Cisco ISR4321/K9 Integrated Services Router (4000 ISR Series) Full Product Description

1. Short Overview

Naming & Variant Breakdown

• ISR4321/K9: Base AC-powered router, universal IOS XE consolidated image, embedded K9 AES/3DES crypto hardware, base 50 Mbps multi-service throughput
• ISR4321T-P/K9: PoE variant with integrated high-wattage inline power budget for 802.3af IP phones via EtherSwitch NIMs
• ISR4321-DC/K9: 24–60V negative DC autoranging telecom power model for central office rack deployments
• -SEC/K9: Pre-bundled Security license (Zone-Based Firewall, IOS IPS, full IPsec/DMVPN/SSL VPN suite pre-activated)
• -VOICE/K9: Unified Communications bundle pre-licensed for CME/SRST, PVDM voice codec support
• -VSEC/K9: All-in-one Voice + Security converged branch bundle
• -AX/K9: Advanced Services bundle supporting SRE virtualization, WAAS wide-area deduplication, DNA Center advanced analytics
• -AXV/K9: AX + full UC voice bundle with voice feature set unlocked
• -RF / -WS: Refurbished / warranty service SKUs

Core Differentiators vs ISR4221/4221X

1. Native PVDM3 DSP slots for Cisco Unified Communications (CME/SRST voice, unsupported on all 4221 models)
2. Higher base throughput: 50 Mbps base, upgradeable to 100 Mbps (35→75 Mbps max on 4221)
3. Expandable DRAM via dual DIMM slots (fixed soldered single memory bank on 4221X)
4. Larger chassis power budget supporting simultaneous PoE NIM + PVDM voice modules
5. Dual PPE packet processing cores (single combined core on 4221) for separated forwarding and crypto workloadsCisco
6. Identical 1RU form factor, 2 NIM slots, 1 ISC internal service slot, dual GE RJ45 + shared SFP fiber port, triple console management, dual USB 2.0
7. Same IOS XE unified licensing architecture, SD-WAN Viptela native support, single CompactFlash storage

2. Hardware Interface & Physical Specifications

Modular Expansion Architecture

1. 2 × NIM (Network Interface Module) universal rear slots
   Each slot accepts single-wide NIM modules; double-wide NIM-D is not supported on ISR4321:

• Broadband: NIM-ADSL2+, NIM-VDSL2, NIM-G.SHDSL
• Serial/T1/E1: NIM-2T1, NIM-4E1, NIM-2B-S/T serial interface cards
• Wireless backup: NIM-4G-LTE global/NA/ST cellular WAN modules
• Switching: NIM-4GE EtherSwitch for on-site LAN and IP phone access
• Auxiliary security/access auxiliary interface cards

1. 1 × ISC (Integrated Services Card) internal slot
   Accommodates MSATA SSD storage for SRE virtualization logs, WAAS deduplication data, or lightweight auxiliary application offloading
2. 2 × Onboard PVDM3 DSP slots (Unique voice capability vs 4221 series)
   Dedicated Packet Voice Digital Signal Processor slots to handle VoIP codecs, G.168 echo cancellation, wideband G.722 audio, T.38 fax relay, multi-party conferencing; supports up to 192 concurrent VoIP calls for medium IP phone deployments

Built-in Rear Physical Ports

1. 2 × 10/100/1000BASE-T Gigabit RJ45 (GE0/0, GE0/1) + 1 shared SFP mini-GBIC fiber slot
   SFP port shares hardware with GE0/0; activating SFP disables the GE0/0 copper RJ45 port. All Gigabit ports support IEEE 802.1Q VLAN trunking, LACP link aggregation to segment corporate, finance, guest, and PCI payment subnets.
2. Primary RJ45 Serial Console port (115200 baud standard out-of-band CLI management)
3. Mini-USB Type-B secondary Console port for lightweight cable-free local configuration
4. RJ45 AUX port for remote dial-in emergency access via analog PSTN modem
5. 2 × USB 2.0 Type-A ports: High-speed offline config backup, logging storage, two-factor crypto authentication tokens
6. Removable CompactFlash storage slot (factory default 8GB, max supported 8GB capacity)
7. External DC power jack via external AC power brick (internal hot-swappable PSU only on PoE-T-Pvariant)
8. Dedicated external RPS redundant power supply connector for mission-critical high-availability branches
9. Chassis ground terminal + Kensington security lock slot for physical rack anti-theft protection

