The Cisco 900 Series Integrated Services Routers are fixed-configuration branch routers that combine WAN connectivity, a four-port managed Gigabit Ethernet switch, security services, wireless LTE options, DSL access on selected models, and centralized management in a compact customer-premises platform.
They are designed for enterprise small branch offices and service-provider managed-service deployments. The platform supports secure broadband, Metro Ethernet, VDSL/ADSL, and LTE WAN connectivity, depending on the selected model. Each router includes integrated security and Cisco IOS software features for routing, firewalling, VPN, quality of service, application visibility, monitoring, and remote management.
Product positioning and deployment role
The 900 Series is suited to sites where a separate router, firewall, switch, and cellular backup device would add unnecessary hardware and management overhead. The fixed-configuration design simplifies standardization across branch locations while retaining support for multiple WAN types.
Typical deployment roles include:
- Small enterprise branch router and firewall
- Customer-premises equipment for managed Ethernet services
- DSL-based branch gateway
- LTE-enabled primary or backup WAN router
- Secure remote site with centralized configuration and monitoring
- Compact edge router for locations with limited rack or cabinet space
- Dual-WAN branch device using Ethernet and LTE or Ethernet and DSL
- Metro Ethernet demarcation and service-monitoring device
The platform includes separate console connectivity, one USB 2.0 Type A port, four managed Gigabit Ethernet LAN ports, and model-dependent WAN interfaces. The datasheet specifies a recommended user count of 50. This figure should be treated as a planning reference rather than a guaranteed concurrent-user or application-throughput limit.
The routers support multiple services simultaneously. The datasheet states that the platform can run multiple services with no performance degradation, but it does not provide a universal packet-forwarding, firewall, or aggregate WAN throughput figure. Presales sizing should therefore be based on the actual service mix, encrypted traffic volume, WAN rates, application behavior, and required security features.
SKU selection matrix
The following matrix consolidates the hardware models and LTE variants identified in the datasheet.
| SKU | WAN interfaces | LAN interfaces | LTE capability | DSL capability | Power arrangement | Best For |
|---|---|---|---|---|---|---|
| C921-4P | 2 x Gigabit Ethernet | 4-port GE managed switch | Not supported | Not supported | Internal power supply | Dual-Ethernet branch connectivity with internal AC power |
| C931-4P | 2 x Gigabit Ethernet | 4-port GE managed switch | Not supported | Not supported | Internal power supply | Ethernet-only branch routing with the C931 hardware designation |
| C927-4P | 1 x Gigabit Ethernet and 1 x VADSL | 4-port GE managed switch | Not supported | VDSL/ADSL2+ Annex A | External 12 VDC, 30 W adapter | Annex A DSL sites requiring Ethernet WAN fallback or dual access |
| C926-4P | 1 x Gigabit Ethernet and 1 x VADSL | 4-port GE managed switch | Not supported | VDSL/ADSL2+ Annex B/J | External 12 VDC, 30 W adapter | Annex B/J DSL deployments |
| C927-4PM | 1 x Gigabit Ethernet and 1 x VADSL | 4-port GE managed switch | Not supported | VDSL/ADSL2+ Annex M | External 12 VDC, 30 W adapter | Annex M DSL services |
| C921-4PLTEGB | 2 x Gigabit Ethernet | 4-port GE managed switch | LTE Category 4 | Not supported | Internal power supply | European, Middle Eastern, Mexican, or compatible Latin American LTE deployments |
| C921-4PLTEAU | 2 x Gigabit Ethernet | 4-port GE managed switch | LTE Category 4 | Not supported | Internal power supply | Australian and compatible LTE deployments |
| C921-4PLTEAS | 2 x Gigabit Ethernet | 4-port GE managed switch | LTE Category 4 | Not supported | Internal power supply | China, India, Southeast Asia, and compatible LTE deployments |
| C927-4PLTENA | 1 x Gigabit Ethernet and 1 x VADSL | 4-port GE managed switch | LTE Category 4 | VDSL/ADSL2+ Annex A | External 12 VDC, 30 W adapter | Annex A DSL with LTE backup or alternate WAN |
| C927-4PLTEGB | 1 x Gigabit Ethernet and 1 x VADSL | 4-port GE managed switch | LTE Category 4 | VDSL/ADSL2+ Annex A | External 12 VDC, 30 W adapter | Annex A DSL and European, Middle Eastern, Mexican, or compatible LTE |
| C927-4PLTEAU | 1 x Gigabit Ethernet and 1 x VADSL | 4-port GE managed switch | LTE Category 4 | VDSL/ADSL2+ Annex A | External 12 VDC, 30 W adapter | Annex A DSL with Australian or compatible LTE |
| C927-4PMLTEGB | 1 x Gigabit Ethernet and 1 x VADSL | 4-port GE managed switch | LTE Category 4 | VDSL/ADSL2+ Annex M | External 12 VDC, 30 W adapter | Annex M DSL combined with LTE connectivity |
| C926-4PLTEGB | 1 x Gigabit Ethernet and 1 x VADSL | 4-port GE managed switch | LTE Category 4 | VDSL/ADSL2+ Annex B/J | External 12 VDC, 30 W adapter | Annex B/J DSL combined with LTE connectivity |
All listed models include one integrated USB 2.0 port. The datasheet does not identify the USB port as a general-purpose external-device interface; supported USB uses are restricted to devices specified in the applicable Cisco documentation.
