access points
• External redundant power supply units (RPS) for high-availability branch deployments

Software Licensing Information

Short Commercial Catalog Summary