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SADISOPSG/14-WP/23/
International Civil Aviation Organization
WORKING PAPER / SADISOPSG/14-WP/23
28/04/09
SATELLITE DISTRIBUTION SYSTEM OPERATIONS GROUP (SADISOPSG)
FOURTEENTH MEETING
Bangkok, Thailand, 15 to 17 July 2009
Agenda Item / 10: / Any other businessHARDWARE REFRESH PROPOSAL FOR SADIS 2G UPLINK INFRASTRUCTURE
(Presented by the SADISProviderState)
SUMMARYThis working paper presents hardware refresh proposals for the SADIS 2G uplink infrastructure at Exeter and Whitehill, and outlines the associated costs.
1.INTRODUCTION
1.1The group will be aware that the SADIS second-generation broadcast system (SADIS 2G) has been in operation since November 2004, and became the sole satellite distribution servicein January 2009 following the cessation of the SADIS first-generation system (SADIS 1G). Owing to the rate of development within the telecommunications industry, and the fact that SADIS 2G hardware was installed in the months leading up to November 2004, a number of hardware components that are used as part of the SADIS 2G uplink infrastructure are now 5 years old, and are considered to be nearing or already at the end of their useful life. Consequently, it has become necessary for the SADISProviderState to assess whether integral components of the SADIS 2G uplink should be replaced or upgraded as part of a hardware refresh, and the associated costs that arise from such an undertaking.
1.2If a hardware refresh is not undertaken, firstly, support and maintenance costs become significantly more expensive and uneconomic. Secondly, a failure of a critical component could interrupt delivery of the SADIS service and leave the ProviderState in breach of its obligations under the SADIS Agreement.
1.3In parallel with considering the need for a SADIS 2G hardware refresh, the SADIS Provider State, in consultation with VADOS Systems, hasinvestigated whether the SADIS 2G uplink(i.e. hardware at Exeter and Whitehill, plus interconnection) could be simplifiedso as to have no detrimental impact on existing SADIS 2G users, butresult in improved service availability ratings.
1.4This working paper outlines the current SADIS 2G uplink infrastructure, reviews the costs involved to support and maintain the equipment, and makes recommendations for the groups consideration relating to a hardware refresh and simplified uplink topology.
2.existing SADIS 2G uplink infrastructure
2.1Figure A1 at Appendix Apresents a simplified topology of the SADIS 2G infrastructure. The uplink aspects of SADIS 2G are shown on the upper-half of the schematic, with the downlink segment in the lower-half.
2.2With regards uplink equipment, there are 4 key hardware components that ensure the WAFS and global OPMET data is delivered to the Intelsat 904 satellite without conflict or delay, namely:
i)Dual contingent MegaPAC 2003s at Exeter (called PAC1 and PAC2);
ii)Dual contingent MegaPAC-V’s at Whitehill (called PAC3 and PAC4);
iii)VadEDGE 4200 router with associated RF switch; and
iv)Dual contingent Comtech SDM-300A modems.
2.3Of the components listed at 2.2 above, the following are considered to be nearing or already at the end of their useful life.The mean time between failure (MTBF) figures for each of these components is shown in brackets:
i)MegaPAC 2003’sat Exeter(~42,000 hours or ~5 years); and
ii)MegaPAC-V’s at Whitehill (~45,000 hours or ~5 years);
These components were installed by VADOS Systems (formerly Satelcom) in 2004. Note that the MTBF figure shown for the MegaPAC-V relates to the lowest figure for an internal component – namely the XIO board. Other components within the MegaPAC-V, such as CPU and backplane, have MTBF figures ranging from 60,000 hours (7 years) to 200,000 hours (23 years).
2.4The VadEDGE 4200 and Comtech modems used in the uplink infrastructure at Whitehill have MTBF figures in the region of 60,000 hours (7 years) and 300,000 hours (or 35 years) respectively, and are therefore not yet considered to be ‘end of life’.