No PoE capability or PoE power budget is specified in the datasheet. The four Gigabit Ethernet ports should therefore not be quoted as PoE ports or used to power access points, phones, cameras, or other powered devices without separate validated documentation.
WAN and LTE engineering considerations
Ethernet-only models provide two Gigabit Ethernet WAN ports. These are appropriate where the site has two Ethernet handoffs, or where one Ethernet interface is used as a primary connection and the second supports failover, load balancing, or a separate service.
DSL models provide one Gigabit Ethernet WAN port and one VADSL interface. The supported DSL annex must be matched to the service-provider access network:
- C927 models support Annex A unless the model is the Annex M variant.
- C927-4PM supports Annex M.
- C926 models support Annex B/J.
- The platform supports multimode VDSL2 and ADSL2+ over Annex A, B, J, and M.
- Traditional G.DMT and T1.413 are also supported.
- VDSL2 support includes PSD profiles up to 17a/b, spectral shaping, vectoring, G.INP, physical-layer retransmission, SRA, Bitswap, and impulse-noise protection functions.
- Remote DSL management supports TR-069 and CWMP.
The LTE models use Cisco LTE 2.5 with a WP7600 series modem form factor. Theoretical Category 4 rates are 150 Mbps download and 50 Mbps upload. These are radio-category rates, not guaranteed application throughput. Actual service depends on carrier configuration, signal quality, spectrum, congestion, antenna placement, and subscription profile.
The LTE variants support a single micro SIM card socket compliant with ISO-7816-2 mechanical requirements. LTE functions include:
- MIP profile configuration
- Remotely initiated data callback using voice
- Remotely initiated data callback using SMS
- Remote firmware upgrade over LTE
- SIM lock and unlock
- SMS transmission and reception up to 160 characters
- Cellular multihoming support
- Auto SIM carrier capability with correct firmware selection
One multiband swivel-mount dipole antenna, part number LTE-ANTM-SMA-D, is included with each Cisco LTE 2.5 platform. The datasheet recommends ordering a second LTE-ANTM-SMA-D option for improved 2×2 MIMO coverage.
LTE regional band planning
The LTEGB group supports bands 1, 3, 7, 8, 20, and 28:
- FDD 700 MHz, band 28
- FDD 800 MHz, band 20
- FDD 900 MHz, band 8
- FDD 1800 MHz, band 3
- FDD 2100 MHz, band 1
- FDD 2600 MHz, band 7
The LTEAS group supports bands 1, 3, 5, 8, 40, and 41:
- FDD 850 MHz, band 5 CLR
- FDD 900 MHz, band 8
- FDD 1800 MHz, band 3
- FDD 2100 MHz, band 1
- TDD 2300 MHz, band 40
- TDD 2500 MHz, band 41
The LTEAU group supports bands 1, 3, 5, 7, 8, and 28:
- FDD 700 MHz, band 28
- FDD 850 MHz, band 5 CLR
- FDD 900 MHz, band 8
- FDD 1800 MHz, band 3
- FDD 2100 MHz, band 1
- FDD 2600 MHz, band 7
LTEGB is identified for Europe, Mexico, and the Middle East with specific bands and frequencies. LTEAU is identified for Australia. LTEAS is identified for China, India, and Southeast Asia. Latin American use is dependent on the specific operator supporting the listed bands.
