Home | Articles | About | Contact | Forum |
Friday, September 20, 2019

Lunarpages.com Web Hosting

Mailing List

By Joining the mailing list you will be notified of site updates.

Show Your Support For
This Site By Donating:

Audience: System Admins - Experts
Last Updated: 5/17/04 8:13 PM
Original Creation Date: 1/06/04 3:35 PM
**All times are EST**

BITS - Building Integrated Timing Supply

By Erik Rodriguez

This article describes the method of timing signal used to synchronize a hierarchy of network tier devices. This is only used by large-scale providers such carrier providers and ISPs.


The timing I am referring to in this article is specific to carrier devices that are used by ISPs The timing is important because it provides an alignment of data traveling through multiple devices that send and receive data. "Timing" refers to systematic electrical pulses that keep the "bit rate" of data constant. If the timing is incorrect, the data will not move through these devices correctly. The most accurate clocks we have today are generated and controlled by GPS satellites. Central offices and data centers receive data from these satellites to maintain a "correct" timing value for network devices. These devices are also used with wireless towers and DSLAMs. These signals are received using roof-mounted antennas (and sometimes small satellite dishes) that send the signal to a receiver. See the image below:

After the signal is received from the antenna, it is transmitted to a highly accurate timing device know as a BITS (Building Integrated Timing Supply) clock. Some devices (such as multiplexers) will contain their own BITS. In other cases, a master BITS will receive all the timing data and distribute it among the rest of the timing dependent devices. This is a master-slave relationship know as loop timing. SONET and other connections will use the timing provided by a BITS. The image below shows a BITS card used in Nortel, Lucent, and Alcatel equipment:

Timing devices are classified by the type of clock they use. These special clocks using crystal oscillators are known as Stratum clocks. The composition and design of these clocks are quite complicated. You can find very technical specs here.

BITS play a key role in the operation of a SONET network. Without accurate timing, SONET would be unable to correctly multiplex the data traveling through it.
Juniper SRX anti-spam filtering config
Windows Server 2008 Clustering Configuration
Windows 2008 R2 Network Load Balancing (NLB)
Extreme Networks: Downloading new software image
Juniper SRX save config to USB drive
Juniper SRX logout sessions
Extreme Networks Syslog Configuration
Command line drive mapping
Neoscale vs. Decru
Data Security vs. Data Protection
Juniper SRX Cluster Configuration
HOWTO - Create VLAN on Extreme Switch
Using a Non-local Colocation Facility
Linux Server Administration
IT Chop Shops
Flow Viewers: SFLOW, NetFLOW, and JFLOW
Exchange 2007 Back Pressure
IPtables open port for specific IP
Politics in IT Departments
HOWTO - Block Dropbox
Cisco IOS Cheat Sheet
Subnet Cheat Sheet
Design a DMZ Network
How DNS works
Firewall Configuration
Juniper SSG Firewalls
Server Management
Configuring VLANs
Runlevels in Linux
Server Clustering
SONET Networks
The Red Hat Network
Server Colocation
Complicated Linux Servers
Dark Fiber
Data Center Network Design
Firewall Types
Colocation Bandwidth

Copyright © 2002-2016 Skullbox.Net All Rights Reserved.
A division of Orlando Tech Works, LLC
By using this site you agree to its Terms and Conditions.
Contact Erik Rodriguez