2.5As expressed in paragraph 1.1, SADIS 2G became an operational service in November 2004, although much of the uplink hardware used to support the service was installed in the months prior to this date. It is clear from studying the MTBF figures provided in 2.3 above that a number of key uplink components have already reached, or are near to reaching, the end of their useful life.
2.6SADIS 2G hardware and software used in the uplink infrastructure is supported and maintained by VADOS Systems under contract with the Met Office. VADOS Systems are a key supplier of SADIS system components and are well-versed with SADIS 2G and its predecessor SADIS 1G. VADOS has clearly stated to the Met Office that whilst they are under contract to provide hardware and software support for the SADIS 2G system in 2009 and 2010, if any hardware component that is considered to be ‘end of life’ was to fail (i.e. those components listed at paragraph 2.2), it could prove extremely difficult to source a replacement. Furthermore, VADOS will not be in a position to provide SADIS 2G support and maintenance beyond 31 December 2010 unless a hardware refresh of legacy components is conducted within the next 18 months.
2.7It is for these reasons that the SADISProviderState believes that a hardware refresh for SADIS 2G is essential to continue to meet its obligations to the SADIS Agreement. Opportunities exist to refresh existing hardware, including the simplification of the uplink topology and improving the system availability rating.
3.current availability and support costs for VADOS SADIS 2G uplink hardware
3.1VADOS equipment included in the existing SADIS 2G uplink network is shown at Figure A2 of Appendix A. SADIS 2G availability calculations (at March 2009) based on existing hardware infrastructure are illustrated by Figure A3 of Appendix A.
3.2From Figure A3, it is clear to see that the existing SADIS 2G uplink VADOS equipment has a 99.993323% system availability figure based on a mean time to repair (MTTR) of 4 hours. This figure improves to 99.999156% for equipment that has a 0.5 hour MTTR (i.e. using the VadEDGE 4200 hot standby unit).
3.3SADIS 2G support and maintenance provided by VADOS under contract with the Met Office in 2009 and 2010 is £36,918 per annum. As stated earlier, VADOS will not be in a position to provide equivalent support beyond 31 December 2010 unless a hardware refresh of legacy components is conducted within the next 18 months.
4.hardware refresh proposals and projected support costs
4.1In considering the options available for a SADIS 2G uplink hardware refresh, the SADISProviderState has paid due respect to:
i)a clear initiative of the Met Office IT Services to move away from a reliance on the legacy X.25 protocol withinthe next 15 to 18 months;
ii)advances in telecommunications hardware in recent years;
iii)ongoing support and maintenance costs, and risks to service resilience and availability in a ‘business-as-usual’ scenario; and
4.2Appendices B and C to this working paper presents two hardware refresh options for the group consideration. Option 1 presented in Appendix B is a like-for-like refresh, whilst Option 2 presented in Appendix C is a simplifiedSADIS 2G uplink topology.
OPTION 1 – Like-for-like refresh
4.3Figure B1 of Appendix B illustrates the Option 1 topology. Changes from the existing SADIS 2G uplink infrastructure are as follows:
i)2 new VadEDGE 4200’s replace the 2 MegaPAC 2003’s at Exeter;
ii)2 new MegaPAC V-IX’s replace the 2 MegaPAC V’s at Whitehill; and
iii)1 new VadEDGE 4200 replaces the ISDN MegaPAC at Whitehill[†].
4.4In addition to replacing the existing MegaPAC 2003 units at Exeter with VadEDGE 4200 units, two MegaPAC V’s at Whitehill would be replaced by two MegaPAC V-IX units.
4.5Each MegaPAC V-IX would have a single CPU and two power supply units (PSU’s). An X.21 link would still be required between each MegaPAC V-IX to provide alternate routing functionality. This link would be a simple wired connection and could be run at any speed (64K has been shown to reflect the current configuration). A VadEDGE 4200 would still be required between the two MegaPAC V-IX’s and the switch.
4.6At time of writing (March 2009), the current ISDN MegaPAC 2003, which connects into one of the MegaPAC V’s at Whitehill, is in the process of being replaced by a VadEDGE 4200 and BRI module to support the SADIS 2G data backup arrangement.
4.7The table below summarises hardware and installation costs associated with Option 1 (correct at March 2009 prices).
Table 1–Option 1 hardware refresh and installation costs (including options)
OPTION 1 / Cost (£)Requisite hardware[‡], comprising:
2*MegaPAC V-IX Base System Includes a Chassis, 1 CP6000, 2 PSUs, 1 Switch
6*Baffle and Panel set to blank out 3 slots
18*Single Panel for MegaPAC V-IX
2*VadEDGE 4202 (MegaPAC 2003 replacement)
6*CAB-HDR26-X21CP up to 3m
4*CAB-HDR26-V36TESTLOOP
/ 47,710.00
Installation and testing of requisite hardware, comprising:
2*days Exeter
3*days Whitehill / 4,750.00
Subtotal / 52,460.00
Optional hardware (spares), comprising:
1*MegaPAC V-IX Base System Includes a Chassis, 1 CP6000, 2 PSUs, 1 Switch
3*Baffle and Panel set to blank out 3 slots
9*Single Panel for MegaPAC V-IX
1*VadEDGE 4202 (RoHS compliant) / 23,405.00
Installation and testing for optional splitter function / 2,850.00
Subtotal / 26,255.00
TOTAL / 78,715.00
4.8The table above includes a number of optional hardware items (i.e. spares) which the group may wish to agree are necessary to ensure optimum ‘swap-out’ time in the event of a failure of the primary equipment. These units would be pre-configured by VADOS, be housed on-site at Whitehill, and allow the mean-time-to-repair to reduce from 4 hours to 30 minutes.
4.9Consideration has also been given to the installation and testing of a splitter function. The splitter function would enable the SADIS 2G comparator at Exeter to have visibility of the outbound data feed. Split feed functionality was provided for the SADIS 1G, but never implemented for SADIS 2G. At present, the SADIS 2G comparator only has visibility of the inbound (downlink) data feed – therefore not providing a true ‘comparison’. A splitter function would allow outbound data to pass to the SADIS 2G uplink chain, whilst also supplying a duplicate data feed to the SADIS 2G comparator PC.
4.10Support costs for the option 1 equipment, per annum, are provided below (correct at March 2009 prices):
Table 2–Option 1 refresh VADOS hardware and software SADIS2G support costs
OPTION 1 requisite hardware and installation (£ per annum) / OPTION 1 optional hardware (£ per annum)Hardware and software on-site support with 4-hour response. Includes telephone, software and hardware warranty. / 28,459.00 / 8,393.00
4.11Should the group decide to only install the Option 1 requisite hardware, annual support cost would be in the region of £28,459. Compare this to the present £36,918 annual charge. If the optional equipment was also purchased (to augment system availability as described below) and the splitter function installed, the support cost would be in the region of GBP 36,852 per annum (i.e. £28,459 + £8,393).
4.12Availability figures for VADOS equipment in the Option 1 configuration are shown at Figure B3 to Appendix B. They indicate thatsystem availability of VADOS hardware under Option 1 is virtually identical to the system availability of the present infrastructure – i.e. 99.993330% availability for VADOS hardware with a 4 hour MTTR, and 99.999163% for VADOS hardware with a 0.5 hour MTTR (hot swap). By purchasing the optional hardware, the group is invited to note that system availability for VADOS hardware would be the higher of these two percentages, owing to the fact that a pre-configured ‘hot swap’ unit would be available on site.
OPTION 2 – Simplified uplink topology
4.13Figure C1 of Appendix C illustrates the Option 2 topology. Changes from the existing SADIS 2G uplink infrastructure are as follows:
i)2 new VadEDGE 4200’s replace the 2 MegaPAC 2003’s at Exeter;
ii)1 new MegaPAC V-IX’s replace the 2 MegaPAC V’s at Whitehill; and
iii)Existing VadEDGE 4200 (between MegaPAC V’s and switch shown on Figure A1) would become a spare to the ISDN VadEDGE unit at Whitehill[§].
