Cisco 2900 series Integrated Services Router are the best in practice and ideal router for deployment in small and medium sized branch offices. Cisco 2900 Series has Cisco 2901, Cisco 2911 router, Cisco 2921 router and Cisco 2951 router in it. They deliver you the high secure video, voice, data and application services. These routers include the AAA feature of identity management for the authorization, accounting and authentication of incoming traffic. The high level density feature of voice and video gives the support for Cisco Communication Manager Express and IP Telephony. They include embedded hardware for secured VPN connectivity using the Cisco IOS IPS, Cisco IOS Firewall and Cisco IOS Content Filtering.

Ethernet Ports
Cisco has manufactured 4 models Cisco 2901 ISR, Cisco 2911 ISR, Cisco 2921 ISR and Cisco 2951 ISR under the Cisco 2900 Integrated Services Router series. These routers are featured with the integrated 10\100\1000 Fast Ethernet and Gigabit Ethernet ports. Cisco 2901 ISR has 2 integrated 10\100\1000 Ethernet ports in it, while the other three models were designed with 3 integrated Ethernet ports in them. Which gives the users high connectivity and communication feature.
Ethernet Ports Comparison:
Feature | Cisco 2901 ISR | Cisco 2911 ISR | Cisco 2921 ISR | Cisco 2951 ISR |
10\100\1000 Ethernet Ports |
2 |
2 |
3 |
3 |
Power over Ethernet (PoE)
These routers were embedded with the fully integrated power distribution feature having the Power over Ethernet feature. Power over Ethernet (PoE) feature gives the users facility of using the Ethernet cable for Data Transmission as well as for passing Electrical Power. There is designed an LED labeled as PoE which blinks when PoE services are being used.
PoE Comparison
Feature | Cisco 2901 ISR | Cisco 2911 ISR | Cisco 2921 ISR | Cisco 2951 ISR |
Power over Ethernet |
Yes |
Yes |
Yes |
Yes |

WAN Interface Card slots
These routers are designed with the Investment Protection feature keeping in mind and there were designed 4 WAN Interface Card slots for future use. So that when required extra WIC cards may be installed on the same board.
WIC Slots Comparison:
Feature | Cisco 2901 ISR | Cisco 2911 ISR | Cisco 2921 ISR | Cisco 2951 ISR |
WAN Interface Card Slots |
4 |
4 |
4 |
4 |
DSP slots
Digital Signal Processor slots are also designed which provides high services for voice and video applications. Cisco 2901 ISR and Cisco 2911 ISR models have 2 DSP slots embedded in them while the other two models have the 3 DSP slots embedded in them. On some of the Cisco routers normally a hardware Packet Voice Digital Signal (PVDM) is required that provides the DSP resources to the connected system.
DSP Slots Comparison:
Feature | Cisco 2901 ISR | Cisco 2911 ISR | Cisco 2921 ISR | Cisco 2951 ISR |
DSP Slots |
2 |
2 |
3 |
3 |
Cisco IOS Firewall
IOS image installed in these routers has the feature of IOS content filtering which give you the security from the new and known internet threats that helps you keeping your data secure from internet viruses. Cisco IOS firewall feature keeps the network connectivity and security of data security from the other networks threats. IOS Network Address Translation (NAT) is enabled on the IOS image that helps you keeping two networks together. NAT can very simply be enabled on any router when translation is required.
Cisco IOS:
Feature | Cisco 2901 ISR | Cisco 2911 ISR | Cisco 2921 ISR | Cisco 2951 ISR |
Cisco IOS Content Filtering |
Yes |
Yes |
Yes |
Yes |
Authentication, Authorization, Accounting (AAA)
AAA is a security feature that gives you three most required security features in a very modular way. The authentication feature gives you the method for identifying the users try to logging in to the network and authorization level allows it access to the network after verification. The authorization process works on the list which keeps the data of users allowed to access that network. The accounting level gives you the method for collecting the server security information that is used for billing and for auditing which keeps record of all the users, all the configurations and the start and stop time of the system. The AAA feature of the IOS maintains the security level of network high. It authenticates, authorizes and accounts the incoming traffic to the network. This features is already enabled on these routers.
AAA Feature:
Feature | Cisco 2901 ISR | Cisco 2911 ISR | Cisco 2921 ISR | Cisco 2951 ISR |
Supports AAA Services |
Yes |
Yes |
Yes |
Yes |
Conclusion
Cisco 2900 series router are the best router for small and medium size businesses. If we compare between 2900 series routers they all have almost the same specifications and features. Cisco 2921 and Cisco 2951 have Gigabit Ethernet ports while 2901 and 2911 have don’t. So if we keep in mind future expansion in the network then we should prefer Cisco 2921 and Cisco 2951 router. Cisco 2921 and Cisco 2951 routers have greater number of DSP slots also than the other models of Cisco 2900 series.