This is a pdf about cisco 2921 router.

1. Cisco 2921 Specs
The Cisco 2921 router, supporting voice module, is designed for small offices.
Cisco 2921 Specs
Release Date: 13-OCT-2009
AC Input Voltage: 100 to 240 VAC auto ranging
Compact Flash (External) - Default: slot 0: 256 MB; slot 1: none
Maximum End-Point PoE Power Capacity with PoE Boost (Watts): 750
Airflow: Back and Side to Front
Temperature: 9,843 feet (3,000m ) Maximum Altitude : 32 to 77 F (0 to 25 C)
ISM Slots: 1
Modular LAN Switchports (with optional PoE): 50
Altitude: 10,000 ft (3,000m)
DC Input Voltage:
24 to 60 Vdc, autoranging positive or
negative
Compact Flash (External) - Maximum: slot 0: 4 GB; slot 1: 4 GB
Temperature: 13,123 feet (4,000m) Maximum Altitude : 32 to 86 F (0 to 30 C)
Cisco Unified SRST Sessions: 100
SFP-based ports (use of SFP port disables the corresponding RJ-45 port): 1
Memory DDR2 ECC DRAM - Maximum: 2 GB
Onboard DSP (PVDM) Slots: 3
Wall-Mount (refer to installation guide for approved orientation): No
Double-Wide Service Module Slots: 1
Power Supply: AC; PoE; and DC
Serial console port: 1
Acoustic: Sound Pressure (Typical/Maximum): 54.4/67.4 dBA
USB Console port (Type B) (up to 115.2 kbps) 1: 1
Maximum Power with PoE Power Supply (Platform Only) (Watts): 370
AC Input Current: 3.4 to 1.4A range (max AC power supply)
Maximum Power with DC-PoE Power Supply (Platform Only) (Watts): n/a
Dimensions (H x W x D):
3.5 x 17.25 x 18.5 in. (88.9 x 438.2 x 469.9
mm)
Rack Mounting Kit: Included
Weight with AC PoE Power Supply (No Modules): 30 lb (13.6 kg)
RPS Support (External): Cisco RPS 2300
EHWIC Slots: 4
Short-Term (per NEBS) Humidity : N/A
Cisco Unified CCME Sessions: 100
Typical Weight Fully Configured : 34 lb (15.5 kg)
External USB 2.0 Flash Memory Slots (Type A): 2

2. AC Input Surge Current: < 50A
Integrated WAN Ports: 3 GE; (1 SFP)
Non-Operating Temperature: -40 to 158 F (-40 to 70 C)
Relative Humidity: 10 to 85%
Acoustic: Sound Power (Typical/Maximum): 62.6/74.5 dBA
Temperature: Short-Term (per NEBS) 5906 feet (1,800m) Maximum
Altitude:
n/a
Temperature: 5,906 feet (1,800m) Maximum Altitude : 32 to 104 F (0 to 40 C)
Non-Operating Relative Humidity: 5 to 95%
Maximum End-Point PoE Power Available from DC PoE Power Supply
(Watts):
n/a
Weight with AC Power Supply (No Modules): 29 lb (13.2 kg)
Serial auxiliary port: 1
Embedded Hardware-Based Cryptography and Acceleration: Yes
RJ-45-based ports: 3
Optional Airflow Kit: n/a
Memory DDR2 ECC DRAM - Default: 512 MB
Typical Power (No Modules) (Watts): 60
DC Input Current: (MAX) 12A (24V); 5A (60V)
Total onboard WAN 10-100-1000 Ports: 3
Rack-Mount 19 in. (48.3 cm) EIA: Optional
AC Input Frequency: 47 to 63 Hz
Double-Wide EHWIC Slots: 2
Service Module Slots: 1
Rack Units: 2 RU
Non-Operating Altitude: 15,000 ft (4,570m)
Maximum End-Point PoE Power Available from AC PoE Power Supply
(Watts):
280
Maximum Power with AC Power Supply (Watts): 320
Cisco 2921/K9 supports expansion functions with modules and cards
① Compact flash 0 and 1 (0, right) ⑦ 10/100/1000 Ethernet port (GE 0/1 and GE 0/2)
② EHWIC 0,1,2 and 3 (0, far right) ⑧ 10/100/1000 Ethernet port GE 0/0
③ USB serial port ⑨ Ground
④ RJ-45 serial console port ⑩ USB 0 and 1 (1, top)
⑤ AUX port ⑪ Service module slots
⑥ SFP

3. Cisco 2921 VS Huawei
Vendor Product Description Huawei Advantages
CISCO CISCO2921
Cisco 2921 w/3 GE,4 EHWIC,3 DSP,1 SM,256MB CF,512MB
DRAM,IPB
HUAWEIAR2220
3GE WAN(1GE Combo), 2 USB, 4 SIC, 2 WSIC, 1 DSP Slot,
150W Power
Forwarding performance：1Mpps vs.
479Kpps
IO Slots: 2 WSIC vs. 1 SM
hot-swappable interface card
Source:http://www.cisco.com/c/en/us/products/routers/2921-integrated-services-router-isr/index.html
From https://howcisco.wordpress.com/