4.14In this simplified topology, two MegaPAC V’s would be replaced by just one MegaPAC V-IX unit at Whitehill. The single MegaPAC V-IX would house an additional CPU and PSU compared to the configuration shown under Option 1. By housing two CPUs within the same unit, data redundancy would be guaranteed. An internal link would be available between each CPU to provide alternate routing functionality.
4.15The Met Office has been running a near-identical service (non-SADIS) to that shown in Option 2 for a number of years without any issues, and believes that the same comments would apply to a simplified SADIS 2G topology.
4.16By using a single MegaPAC V-IX (with dual CPUs), there would be an opportunity to connect the MegaPAC V-IX directly to the switch – i.e. there would no longer be a need for the VadEDGE 4200 that currently resides between the MegaPAC V’s and the switch. This would mean that the unit would become available as a spare to the ISDN VadEDGE unit used to support SADIS data backup (and which is being procured at time of writing).
4.17The table below summarises hardware and installation costs associated with Option 2 (correct at March 2009 prices). As per the Option 1 proposal above, the Option 2 proposal includes a number of optional hardware items which the group may wish to agree are necessary to ensure optimum ‘swap-out’ time in the event of a failure of the primary equipment. Again, these units would be pre-configured by VADOS, be housed on-site at Whitehill, and allow the mean-time-to-repair to reduce from 4 hours to 30 minutes. Consideration has also been given to the installation and testing of a splitter function – as described in paragraph 4.9 above.
Table 3–Option 2 hardware refresh and installation costs (including options)
OPTION 2 / Cost (£)Requisite hardware[**], comprising:
1*MegaPAC V-IX Base System Includes a Chassis, 1 CP6000, 2 PSUs, 1 Switch
1*Additional CP6000 for use with MegaPAC V-IX
2*PSU for MegaPAC V-IX
1*8-Port WAN module for MegaPAC V-IX
3*Baffle and Panel set to blank out 3 slots
9*Single Panel for MegaPAC V-IX
2*VadEDGE 4202 (MegaPAC 2003 replacement)
6*CAB-HDR26-X21CP up to 3m
2*CAB-HDR26-V36TESTLOOP / 33,663.00
Installation and testing of requisite hardware, comprising:
2*days Exeter
3*days Whitehill / 4,750.00
Subtotal / 38,413.00
Optional hardware (spares)[††], comprising:
1*MegaPAC V-IX Base System Includes a Chassis, 1 CP6000, 2 PSUs, 1 Switch
1*8-Port WAN module for MegaPAC V-IX (RoHS Compliant)
3*Baffle and Panel set to blank out 3 slots
9*Single Panel for MegaPAC V-IX
/ 24,075.00
Installation and testing for optional splitter function / 2,850.00
Subtotal / 26,925.00
TOTAL / 65,338.00
4.18Support costs for the Option 2 equipment, per annum, are provided below (correct at March 2009 prices):
Table 4–Option 2 refresh VADOS hardware and software SADIS2G support costs
OPTION 2 requisite hardware and installation (£ per annum) / OPTION 2 optional hardware and installation(£ per annum)
Hardware and software on-site support with 4-hour response. Includes telephone, software and hardware warranty. / 22,343.00 / 9,273.00
4.19Should the group decide to only install the Option 2 requisite hardware, annual support cost would be in the region of £22,343. Again, compare this to the present £36,918 annual charge. If the optional equipment was also purchased (to augment system availability as described below) and the splitter function installed, the support cost would be in the region of£31,616 per annum (i.e. £22,343 + £9,273).