Memory & Performance Benchmarks

• Processor: Multi-core x86 architecture with two independent packet processing engines (separate forwarding and crypto planes) + dedicated embedded AES-256/3DES hardware offloadCisco
• DRAM: Dual DIMM slots, factory default 4GB ECC DDR3; maximum expandable to 8GB total via matched DIMM pairs
• Flash: Fixed max 8GB CompactFlash, single storage bank without redundancy
• Aggregate multi-service throughput: Base 50 Mbps; permanent performance license upgrade unlocks full 100 Mbps wire-speed multi-service throughput
• CEF pure routing throughput: Up to 1.5 Gbps for plain data-plane forwarding without security/voice overhead
• Maximum concurrent IPsec/DMVPN tunnels: Up to 400 tunnels at full 100 Mbps licensed throughput
• Supported IOS XE releases: IOS XE 16.x, 17.x universal consolidated images; all feature access controlled via permanent chassis-bound licenses
• Voice capacity: Dual PVDM3 DSP slots support up to 192 concurrent VoIP calls; Cisco CME embedded call processing for up to 150 IP phones, SRST survivable remote telephony, Unity Express voice mail

Physical & Power Parameters

• Rack form factor: 1RU standard 19-inch EIA rack mount, wall-mount bracket compatible
• Dimensions (H × W × D): 43.7 × 322.6 × 254 mm (1.72 × 12.7 × 10 inches)
• Empty chassis weight (no NIM/PVDM/ISC modules): 3.3 kg (7.3 lbs)
• Standard AC power supply: External autoranging AC brick (100–240V 50/60Hz input, 120W max output)
• PoE variant (ISR4321T-P): Internal hot-swappable PSU with 200W PoE budget, expandable to 750W via external PoE boost accessory
• Typical power consumption: 28W idle, max 75W with full NIM + dual PVDM module load
• Operating environmental specifications
  • Operating temperature: 0°C to +40°C at altitude below 1800m; performance derated above 1800m
  • Relative humidity: 5%–85% non-condensing
• MTBF: 562,180 hours under standard factory operating conditions

3. IOS XE Universal Feature Suite

Core Routing & Multi-WAN Connectivity

• Full dual-stack IPv4 / IPv6 routing suite: Static routes, RIP v1/v2, OSPF, EIGRP, BGP, IS-IS, PIM multicast suite, BFD bidirectional fast failure detection
• WAN encapsulations: PPP, HDLC, Frame Relay, ATM, ISDN, PPPoE/PPPoA for DSL, DDR backup failover, MPLS L2/L3 VPN, GETVPN
• Native Cisco SD-WAN Viptela support: Zero-touch provisioning, centralized policy orchestration, hybrid broadband/cellular/MPLS multi-link WAN architecture
• NAT services: Static NAT, dynamic PAT, multi-address NAT pools, NAT64 IPv6-to-IPv4 translation for cloud SaaS connectivity
• Layer 2 switching features: IEEE 802.1Q VLAN trunking, LACP link aggregation, storm control, port security, MAC address filtering

Unified Communications Voice & Fax (Activated via SL-4300-UC-K9 License)

1. VoIP signaling protocols: H.323, SIP, MGCP, SCCP native support for medium-scale Cisco Unified IP Phone deployments
2. Analog/digital telephony via VIC/VWIC NIM modules + dual PVDM3 DSPs: FXS station ports, FXO PSTN trunk lines, E&M PBX tie connections, fractional T1/E1 PRI multi-flex voice trunks
3. T.38 real-time fax over IP, fax passthrough, store-and-forward fax routing
4. DSP-accelerated voice codecs: G.711, G.719, G.729a, G.726, wideband G.722 high-fidelity audio, video conferencing codec support
5. Enterprise telephony tools: Scalable multi-site dial plans, voice hunt groups, toll bypass to eliminate long-distance PSTN charges
6. CME embedded call manager, SRST survivable remote telephony, Unity Express voice mail/auto-attendant hosted via ISC SSD storage modules

Integrated Security Suite (Activated via SL-4300-SEC-K9 License)

1. Zone-Based Stateful Firewall (ZBFW): Deep Layer 7 application inspection for HTTP, HTTPS, SIP, FTP, DNS, and enterprise business protocols
2. IOS IPS inline intrusion prevention: Signature-based threat detection, automated packet drop/reset, centralized threat logging
3. Hardware-accelerated VPN stack: AES-256/3DES IPsec site-to-site tunnels, DMVPN hub-spoke overlay networks, SSL VPN remote client access, GETVPN
4. AAA security framework: Local/RADIUS/TACACS+ authentication, authorization, accounting logging for audit compliance
5. Threat mitigation: Anti-DDoS policing, control-plane protection, URL filtering, malware traffic inspection
6. FIPS 140-2 Level 2 compliant with optional physical security shield kit for government regulated deployments

