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: [email protected]

           _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

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