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OPNET Exercise

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Page 1: OPNET Exercise

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Page 2: OPNET Exercise

Table of contents �7DEOH�RI�FRQWHQWV ��������������������������������������������������������������������������������������������������������������������������������������� ��,QWURGXFWLRQ�DQG�SXUSRVH��������������������������������������������������������������������������������������������������������������������������� ��%HIRUH�WKH�H[HUFLVHV����������������������������������������������������������������������������������������������������������������������������������� ��'XULQJ�WKH�H[HUFLVH������������������������������������������������������������������������������������������������������������������������������������ ��,QWHUQHW�DFFHVV ������������������������������������������������������������������������������������������������������������������������������������������� ��7HOHWUDIILF�WKHRU\��������������������������������������������������������������������������������������������������������������������������������������� ��/RFDO�$UHD�1HWZRUNV��������������������������������������������������������������������������������������������������������������������������������� ��/RFDO�$UHD�1HWZRUNV�ZLWK�UHDO�WUDIILF����������������������������������������������������������������������������������������������������� ���$SSHQGL[�$�±�,QWURGXFWLRQ�WR�231(7���������������������������������������������������������������������������������������������������� ���$SSHQGL[�%�±��3HUIRUPDQFH�HYDOXDWLRQ �������������������������������������������������������������������������������������������������� �����

Page 3: OPNET Exercise

Introduction and purpose 7KH�SHUIRUPDQFH�RI�PRGHUQ�FRPPXQLFDWLRQ�QHWZRUN�LV�D�NH\�SDUDPHWHU��HVSHFLDOO\�IURP�WKH�RSHUDWRUV�SRLQW�RI�YLHZ��7KLV�LQFOXGHV�ERWK�VPDOO�QHWZRUNV�LQ�FRPSDQLHV��XS�WR�ODUJH�LQWHUQHWZRUNV�WKDW�VSDQ�WKH�HQWLUH�ZRUOG��7KH�SHUIRUPDQFH�RI�DQ�H[LVWLQJ�QHWZRUN�FDQ�EH�PHDVXUHG��EXW�WKHVH�PHDVXUHPHQWV�RQO\�UHIOHFW�WKH�FXUUHQW�VWDWH�RI�WKH�QHWZRUN���6LQFH�DSSOLFDWLRQV�DQG�XVHUV�EHKDYLRXU�FKDQJH�RYHU�WLPH��WKH�QHWZRUN�RSHUDWRU�PXVW�FRQVWDQWO\�PRGLI\�DQG�LPSURYH�RQ�WKH�QHWZRUN��+RZHYHU��FKDQJLQJ�D�QHWZRUN�WR�PHHW�QHZ�JRDOV�LV�QRW�HDV\�LI�LW�KDV�WR�EH�GRQH�UDWLRQDOO\��HVSHFLDOO\�IURP�DQ�HFRQRPLFDO�SRLQW�RI�YLHZ���7KHUHIRUH��WKH�QHWZRUN�RSHUDWRU�PXVW�EH�DEOH�WR�DQDO\VH��ZKDW�LI��VFHQDULRV��L�H���ZKDW�ZLOO�EH�WKH�HIIHFW�RQ�WKH�SHUIRUPDQFH�RI�WKH�QHWZRUN�LI�DQRWKHU�URXWHU�LV�LQVWDOOHG��RU�LI�RQH�RI�WKH�OLQNV�LV�XSJUDGHG�WR�D�KLJKHU� ELW� UDWH�� 8QIRUWXQDWHO\�� DOO� EXW� WKH� VLPSOHVW� QHWZRUNV� DUH� WRR� FRPSOH[� WR� DQDO\VH� IURP� D�WKHRUHWLFDO�SRLQW�RI�YLHZ��XVLQJ�PDWKHPDWLFDO�PHWKRGV��7KH�QHWZRUN�RSHUDWRU�PXVW� WKHUHIRUH� WXUQ�KLV�DWWHQWLRQ�HOVHZKHUH��2QH�VROXWLRQ�LV�WR�XVH�VLPXODWLRQ��+HUH��VLPXODWLRQ�FDQ�EDVLFDOO\�EH�GHVFULEHG�DV�EXLOGLQJ�D�PRGHO�RI�WKH�QHWZRUN�XQGHU�FRQVLGHUDWLRQ�LQVLGH�D�FRPSXWHU��DQG�LQWURGXFH�WUDIILF�LQWR�WKLV�PRGHO��7KH�FRPSXWHU�FDQ�WKHQ�VLPXODWH�WKH�QHWZRUN��DQG�SURYLGH�VRPH�VWDWLVWLFDO�SDUDPHWHUV�DV�RXWSXW�RI� WKH�VLPXODWLRQ��7KH�QHWZRUN�RSHUDWRU�FDQ�XVH� WKHVH� UHVXOWV�DV�EDVLV� IRU�GHWHUPLQLQJ��ZKDW�PXVW�EH�GRQH�WR�FKDQJH�WKH�QHWZRUN����,Q�WKLV�H[HUFLVH��\RX�ZLOO�EH�DEOH�WR�XVH�D�SURIHVVLRQDO�VLPXODWLRQ�WRRO��231(7��WR�DQDO\VH�D�QXPEHU�RI�QHWZRUNLQJ�VFHQDULRV��7KH�SXUSRVH�RI�WKLV�H[HUFLVH�LV��

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Page 4: OPNET Exercise

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Page 5: OPNET Exercise

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Page 6: OPNET Exercise

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Page 9: OPNET Exercise

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Page 10: OPNET Exercise

7DVN�� )RU� WKH�+XE� EDVHG� QHWZRUN�� GHWHUPLQH� WKH� HIIHFW� RQ� WKH� HQG�WR�HQG� GHOD\� DQG� WKURXJKSXW� IRU�YDOXHV� RI� WKH� VWDWLRQ¶V� WUDQVPLVVLRQ� UDWH� LQ� WKH� UDQJH� ���� NELW�V� WR� ���� NELW�V�� &DQ� \RX� GHVFULEH� WKH�HIIHFW"�1RZ�SHUIRUP�WKH�VDPH�VLPXODWLRQ�IRU�WKH�VZLWFK�EDVHG�(WKHUQHW��DQG�FRPSDUH�WKH�UHVXOWV�ZLWK�WKH�KXE�EDVHG�(WKHUQHW���One aspect of the MAC algorithm used in wireless LANs is the optional RTS/CTS mechanism. In the next task, the effect of this mechanism is studied. The advantage of this mechanism is most clear in wireless LANs with a low (physical) bit rate. In WLANs with higher bit rates (e.g., 11 Mbit/s) the RTS/CTS mechanism is not useful. In the following task, the focus will therefore be on a low bit rate WLAN. Task: Based on the wireless scenario, make a duplicate scenario. Change the type of stations from 11 Mbit/s Direct Sequence to 1 Mbit/s Frequency hopping. Create duplicate scenarios1 of this, so that you have 4 different scenarios with the following properties:

• Packet size = 2300 bytes, bitrate = 10 kbit/s, RTS/CTS not used • Packet size = 2300 bytes, bitrate = 10 kbit/s, RTS/CTS used • Packet size = 2300 bytes, bitrate = 70 kbit/s, RTS/CTS not used • Packet size = 2300 bytes, bitrate = 70 kbit/s, RTS/CTS used.

Plot the end-to-end delay and throughput in overlaid mode for the two 10 kbit/s scenarios and the two 70 kbit/s scenarios. Comment on the graphs.

