As the Packet Tracer network simulator from Cisco has been designed to help CCNA students go through a course, we cannot expect to work it with all stuff what is beyond of CCNA. Therefore I found really frustrated to make few configurations from LAB into PT, spending hours to figure out that is not possible to implement them.
The list of limitations of Packet Tracer 5.3.3 is from my digging over the Internet and from my own experience, especially when I tried employ Frame Relay with back-to-back routers and OSPF.
PACKET TRACER LIMITATIONS
Lack of commands:
R1(if-config)#frame-relay intf-type dce
R1(if-config)#no frame-relay inverse-arp
R1(config)#router ospf 1
The last line is used to explicitly define that the neighbouring routers are on non-broadcast network.
- No support for manual summarisation through area…range
- Cannot change the default reference bandwidth
- Cannot change default load balancing options
- No support for specifically debugging OSPF packets and hellos
- Cannot change default hold time
- Using variance does not place matching FS routes into the routing table
- No support for key chains
- Does not support sequence numbers
- Does not support Etherchannel on access layer switches
- Screws up STP port states quite often, leading to loops
For more reference about back-to-back & OSPF problems in Packet Tracer please see Cisco documentation below to compare what you can do on a physical equipment: