[afnog] Juniper MX "timing support" = ?

[Mark Tinka]

On Wednesday, January 07, 2015 07:49:29 AM Frank Habicht 
wrote:

> While it seems to smell a bit like SDH, I'd appreciate
> more hints, pointers or confirmation about what the
> "timing support" means and does.

Timing, in IP or Ethernet equipment, refers to being able to 
provide timing (or to be more precise, clocking signals) 
across a packetized network.

As you know, services such as TDM-based voice and circuit-
switch data networks rely heavily on clocking to ensure a 
proper service delivery.

In the last 7x or so years, pretty much every type of 
communications service has been moving to packet (be it over 
IP or over Ethernet, or both), due to better scaling 
properties of packetized networks. As such, traditional 
service providers needed packetized networks to provide 
timing support in order to consider removing legacy 
infrastructure, e.g., an IP router providing data services 
to a GSM base station.

In came SyncE (Synchronous Ethernet), which essentially 
enables the transmission of clocking signals across an 
Ethernet network:

	http://en.wikipedia.org/wiki/Synchronous_Ethernet

The other option is PTP (Precision Time Protocol) also known 
as 1588 (IEEE 1588, to be exact), meant to be a serious 
improvement from NTP- and GPS-based timing.

	http://en.wikipedia.org/wiki/Precision_Time_Protocol

All network equipment vendors (Cisco, Juniper, ALU, Brocade, 
e.t.c.) all have some kind of Timing support in some of 
their products.

For your case, all modular MX80 chassis' support SyncE, but 
PTP/1588 is only supported on the -T models due to the -T 
models having a better quality oscillator.

The only non-modular MX80 chassis' that support timing are 
those of the -T model.

Use-case? Well, say a GSM operator in Tanzania wanted to 
migrate their entire backbone from legacy protocols to 
IP/Ethernet, and wanted to use you, Frank, as their 
provider. GSM services carry voice, and as such, rely 
heavily on clocking. In order for them to be truly "next-
generation" (yuck!), they would request you to provide 
timing support to their base stations as part of the overall 
IP/Ethernet conversion project. This is where you would 
engage the capabilities of your MX80 (or whatever other 
router/switch you have that supports SyncE or 1588) to pass 
clocking signals across the packet links you'd deliver to 
your customer.

In practice, nobody really does this. The idea is great but 
I'm yet to find a legacy operator willing to entrust their 
clocking requirements to a 3rd party provider :-). So what 
normally happens in real life is that a legacy opertor will 
outsource the data traffic to a packet service provider 
(except pretty much all GSM operators today run an IP 
network of some sort or other), but mainatin clocking in-
house. Can't say I blame them - clocking is serious business 
especially for voice hand-off of mobile calls between base 
stations.

Hope this helps.

Mark.