Local Area Networks with real traffic The last group of simulations to be performed in this exercise are intended to illustrate the performance of 4 different types of Ethernet LANs, each with 15 workstations and 1 server, in the case of real types of traffic; file transfers and web browsing. The considered networks are:

• 10 Mbit/s hub based • 10 Mbit/s switch based • 10 Mbit/s switch based, but with 100 Mbit/s connection to a server • 100 Mbit/s switch based

Open the project IntroLans2. No networks have been created yet in this project, but there will be two objects, an ApplicationConfig and a ProfileConfig object. These are standard OPNET objects that are used to define traditional applications and user profiles. In this project, the ApplicationConfig object defines that the network will carry FTP and HTTP traffic, and the ProfileConfig object defines a user profile that uses both of these applications. To quickly construct a network, use the Topology=>Rapid Configuration menu. In the dialog box, create a star network with an ethernet16_hub as the center node, 16 ethernet_wkstn as periphery nodes and 10Base-T as the link model.

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Page 11: OPNET Exercise

First, select one of the workstations and change the model attribute to ethernet_server and indicate that it should support all applications (Application: Supported Services = All). Second, change all remaining 15 workstations so that the Application: Supported Profiles indicate the Standard User profile is to be used (You will have to change rows to 1) Third, indicate that OPNET should collect the HTTP.Page Response Time and the FTP.Download Response Time statistics. The first of the network of interest is now created. To create the remaining three networks, first make a duplicate scenario, and change the model of the central device to ethernet16_switch. Now create two duplicate scenarios of this and change the link model to 100BaseT for only the switch ↔ server link in the first duplicate and for all the links in the second duplicate. Task: Now, all four networks under interest have been created, and you can start the simulations. Create graphs of the HTTP page response time and the FTP download response time and comment on these.

Page 12: OPNET Exercise

Appendix A – Introduction to OPNET 7KH�SXUSRVH�RI�WKLV�DSSHQGL[�LV�WR�JLYH�D�EULHI�LQWURGXFWLRQ�WR�WKH�VLPXODWLRQ�WRRO�³231(7�0RGHOHU����´���

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The Network Domain ,Q�WKH�1HWZRUN�'RPDLQ��WKH�WDUJHW�QHWZRUN�LV�UHSUHVHQWHG�E\�D�QXPEHU�RI�LFRQV��0RVW�RI�WKH�LFRQV�UHSUHVHQW�VRPH�IRUP�RI�QHWZRUNLQJ�HTXLSPHQW��H�J���D�ZRUNVWDWLRQ��D�URXWHU��RU�RWKHU��)LJXUH���VKRZV�D�VLPSOH�QHWZRUN�FRQVLVWLQJ�RI�D�ZHE�VHUYHU��DQ� DFFHVV�URXWHU�� WKH� ,QWHUQHW�� DQG� ,63� DQG� ILQDOO\� D� XVHU��7KHUH� DUH� WZR� RWKHU� LFRQV� LQ� ILJXUH� ��� ZKLFK� UHSUHVHQW� WKH�DSSOLFDWLRQV� DQG� WKH� XVHU� SURILOHV� WKDW� DUH� XVHG� RQ� WKLV�QHWZRUN����<RX�ZLOO�QRWH�D�UHFWDQJOH�DURXQG�WKH�,63�DQG�WKH�8VHU��7KLV�LQGLFDWHV�WKDW�WKH�LFRQV�DUH�QRW�D�VLPSOH�GHYLFH��EXW�LQVWHDG�D�VXEQHW� LQ� 231(7� WHUPV�� 6XEQHWV� DUH� XVHG� LQ� 231(7� WR�LPSRVH� VRPH� IRUP� RI� KLHUDUFK\� LQ� WKH� QHWZRUN� GRPDLQ��2WKHUZLVH�� LI� D� VLPXODWLRQ� RQ� D� QHWZRUN� ZLWK� PRUH� WKDQ�PRUH�������FRPSXWHUV�DQG�RWKHU�GHYLFHV�LV�WR�EH�SHUIRUPHG��DQG� HDFK� GHYLFH� ZDV� UHSUHVHQWHG� E\� DQ� LFRQ�� WKH� PDLQ�ZLQGRZ� ZRXOG� FRQWDLQ� VR� PDQ\� LFRQV�� WKDW� LW� ZRXOG� EH�DOPRVW�LPSRVVLEOH�WR�ZRUN�ZLWK��8VLQJ�VXEQHWV��LW�LV�SRVVLEOH�WR�UHSUHVHQW��H�J���WKH�FRPSXWHUV�LQ�D�GHSDUWPHQW�DV�D�VXEQHW��'RXEOH�FOLFNLQJ�RQ�D�VXEQHW�RSHQV�RS�WKH�VXEQHW�IRU�YLHZLQJ�HGLWLQJ��5HWXUQLQJ�WR�D�KLJKHU�OHYHO�LQ�WKH�KLHUDUFK\�LV�GRQH�E\�ULJKW�FOLFNLQJ�RQ�WKH�EDFNJURXQG�DQG�VHOHFWLQJ�Go To Parent Subnet�RU�VLPSO\�SUHVVLQJ�WKH� �EXWWRQ�����7KH�LFRQV�LQ�WKH�PDLQ�ZLQGRZ��DQG�VXEQHW�YLHZV��DUH�WKH�³EXLOGLQJ�EORFNV´�IRU�WKH�VLPXODWLRQV��,Q�PDQ\�FDVHV��WKH�VLPXODWLRQ�FDQ�XVH�WKH�EXLOGLQJ�EORFNV�SURYLGHG�ZLWK�231(7��+RZHYHU��D�PRUH�GHWDLOHG�DQDO\VLV�ZLOO�UHTXLUH�WKDW�FXVWRP�EXLOGLQJ�EORFNV�ZLOO�EH�FUHDWHG���

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Page 13: OPNET Exercise

The Node Domain ,Q� WKH� 1RGH� 'RPDLQ�� WKH� ³LQQHU´� ZRUNLQJ� RI� WKH� EORFNV� LQ� WKH�1HWZRUN�GRPDLQ�LV�VSHFLILHG��6HH�ILJXUH����7KH�EORFNV�LQ�WKH�QRGH�GRPDLQ� UHSUHVHQW� WKH� EDVLF� IXQFWLRQV� RI� D� QRGH� LQ� WKH� QHWZRUN��(DFK� EORFN� FRQWDLQV� VRPH� RI� WKH� WRWDO� IXQFWLRQDOLW\�� 7KH� UHDGHU�PLJKW� QRWH� D� VLPLODULW\� EHWZHHQ� ILJXUH� �� �ZKLFK� GHSLFWV� D�ZRUNVWDWLRQ��DQG�ILJXUH�+�����LQ�WKH�WH[WERRN���0DQ\� RI� WKHVH� QRGHV� LQ� WKH� QRGH� YLHZ� DUH� VWDQGDUG� 231(7�EORFNV��EXW� LW� LV�DOVR�SRVVLEOH� WR�FUHDWHG�QHZ�QRGHV��7KH�IXQFWLRQ�RI�VXFK�D�FXVWRP�QRGH�LV�VSHFLILHG�LQ�WKH�SURFHVV�GRPDLQ��

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Page 15: OPNET Exercise

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Page 17: OPNET Exercise

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Page 18: OPNET Exercise

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Viewing the results :KHQ� WKH� VLPXODWLRQV� KDYH� EHHQ� SHUIRUPHG�� \RX� FDQ� YLHZ� WKH� UHVXOWV� E\� VHOHFWLQJ� Results->View Results (Advanced)�IURP�WKH�SURMHFW�ZLQGRZ��)LUVW�VWHS�LV�WR�ORDG�WKH�RXWSXW�VFDODU�ILOH��File->Load Output Scalar File...��DQG�VHOHFW�\RXU�ILOH���<RX�FDQ�QRZ�YLHZ�WZR�W\SHV�RI�JUDSKV��F�I���WKH�IROORZLQJ�ILJXUH��:LWK�WKH�PLGGOH�EXWWRQ��\RX�FDQ�FUHDWH�D�JUDSK�ZLWK�RQH�FXUYH�DQG�ZLWK�WKH�ULJKW�EXWWRQ�\RX�FDQ�FUHDWH�VHULHV�RI�FXUYHV�LQ�WKH�VDPH�JUDSK��7KH�ILUVW�W\SH�RI� JUDSKV� FDQ� EH� XVHG�� LI� \RX�ZLVK� WR� GLVSOD\� RQH� GHSHQGHQW� YDULDEOH� DV� D�IXQFWLRQ�RI� RQH� LQGHSHQGHQW� YDULDEOH��7KH� VHFRQG� W\SH�RI� JUDSKV� LV� XVHG� WR�GLVSOD\�D�GHSHQGHQW�YDULDEOH�DV�D�IXQFWLRQ�RI�WZR�LQGHSHQGHQW�YDULDEOHV��

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Page 19: OPNET Exercise

Appendix B – Performance evaluation :KHQ�ZDQWLQJ� WR� HYDOXDWH� WKH� SHUIRUPDQFH� RI� D� JLYHQ� V\VWHP� �WKLV� FRXOG� EH� DQ\� V\VWHP�� WKHUH� DUH�FRQFHSWXDOO\�WKUHH�PHWKRGV��DQDO\WLFDO�PRGHOV��PHDVXUHPHQWV�DQG�VLPXODWLRQ����$QDO\WLFDO�PRGHOV�DUH�H[DFW�PDWKHPDWLFDO�UHSUHVHQWDWLRQV�RI�WKH�V\VWHPV��'HSHQGLQJ�RQ�WKH�W\SH�RI�WKH�V\VWHP� GLIIHUHQW� DUHDV� RI� PDWKHPDWLFV� FRPH� LQWR� SOD\�� :KHQ� VSHDNLQJ� PRGHOV� RI� FRPPXQLFDWLRQ�QHWZRUN� LW� LV� WKH� DUHDV� RI� JUDSK� WKHRU\� DQG� TXHXLQJ� WKHRU\�� +RZHYHU�� WKRVH� PRGHOV� RIWHQ� JHW� WRR�FRPSOLFDWHG�DQG�LW�PLJKW�EH�WKDW�HYHQ�LI�WKH\�KDYH�D�VROXWLRQ�WKHQ�LW�LV�IDU�WRR�FXPEHUVRPH�WR�ILQG�LW����0HDVXUHPHQWV� DUH� JHQHUDOO\� JRRG� EHFDXVH� WKH\� JLYH� UHVXOWV� WKDW� UHIOHFW� WKH� UHDO�ZRUOG��7KH� SUREOHP�KHUH�LV�ILUVW�RI�DOO�WR�JHW�DFFHVV�WR�WKH�HTXLSPHQW��,I�LW�LV�D�QHZO\�GHYHORSHG�V\VWHP�RU�D�FRPSOHWHO\�QHZ�FRQFHSW� RU� WHFKQRORJ\� LW�PLJKW� EH�GLIILFXOW� WR� ILQG� DQ\� HTXLSPHQW�RU� LW�PLJKW� QRW� H[LVW�� )XUWKHUPRUH�H[SHULPHQWDO�VHWXSV�PLJKW�VLPSO\�QRW�EH�SRVVLEOH�IRU�YHU\�ODUJH�QHWZRUNV��IRU�HFRQRPLFDO�UHDVRQV����6LPXODWLRQ� LV� SHUIRUPHG� E\� EXLOGLQJ� D� PRGHO�� ,Q� WKLV� PRGHO� FKDQJHV� LQ� WKH� VWDWH� RI� D� V\VWHP� DUH�REVHUYHG� DV� D� IXQFWLRQ� RI� WLPH�� %RWK� FRQWLQXRXV� DQG� GLVFUHWH� PRGHOV� DUH� SRVVLEOH�� ,I� WKHUH� DUH� DQ�XQFRXQWDEOH��LQILQLWH�QXPEHU�RI�VWDWHV�LQ�WKH�V\VWHP�LW�LV�VDLG�WR�EH�FRQWLQXRXV�VWDWH��,I�RQO\�D�GLVFUHWH�QXPEHU�RI�VWDWHV�DUH�SRVVLEOH�LW�LV�D�GLVFUHWH�VWDWH�PRGHO��'LVFUHWH�VWDWH�PRGHOV�DUH�DOVR�FDOOHG�GLVFUHWH�HYHQW�PRGHOV��$Q�HYHQW�LQ�WKLV�FRQWH[W�LV�GHILQHG�DV�D�FKDQJH�LQ�WKH�VWDWH�RI�WKH�V\VWHP��/LNHZLVH�LQ�WKH�ZD\�WLPH�LV�SHUFHLYHG�WKHUH�DUH�WZR�GLVWLQFW�SRVVLELOLWLHV��FRQWLQXRXV�DQG�GLVFUHWH���

