Mikael As you have not been completely happy with the answers so far, let me try to help.
1588v2 can (and usually does) run over UDP/IP (although it has other transport options, including a pure Ethernet one with Ethertype 88F7). So why do we need 1588 instead of NTP which has been around for a long time ? 1588 has an advantage when there is support from the network elements it traverses, and this happens in Ethernet switches. To date, there aren't routers that provide on-path 1588 support (your "new compliant hardware"), and so there is little reason to prefer 1588. In fact, there are multiple reasons to prefer NTP in such cases (security, scalability, bandwidth consumption, ...). The 1588-2008 standard is available from the IEEE. The Q13/15 work in the ITU has produced the G.826x series of Recommendations, that are available from the ITU-T web site. Contributions to Q13 are only visible to those with a TIES password. There IS a 1588 wikipedia entry - http://en.wikipedia.org/wiki/Precision_Time_Protocol and much more material available on-line (e.g., John Eidson's tutorial). Y(J)S -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Mikael Abrahamsson Sent: Wednesday, July 14, 2010 08:45 To: [email protected] Subject: [TICTOC] sync over IP Hello. I'm a router guy. I work for a mobile phone operator, we've been in the mobile phone and IP business for ~20 years. We're running GSM, UMTS and now deploying LTE. Our network also carries a lot of IP traffic for commerical and residential customers, mostly Internet traffic but we're also using MPLS L3 VPNs to provide L2/L3 services to our customers, mostly L3 VPNs. We're going all-IP for all the mobile services, meaning we want to carry everything over IP, including sync and circuit switched calls. This has made me a bit interested in sync over IP (since I've also been using NTP for 15+ years). I read the charter and it seems to indicate that this WG is trying to standardize sync over IP. When I look at the last years communication on this list I see a lot of reference to 1588v2 and SyncE. When I look at these I keep seeing references to "ethernet switch" in the diagrams, not IP routers. I also see lots of references to new "compliant hardware" being announced. This worries me. As an IP operator, we prefer to do routing as far out in the network as possible, as we've had bad experience with large L2 switching domains. We also prefer to keep our equipment for as long as possible, so any new service we deploy should work over existing infrastructure with devices that might be 10 years old. Deploying new IP/MPLS core/distribution hardware to support the new services is something we do not want to do. I've been trying to understand the network requirements of 1588v2 but come up short. There is no 1588v2 article on wikipedia at all. So I guess my question is if someone could please point me in the right direction, where can I find a primer for "sync over IP for a router guy" to make me better understand what's happening here? -- Mikael Abrahamsson email: [email protected] _______________________________________________ TICTOC mailing list [email protected] https://www.ietf.org/mailman/listinfo/tictoc _______________________________________________ TICTOC mailing list [email protected] https://www.ietf.org/mailman/listinfo/tictoc
