Yaakov Stein wrote: > *From:* Xie Lei <mailto:[email protected]> > > *To:* [email protected] <mailto:[email protected]> > > *Sent:* Wednesday, August 26, 2009 9:50 AM > > *Subject:* [TICTOC] Adding the Femto Synchronization requirments in > requirement document > > > > > > Dear All > > As the agreement in IETF75# meeting, we decide to add the femto > synchronization requirements in requirement document. After checking the > requirement document, i think, the best way is to add a new section as > following: > > 3.2.1 Cellular Backhauling of Femtocells > > Femtocell application may use a portion of the public and private > network infrastructure to provide connectivity and backhaul service > between the femtocell device and gateway. The use of a public network > facility implies that some level of network security is necessary, as > compared to the scenarios presented in Section 3.1.1.x which assumed > that the connectivity and backhaul service is done over a private > network (eg., see Note (2)), typically for macrocell application. In > addition the number of femtocell devices can easily extend to hundreds > of thousands, much higher than the number of macrocells. The following > requirements should be considered for femtocell deployments: > > 1. The use of IPSec links in the public network could degrade the > transport of synchronization message and its performance. In order > to reduce the impact to synchronization when traversing secured > links, it is possible to leave some of the synchronization message > unprotected. Caution should take place on the use of IPSec and > synchronization performance
The use of IPSec *will* degrade any NTP packet and I don't expect that any TICTOC packet will be able to do better over IPSec. There is also the issue of the security part requiring each end to have accurate time in the first place defeats the purpose of this. > 2. Synchronization messages traversing Network Address Translation > (NAT) functions need to be considered in order to guarantee proper > connectivity between a Clock Server and the femtocell device NAT destroys the capability of any possibility of verifying the IP address of the sender. You need to disallow NAT devices or provide another way of passing the packets through the device. > 3. Scalability aspects (large number of femtocells), bandwidth > consumption of synchronization messages and the placement of clock > servers are to be considered as the network architecture is > developed. > NTP seems to have no problens with scalability so I cannot imagine what new issue would arise that what be any different. Danny -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. _______________________________________________ TICTOC mailing list [email protected] https://www.ietf.org/mailman/listinfo/tictoc