Event driven simulation $� VLPXODWLRQ� XVLQJ� D� GLVFUHWH� VWDWH� PRGHO� LV� FDOOHG� D� GLVFUHWH� HYHQW� VLPXODWLRQ�� 'LVFUHWH� HYHQW�VLPXODWLRQ�FRPHV�LQ�WZR�IODYRXUV��XQLW�WLPH�DQG�HYHQW�GULYHQ��,Q�XQLW�GULYHQ�VLPXODWLRQ�WLPH�DGYDQFHV�RQH�XQLW� DW� D� WLPH� �KHQFH� WKH� QDPH�� DQG� LI� DQ� HYHQW� LV� VFKHGXOHG� DW� WKDW� WLPH� SURSHU� DFWLRQ� LV� WDNHQ�RWKHUZLVH�QRWKLQJ�LV�GRQH��2IWHQ��KRZHYHU��WKHUH�LV�QR�QHHG�WR�OHW�WLPH�DGYDQFH�LQ�VWHSV�RI�RQH�XQLW�DW�D�WLPH��:K\�QRW�MXVW�VNLS�DOO�WKH�SHULRGV�ZKHUH�WKHUH�LV�QR�DFWLRQ�WR�EH�WDNHQ�DQ\ZD\"�7KLV�LV�WKH�LGHD�RI�HYHQW�GULYHQ�VLPXODWLRQ��$FWLRQV�DUH�WULJJHUHG�E\�HYHQWV�WKDW�KDSSHQ�DW�D�FHUWDLQ�WLPH��7KH�V\VWHP�WLPH�LV�DGYDQFHG�WR�WKH�SRLQW�RI�WLPH�ZKHUH�WKH�QH[W�HYHQW�LV�VFKHGXOHG���,W� WXUQV� RXW� WKDW� HYHQW� GULYHQ� VLPXODWLRQ� LV� SDUWLFXODUO\� XVHIXO� IRU� VLPXODWLRQ� RI� SDFNHW� EDVHG�FRPPXQLFDWLRQ� V\VWHPV�� +HUH�� RQH� LV� XVXDOO\� LQWHUHVWHG� LQ� NQRZLQJ� ZKDW� KDSSHQV� ZKHQ� D� SDFNHW�DUULYHV�DW�D�TXHXLQJ�SRLQW��H�J��VZLWFK�RU�URXWHU���ZKHQ�GRHV�LW�OHDYH�WKH�TXHXH�DQG�ZKDW�KDSSHQV�WKHQ"�,�H��D�W\SLFDO�HYHQW�FRXOG�EH�WKDW�D�SDFNHW�S�DUULYHV�DW�TXHXH�T�DW�WLPH�W���7KHUH�DUH�GUDZEDFNV��WRR��7KLV�W\SH�RI� VLPXODWLRQ� LV� QRW�ZHOO� VXLWHG� IRU� VLPXODWLRQ�RI� KRZ� WKH�ELWV� SURSDJDWH�RQ� WKH� DFWXDO� SK\VLFDO�PHGLXP��IRU�LQVWDQFH����

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Page 20: OPNET Exercise

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Initialize all modelelements

Pick next eventfrom priority

queue

Pass control tocorrespondingevent handler

Advance time

End ofsimulation

Stop

Statistics

YES

NO

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