Presales rule: confirm the carrier, service area, supported bands, SIM requirements, and antenna placement before selecting an LTE SKU. Regional suffixes must not be treated as interchangeable.
Routing, switching, and security
The Cisco IOS feature set includes common IPv4 and IPv6 routing functions, including RIPv1, RIPv2, OSPF, BGP, EIGRP, VRF Lite, GRE, MGRE, NHRP, BFD, PfR, NAT, DHCP server, relay and client functions, dynamic DNS, DNS proxy, DNS spoofing, ACLs, multicast, WCCP, L2TP, and L2TPv3.
The four-port managed switch provides:
- Auto MDI-MDX
- Up to 25 802.1Q VLANs
- MAC filtering
- SPAN
- Storm control
- Smart ports
- Secure MAC address functions
- IGMPv3 snooping
- 802.1X
Security functions include a zone-based policy firewall, VRF-aware stateful inspection, transparent firewall operation, application inspection and control, control-plane policing, flexible packet matching, network foundation protection, SIP application-layer gateway, authentication proxy for HTTPS, FTP, and Telnet, and firewall stateful failover.
VPN capabilities include SSL VPN, hardware-accelerated DES, 3DES, AES 128, AES 192, and AES 256, PKI, up to 50 IPsec tunnels, Easy VPN client and server, NAT transparency, DMVPN, GET VPN, VRF-aware IPsec, IPsec over IPv6, and FlexVPN.
The SEC and SEC-NPE licenses provide up to 250 Mbps of IPsec performance. This is the only explicit performance figure provided for encrypted traffic. It should not be interpreted as a general throughput rating for all services.
Quality of service and application control
QoS features support branch applications that require classification, prioritization, shaping, policing, and traffic conditioning. Available functions include LLQ, WFQ, CBWFQ, CBTS, CBTP, PBR, CoS-to-DSCP mapping, CBWRED, NBAR, LFI, RSVP, cRTP, DiffServ, QoS preclassify, QoS prefragmentation, and HQoS.
Application visibility and control are provided through NBAR2, Flexible NetFlow, and Performance Agent. The APP license adds advanced networking and application functions, including PfRv3, NBAR2, AVC, and IP SLA Initiator.
Presales rule: where the branch carries voice, video, or business-critical applications across a constrained DSL or LTE service, include a QoS design covering classification, WAN shaping rate, priority queues, and failover behavior. The datasheet lists the available tools but does not define a default QoS policy.
Management and availability
Management options include Cisco Configuration Professional, Cisco Configuration Express, Cisco Configuration Engine support, AutoInstall, IP SLA, Embedded Event Manager, Cisco Security Manager, CLI, HTTP, Telnet, SSH, SNMPv3, RADIUS, TACACS+, and Cisco Next Generation Plug-and-Play Protocol.
For WAN verification and operational monitoring, the platform supports Ethernet OA&M, Ethernet LMI, and IP SLA for Ethernet. IP SLA can also be used to monitor reachability and service quality across primary and backup paths.
High-availability mechanisms include VRRP, HSRP, and MHSRP. Redundant WAN connections can be used for failover protection and load balancing. These protocols provide gateway or path resilience, but the overall design must also consider carrier diversity, power availability, upstream equipment, and application session behavior.
Software licensing
| Part number | License | Principal capabilities | Best For |
|---|---|---|---|
| SL-900-IPB | IP Base, default | Routing protocols, ACL, NAT, QoS, BFD, VRF Lite, IP SLA Responder | Standard routing and branch connectivity |
| SL-900-APP(=) | Application Experience | IP Base plus L2TPv3, MPLS, PfRv3, NBAR2, AVC, IP SLA Initiator, LISP, VPLS, Ethernet over MPLS | Application-aware routing and advanced WAN services |
| SL-900-SEC(=) | Security | IP Base plus zone-based firewall, IPsec VPN, DMVPN, FlexVPN, GET VPN, SSL VPN; up to 250 Mbps IPsec performance | Secure branch WAN and encrypted site connectivity |
| SL-900-SECNPE(=) | Security with No Payload Encryption | Security feature package without payload encryption | Environments requiring the non-payload-encryption image |
The universal image part number is SISR900UK9-1583MB(=). The non-payload-encryption image is SISR900NPEUK9-1583MB(=). The universal image covers the listed C921, C931, C927, C927-4PM, C926, and LTE variants.
