A comparison of Network Simulation and Emulation Virtualization Tools

2.4. Supported protocols 
Both PT and GNS3 are used to help train learners in both fundamental networking principles and 
complex routing protocols. In design PT and GNS3 are extremely beneficial for network 
simulation, which enables an engineer to simulate a network environment that closely mimics a 
production network. Since GNS3 is an emulation software that uses real Cisco IOS Images and 
can connect the simulated devices to virtual computer systems, depending on the IOS image 
deployed most protocols in different network layers could be supported. On the other hand, PT 
only supports a subset of protocols that is shown in Table 1 [9]. 
Table 1. PT Supported Protocols 
Layer 
PT Supported Protocols 
Application 
FTP , SMTP, POP3, HTTP, TFTP, Telnet, SSH, DNS, DHCP, NTP, 
SNMP, AAA, ISR VOIP, SCCP config and calls ISR command support, 
Call Manager Express 
Transport 
TCP and UDP, TCP Nagle Algorithm & IP Fragmentation, RTP 
Network 
BGP, IPv4, ICMP, ARP, IPv6, ICMPv6, IPSec, RIPv1/v2/ng, Multi-
Area OSPF, OSPFv3, EIGRP, EIGRPv6, Static Routing, Route 
Redistribution, Multilayer Switching, L3 QoS, NAT, CBAL, Zone-based 
policy firewall and Intrusion Protection System on the ISR, GRE VPN, 
IPSec VPN, HSRP, CEF 
Network Access / 
Interface 
Ethernet (802.3), 802.11, HDLC, Frame Relay, PPP, PPPoE, STP, 
RSTP, VTP, DTP, CDP, 802.1q, PAgP, L2 QoS, SLARP, Simple WEP, 
WPA, EAP, VLANs, CSMA/CD, Etherchannel, DSL, ¾ G network 
support 
2.5. Supported commands 
Since GNS3 is an emulation software that uses real Cisco IOS Images, it has all the commands 
available to the specific installed IOS, and behaves as a real router would. On the contrary, PT is 
a software based simulator that only supports limited routing commands. More advanced 
optional parameters with commands may not be available. For example, PT has limitation in 
supporting the full suite of IPv6 commands. In addition, there are limited debugging capabilities, 
and often the output of extant debugging tools is limited and generic in nature. The environment 
is often limited to basic implementation of networking features and limited internal dynamic 
routing protocols, offering little to no support for external protocols such as BGP. Additionally 
commands that need access to external services may be limited to local testing only, such as the 
inability to implement AAA security to an external RADIUS or TACACS server. 

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