QoS & WAN Optimization

• Base QoS: CBWFQ, weighted fair queuing, per-interface traffic shaping, strict priority queuing for real-time voice/video traffic
• Advanced QoS (SL-4300-DATA-K9 license): LLQ low-latency queuing, DSCP marking/classification, NBAR2 next-generation application-aware traffic prioritization
• WAN optimization (SL-4300-AX-K9 license): WAAS bandwidth deduplication, compression, traffic shaping for long-distance branch links
• Link efficiency: LFI link fragmentation, cRTP VoIP header compression to eliminate voice jitter on low-speed DSL/ISDN backup lines

Management & Automation

• Triple out-of-band management interfaces: RJ45 Serial Console, Mini-USB Console, AUX dial-in modem port for emergency offline IT maintenance
• Secure remote management: SSHv2, HTTPS, SNMP v1/v2c/v3, TR-069 zero-touch automated provisioning
• Graphical management: Cisco Configuration Professional (CCP), DNA Center SD-WAN orchestration, vManage Viptela SD-WAN controller
• File management: AutoInstall remote IOS/image deployment, CompactFlash dual boot redundancy, USB config backup/restore
• Monitoring: Persistent syslog logging, NTP time synchronization, real-time CPU/memory/throughput telemetry export
• Cisco EnergyWise: Intelligent power control for attached IP phones, switches, and wireless access points

4. Typical Deployment Scenarios

1. Medium enterprise SD-WAN + voice branch gateway: Dual NIM slots for VDSL2 primary broadband + 4G LTE cellular backup, shared SFP fiber uplink for metro Ethernet WAN, dual PVDM3 DSP modules supporting 150+ concurrent IP phones, embedded DMVPN connecting branch to corporate data center, zone firewall + IPS for LAN security, centralized DNA Center policy orchestration.
2. Multi-location retail headquarters voice router: ADSL2+ NIM primary WAN, NIM-4GE EtherSwitch module for in-store POS/PC/Wi-Fi access, CME embedded call processing for up to 150 on-site IP phones, ISC SSD for Unity Express unified messaging, PCI DSS compliant security suite for payment card environments.
3. Medium agency remote office edge router: SFP fiber uplink for high-speed metro Ethernet, 100 Mbps performance license upgrade for heavy cloud/SaaS traffic, SSL VPN for remote employee access, WAAS bandwidth optimization via ISC SSD module for limited-capacity inter-office links.
4. Enterprise networking training lab core router: Modular NIM expansion for DSL, T1/E1, and cellular WAN training, dual PVDM voice DSP slots for full VoIP curriculum labs, dual console ports for simultaneous student management, complete IOS XE routing/voice/security/SD-WAN feature set aligned with enterprise certification curricula.

5. Standard Package Contents of ISR4321/K9

Separately Sold Optional Accessories

• NIM modular WAN/switch/cellular interface cards (ADSL/VDSL/T1/E1/4G LTE/EtherSwitch)
• PVDM3 DSP voice compression modules for VoIP, wideband audio and T.38 fax relay
• ISC internal MSATA SSD storage modules for WAAS / SRE virtualization workloads
• DRAM memory upgrade DIMMs (4GB / 8GB matched dual pairs)
• CompactFlash high-capacity spare cards
• SFP fiber transceivers (GE-SX/LX/ZX for fiber uplink connectivity)
• External PoE power injectors for non-PoE IP phones and wireless access points
• External redundant power supply (RPS) unit for mission-critical branches
• FIPS physical security shield kit for FIPS 140-2 Level 2 certification
• Permanent performance upgrade license (50 Mbps → 100 Mbps throughput boost)
• SL-4300-SEC-K9 security add-on license bundle
• SL-4300-UC-K9 unified communications voice license bundle
• SL-4300-AX-K9 advanced services WAAS/virtualization license bundle

Software Licensing Information

1. SL-4300-DATA-K9 (Base Data License)
   Core routing, dual-stack IPv6, MPLS, advanced QoS, NBAR2 application classification, native SD-WAN base functionality, EnergyWise power management, basic NAT/VLAN switching features.
2. SL-4300-SEC-K9 (Security Add-on License)
   Zone-based stateful firewall, IOS inline IPS, full AES/3DES IPsec/SSL/DMVPN encryption, advanced threat mitigation, anti-DDoS policing, FIPS crypto support.
3. SL-4300-UC-K9 (Unified Communications License)
   CME/SRST embedded voice call processing, Unity Express voice mail, full wideband VoIP codec support for PVDM3 DSP modules.
4. SL-4300-AX-K9 (Advanced Services License)
   WAAS WAN bandwidth deduplication optimization, SRE virtualized application hosting, centralized DNA Center advanced orchestration, high-volume logging and traffic analytics.
   Embedded onboard K9 crypto hardware complies with US ITAR export regulations for global shipment.

Short Commercial Catalog Summary