@make[Report] @device(x2700) @Majorheading[DYNATECH] @section[General] Dynatech sell a range of X.25 equipment including PADs, switches and a Gateway Address Translator and a Network Control Centre. The switch is called Multi Switch X.25 and has been certified for use with most of the public data networks. @section[Hardware Description] The Multi Switch X.25 is based on a single 8 MHz 280 processor with 248 K bytes RAM. The basic switch consists of a box with power supply, a CPU board and two trunk boards each capable of handling two lines. A further 4 trunk boards can be installed in the box. @section[Software Description] 280 assembler is used throughout. @section[Configuration Options] The Model 12 comes with 4 ports, a further 8 ports may be added in pairs. @section[Line Speeds/Interface Options] The following internal clock rates are supported: @begin[verbatim] 1200, 2400, 4800, 9600, 19.2k and 57.6k @end[verbatim] Any line may be externally clocked up to 64 kb/s. V24, V35 and X.21 are supported. @section[Throughput] A minimum throughput of 100 data packets/sec through the PSE is claimed. @section[Costs] The model 12 costs @T{#}17,200 for 4 trunks with an additional @T{#}2,297 per additional trunk pair. @section[X.25 Facilities] Call statistics (as per PSS) are not provided. Packet and window negotiation is apparently supported but regardless of the values negotiated a call always gets the maximum figures that the switch is set up for. Packet sizes of 128 and 265 are 'supported'. A maximum of 127 logical calls per link are supported. @section[Multinode Networks] Dynatech use 'simple X.25' to communicate between multiple nodes on a network. There is a special marker on a trunk to indicate that the trunk, acting as a DCE, is connected to another switch and not to a simple DTE to allow network clearing codes to be passed between switches. Trunks may also be grouped together to allow load sharing (based on the smallest number of active calls) on multiple connections. @section[Addressing] A maximum of 16 entries is allowed for each trunk in the routing table. Single addresses as well as address with 'don't care' digits are allowed. A trunk may be either a DTE or a DCE although it is controlled by a strapping on the CPU board and therefore the switch must be powered off to change the setting. @section[Network Management] Dynatech use a software package on an IBM XT to create a Network Control Centre (NCC). The NCC can poll a number (?) of switches to read off statistics, note alarm conditions etc. It does not appear that detailed statistics are held for each call and as the machine is polling, alarms will only be noted at the poll rate which are from 1 hour to 4 hours in steps of half hours. The information when collected is stored on the PC's disc for late display or printing. The NCC uses a simple character stream running over X.29 to collect the information. For example, it would issue 'STAT 5' to receive link status for Line 5 in the same manner as an operator on the switch control console. This could be emulated by another machine. @section[Statistics] The Model 12 only collects information on - @begin[verbatim] number of Resets number of Data Packets number of CRC errors @end[verbatim] The statistics may be stored in the battery backed RAM to avoid loss. @section[Operator Control] Claimed to meet the spec - awaiting further information. @section[Date-Time Stamp] Not performed by the switch but can be provided by the NCC. @section[PSS Compatibility] Complies. @section[Performance - Packet Transmissions] @begin[verbatim] Call Request 11-20 ms Data <10 ms Clear 15 ms @end[verbatim] @section[Availability and Reliability] Claimed to meet the spec. The MTBF is calculated at 15,000 - 20,000 hours, experience with the equipment indicates a figure of 20,000 hours. @section[Operation] Complies; software is contained on ROM. @section[Reconfiguration] Configuration is performed 'on-line' or can be held in the NCC. The system needs to be re-booted to change either:- @begin[verbatim] a link from DTE to a DCE or Internal clock to external clock. @end[verbatim] @section[Known Problems] @begin[itemize] Although it is claimed the window and packet negotiation will work in reality a call always gets the maximum window and packet size that the switch is configured for even though the negotiation has apparently worked. When a line is configured as a DCE it does not poll to start the link up. This is not compatible with PSS and would cause problems with existing DTE implementations. A line is immediately restarted on losing control signals. This prevents the insertion of a line monitor in a link. Switch does not appear to have enough buffer space, it was easy to provoke it into putting RNR up with only 60 calls in use. As a DCE it doesn't poll after receiving an RNR from the DTE. @end[itemize] @section[X.25 (1984)] Dynatech say the are activly working on it and hope to have it ready for trialing in early 1986. @section[Academic Community Special Requirements] There is a seperate U.K. Software company that would be interested in doing converters and other special requirements for the community. The preferred vehicle would be the Dynatech 'MultiCom X.25' product which has a rather restrictive 9.6 kb/s maximum line speed. @section[Product History] The Model 12 was launched in the UK in November '84, there are currently 5 customers in the UK with twelve installed units. An additional order for 15 units has been placed bye one of the customers. It is estimated that 500 to 100 have been sold world wide. @section[Maintenance] It was suggested that a third party would be approached for maintenance if the Academic Community bought the product. @section[Company Information] Some development is done in the UK, in particular the 'Protopad' and 'Monopad' but all model 12 development is done in the USA. The Network Control Centre software is being done in the UK. The development team in the UK is 3 people.