4.20Availability figures for VADOS equipment in the Option 2 configuration are shown at Figure C3 to Appendix C. They indicate that system availability of VADOS hardware under Option 2 is considerably higher than the system availability of the present infrastructure and that of Option 1. An Option 2 system would have 99.999199% availability for VADOS hardware with a 4 hour MTTR, and 99.999899% for VADOS hardware with a 0.5 hour MTTR (hot swap). Again, by purchasing the optional hardware, the group is invited to note that system availability for VADOS hardware would be the higher of these two percentages, owing to the fact that a pre-configured ‘hot swap’ unit would be available on site.
4.21Given that the SADIS 2G uplink has been simplified by Option 2, would be less expensive to install and maintain/support, and would provide higher system availability(than either the present infrastructure or Option 1), the SADIS Provider State is of the opinion that Option 2, with spares and splitter function, would be the most prudentproposal to implement.
4.22Note that if either refresh Option 1 or Option 2 was implemented before the end of 2009, the hardware and software support for 2010 (currently £36,918) would reduce close to the figures outlined at paragraphs 4.11 and 4.19 (depending on options).
5.SADIS 2G uplink protocol considerations
5.1Hardware refresh Options 1 and 2 would utilise the existing protocols to transfer data between the Met Office in Exeter to the Whitehill satellite uplink facility. Three SADIS 2G channels (X.25 PVC’s 1, 2 and 3 / TCP ports 10001, 10002 and 10003) would transmit data as X.25 over IP between Exeter and Whitehill, before converting into the VSAT protocol for transmission over the satellite link.
5.2As mentioned above, as part of a wider Met Office initiative to migrate its IT systems away from a reliance on the legacy X.25 protocol, consideration may need to be given to passing data between Exeter and Whitehill purely over IP (the ‘internet protocol’). Hardware at Whitehill could then convert the data into the VSAT protocol for promulgation over the satellite. Both option 1 and option 2 would support any elected protocol, including IP.
5.3There were, and still remain, valid reasons why X.25 over IP was chosen to be the optimum method for passing SADIS 2G data from Exeter to Whitehill. The use of X.25 over IP guarantees that the data dispatched from Exeter arrives at Whitehill without conflict or delay. Due to latency effects, it is not clear whether passing data over IP would provide such guarantees. One way, potentially, to overcome this may be to increase the bandwidth of the communications links between Exeter and Whitehill – currently dual 64K leased lines. If the linecapacity was increased, say, to 128K, latency effects may be reduced or eliminated altogether. However, it is not clear whether this may in turn lead to congestion (‘bottle-necking’) of data arriving at the point of uplink – since the satellite link is currently only configured to broadcast at 64K.
5.4Noting the Met Office desire to move away from the X.25 protocol, testing could be conducted with the support of VADOS and the SADIS Technical Development Team to determine the most efficient protocol to pass data between Exeter and Whitehill. Such testing would be conducted with no impact on the operational service.
6.Conclusions
6.1In view of the above discussion, it is clear that a hardware refresh of SADIS 2G uplink equipment is essential to ensure resilience of the service over the coming years. To do nothing could jeopardise the SADISProviderState’s ability to meet its obligations to the SADIS Agreement.
6.2Opportunities exist to overcome problems caused by the obsolescence of existing SADIS 2G uplink hub. The SADISProviderState is of the opinion that the most viable and cost effective solution would be Option 2 – a refreshed and simplified SADIS 2G uplink hub. Whilst Option 2 is simpler, it is also less expensive to install and maintain, and would benefit from higher system availability compared to the existing hub equipment and that proposed under Option 1. Whilst there would be an outlay of around £38,000 to purchase and install the Option 2 hardware (excluding spares and splitter function), ongoing support and maintenance costs would reduce by more than £14,000 per annum. If the hardware was installed before the end of 2009, these cost savings could be realised (and thus passed onto SADIS users) as early as 2010 – where the annual support and maintenance charge would reduce from £36,918 to around £22,343. Noting earlier remarks, the group may with to agree that in order to improve system availability and monitoring even further, it would be prudent to also purchase the Option 2 optional hardware (spares) and install the splitter function.