Physical, environmental, and power specifications
The C921-4P, C931-4P, and C921-4PLTEXX chassis measure 1.70 x 9.0 x 9.5 inches, or 4.32 x 22.86 x 24.13 centimeters, height by width by depth, including rubber feet.
The C927-4P, C927-4PM, C926-4P, C927-4PLTEXX, C927-4PMLTEXX, and C926-4PLTEXX chassis measure 1.10 x 10.20 x 7.00 inches, or 2.80 x 25.91 x 17.78 centimeters, including rubber feet.
Maximum weight is 2.65 pounds, or 1.20 kilograms.
LED indicators include:
- One green LED per Ethernet interface
- Two green DSL LEDs for CD and data
- One bicolor LTE RSSI LED
- One green LTE SIM/activity LED
- VPN status
- System OK status
Power characteristics are:
- Universal AC input from 100 to 240 VAC
- Frequency range of 50 to 60 Hz
- Internal power supply for C921-4P, C931-4P, and C921-4PLTEXX
- External 12 VDC, 30 W adapter for C927-4P, C927-4PM, C926-4P, C927-4PLTEXX, C927-4PMLTEXX, and C926-4PLTEXX
The specified nonoperating temperature range is -40 to 70 degrees C. Nonoperating humidity is 5 to 95 percent relative humidity, noncondensing. Nonoperating altitude is 0 to 15,000 feet, or 0 to 4570 meters.
Operating temperature is:
- C921-4P and C931-4P: 0 to 50 degrees C
- C927-4P, C926-4P, C927-4PM, and C921-4PLTEXX: 0 to 45 degrees C
Operating temperature derates by 1 degree C per 1000-foot increase in altitude. Operating altitude is 0 to 10,000 feet, or 0 to 3000 meters. Operating humidity is 5 to 95 percent relative humidity, noncondensing.
The datasheet does not specify MTBF values. It also does not specify acoustic noise, fan speed, sound pressure level, or sound power level. Acoustic planning should therefore use the installation environment and the actual hardware configuration rather than an assumed noise rating.
Mounting and installation
ACS-900-RM-19(=) is the rack-mount kit for the C921-4P, C931-4P, and C921-4PLTEXX models.
ACS-900-DM(=) is the under-the-desk mount kit for the listed 900 Series models, including C921-4P, C931-4P, C927-4PLTEXX, C927-4PMLTEXX, and C926-4PLTEXX.
Presales rule: select the mounting kit at the same time as the router. The rack-mount option is not identified for the smaller C927 and C926 chassis in the supplied specifications.
Warranty and service considerations
The supplied datasheet does not state a standard hardware warranty period or a specific advance-replacement entitlement. Warranty terms must therefore be confirmed through the applicable purchase agreement and regional Cisco terms.
Cisco Smart Net Total Care technical support is available on a one-time or annual contract basis. Support options range from help-desk assistance to proactive onsite consultation. The stated support inclusions are:
- Major Cisco IOS software updates covering protocol, security, bandwidth, and feature improvements
- Full access rights to Cisco technical libraries for technical assistance, electronic commerce, and product information
- Twenty-four-hour access to Cisco technical support staff
Cisco and certified partner services cover planning and design, technical maintenance, performance troubleshooting, operational health, software application support, and optimization. Service selection should reflect the operating model: centralized enterprise support, provider-managed CPE, or branch environments with limited local IT resources.
Presales sizing rules
- Select the hardware by WAN technology and regional LTE band requirements first.
- Treat the recommended 50 users as a reference point, not as a throughput guarantee.
- Do not quote PoE; no PoE ports or power budget are specified.
- Size encrypted traffic separately because the SEC package specifies up to 250 Mbps IPsec performance.
- Validate LTE carrier bands and coverage before selecting LTEGB, LTEAU, or LTEAS.
- Order a second LTE antenna where improved 2×2 MIMO coverage is required.
- Match DSL Annex A, Annex B/J, or Annex M to the provider service.
- Include the required software license for firewall, VPN, application visibility, or advanced WAN features.
- Confirm power type and mounting requirements before finalizing the bill of materials.
- Do not use MTBF or acoustic assumptions because those values are not provided in the datasheet.