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section5-21.txt
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Terrestrial Wideband Network
_A_d_d_r_e_s_s:
Terrestrial Wideband Network
c/o BBN Systems and Technologies Corp.
10 Moulton St.
Cambridge, MA 02138
Attn: Karen Seo
_E-_m_a_i_l: wbhelp@bbn.com
_P_h_o_n_e: (617) 873-3427 (Terrestrial Wideband Network hotline)
_D_e_s_c_r_i_p_t_i_o_n
The Terrestrial Wideband Network was built and deployed by
BBN STC as a part of the initial phase of the Defense
Research Internet (DRI). In May 1989, this network replaced
the Satellite Wideband Network, which had been in operation
for the previous 8 years. The Satellite Wideband was a
domestic 3 Mbit/sec network that had been used for research
into the use of packet satellite technology to efficiently
support applications with varying delay, throughput, and
reliability requirements, e.g., interconnection of distri-
buted operating system clusters, development of end-to-end
bulk transfer protocols, multimedia conferencing, intercon-
nection real-time interactive simulation/training systems.
The Terrestrial Wideband continues this tradition by using
one of the cross-country T1 trunks from the DARPA National
Networking Testbed (NNT) to support research in high speed
networking, to provide connectivity among academic and
government sites, and to support a testbed for Internet pro-
tocol development and experimentation with applications.
Currently this network is carrying cross-country Internet
datagram traffic associated with DARPA-funded projects. It
also supports a research environment for multimedia con-
ferencing and voice/video conferencing using gateways which
use a real-time connection oriented protocol over a connec-
tionless network.
_________________________
The information in this section is provided in accor-
dance with the copyright notice appearing at the front
of this guide.
September 27, 1989 NNSC Section 5.21, Page 1
_N_e_t_w_o_r_k _A_c_c_e_s_s
Access to the Terrestrial Wideband is typically via an IP or
ST gateway. Connection of such a host is at the discretion
of DARPA. The current network includes the following Wide-
band Packet Switches (WPS) and user sites -- BBN (BBN), NY
(RADC), Washington (DARPA, NRL), Chicago (NCSA), LA (ISI),
SRI (SRI, Stanford). This fall, Ft Monmouth will be con-
nected to the NY WPS and CMU will be connected to a WPS to
be installed in Pittsburgh.
_W_h_o _C_a_n _U_s_e _t_h_e _N_e_t_w_o_r_k
The Terrestrial Wideband Network is to be used for DARPA-
funded research and development activities of the Internet
community. Users typically access the network via gateways
which have Internet connectivity to the Terrestrial Wideband
Network. Applications which might benefit most from the
Terrestrial Wideband Network are those which require high
bandwidth and/or low delay between geographically distant
sites, such as bulk file transfer, remote procedure calls,
conferencing, graphic simulations, and distributed operating
systems.
_M_i_s_c_e_l_l_a_n_e_o_u_s _I_n_f_o_r_m_a_t_i_o_n
a) System and Network Architecture
The Terrestrial Wideband is currently a trans-
continental network built on T1 trunks belonging to the
National Networking Testbed (NNT). The Wideband packet
switch nodes (WPSs) are located at unattended NNT
Points of Presence (POPs). They are based on Butterfly
multiprocessor hardware and are connected via the T1
fiberoptic trunks into a backbone configuration. The
WPSs pass network traffic using the Dual Bus Protocol
reservation scheme. Local area networks at user sites,
e.g., ethernets, are connected to the backbone packet
switches via Internet IP and ST gateways and T1 tail
circuits.
The current topology of the network, which resulted
from external constraints, is a series of packet
switches connected in a line by T1 trunks. This can
result in partitioning of the network in the event of a
packet switch failure. To minimize outages, the Ter-
restrial Wideband Network includes a number of
features. The multiprocessor hardware configuration
used for the packet switch provides redundancy in case
September 27, 1989 NNSC Section 5.21, Page 2
a processor node fails. Also, a failsafe box isolates
the WPS upon detection of an outage while continuing to
maintain connectivity between the T1 trunks in and out
of the failed WPS, thus maintaining network continuity.
The network also allows remote dial-in access for a
number of emergency functions that would otherwise have
to be performed by on-site staff.
b) Operations
A remote monitoring center provides network control
capabilities, and a dialup capability provides backup
monitoring and control when necessary. The Terrestrial
Wideband Network packet switch software can be updated
via remote downloading. Network operations support is
provided between 8AM and 8PM Eastern time.
c) Protocols
- TCP/IP traffic is supported by the Terrestrial Wide-
band Network. This is accomplished by using standard
Internet gateways.
- Stream Protocol (ST) protocol (based on IEN 119) is
used between gateways which support voice/video
traffic. This is a connection-oriented protocol which
operates over the connectionless Terrestrial Wideband
Network, and allows the gateways to send packets to
other destinations with minimal delay, as is required
for voice/video conferencing.
- Gateways communicate with the Terrestrial Wideband
Network packet switches (WPSs) via the Host Access
Protocol (HAP), specified in RFC 907-A. This is a pro-
tocol by which a host can send datagrams across the
network, and can request and manage network bandwidth.
- The WPS software provides an echo host which
responds to ICMP ping packets.
- Dual Bus Protocol provides a link-level transport
protocol which uses a reservation mechanism to provide
access fairness for each WPS. This is a type of Dis-
tributed Queue Dual Bus (DQDB) protocol similar to the
IEEE 802.6 Metropolitan Area Network (MAN) protocol,
but with features that support wide area networking and
multimedia conferencing. Whereas conventional packet
store and forwarding would involve per packet forward-
ing processing and buffering at every intermediate
September 27, 1989 NNSC Section 5.21, Page 3
node, a DQDB protocol performs processing and buffering
only at the entry point and minimizes the processing
and buffering at subsequent nodes along the trunk until
the exit point.
- Wideband Monitoring Protocol (IP protocol number 78)
is used between the WPSs and the monitoring center.
September 27, 1989 NNSC Section 5.21, Page 4