ATM Networks and Security

by Dr. Eva Bozoki - May 30, 2000

ATM Networks and Security
1. Introduction
2. ATM Connections
3. ATM Protocol Basics
4. Attacks
5. Security Measures
6. Placement of the User Plane Security Services
7. Secure Call Setup Protocol
8. Conclusion
Acknowledgement
References
About the Author

6. Placement of the User Plane Security Services

In considering the placement of user plane security services, it is important to evaluate the impact of the different locations. Placing the services in or below the ATM layer would require the encryption of the whole cell (header and payload), thereby degrading the switch performance. This would also expose the payload because the switches would have to decrypt and encrypt the cell. The complexity of key management also would be increased because the switches would require encryption/decryption keys. In addition, if the security services were placed in the physical layer, they would have to operate at ATM line speed (in order to deal with invalid and idle cells in addition to the valid cells).

By placing the user plane security services in the AAL layer, the lower-level headers would be transmitted in the clear; therefore, this solution does not provide flow confidentiality. In addition, because AAL is usually implemented as a single unit, no interfaces exist where the security services could be incorporated.

Placing the user plane security services above the AAL layer, the security services would have to be adopted for each higher layer (above AAL), thus multiplying the implementation effort.

This leaves the only suitable solution: The security services must be situated between the AAL and the ATM layers.