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[์ž๋ฃŒ๊ตฌ์กฐ] 13. ํƒ์ƒ‰ ํƒ์ƒ‰์ด๋ž€? ํƒ์ƒ‰ํ‚ค: ํ•ญ๋ชฉ๊ณผ ํ•ญ๋ชฉ์„ ๊ตฌ๋ณ„ํ•ด์ฃผ๋Š” ํ‚ค ์ •๋ ฌ๋˜์ง€ ์•Š์€ ๋ฐฐ์—ด์—์„œ์˜ ํƒ์ƒ‰ ์ˆœ์ฐจํƒ์ƒ‰(sequential search) : ์ •๋ ฌ๋˜์ง€ ์•Š์€ sequence์—์„œ ์ฒ˜์Œ๋ถ€ํ„ฐ ๋งˆ์ง€๋ง‰๊นŒ์ง€ ์ˆœ์ฐจ์ ์œผ๋กœ ํ•˜๋‚˜์”ฉ ๊ฒ€์‚ฌํ•˜๋Š” ๋ฐฉ๋ฒ• --> O(n) ์ •๋ ฌ๋œ ๋ฐฐ์—ด์—์„œ์˜ ํƒ์ƒ‰ ์ด์ง„ํƒ์ƒ‰(binary search) : ์ •๋ ฌ๋œ ๋ฐฐ์—ด์˜ ์ค‘์•™์— ์žˆ๋Š” ๊ฐ’์„ ์กฐ์‚ฌํ•˜์—ฌ, ์ฐพ๊ณ ์ž ํ•˜๋Š” ํ•ญ๋ชฉ์ด ๊ทธ ๊ฐ’๋ณด๋‹ค ์ž‘์€์ง€ ํฐ์ง€ ํŒ๋‹จํ•˜์—ฌ, ํƒ์ƒ‰์˜ ๋ฒ”์œ„๋ฅผ ๋ฐ˜์œผ๋กœ ์ค„์—ฌ๊ฐ€๋ฉฐ ํƒ์ƒ‰ํ•œ๋‹ค. --> O(log(n)) ์ƒ‰์ธ ์ˆœ์ฐจํƒ์ƒ‰(indexed sequential search) : ์ธ๋ฑ์Šค ํ…Œ์ด๋ธ”์„ ๋จผ์ € ๊ฒ€์‚ฌํ•˜์—ฌ, ํƒ์ƒ‰ํ‚ค๊ฐ€ ์†ํ•œ ๋ฒ”์œ„๋ฅผ ์•Œ์•„๋‚ธ ํ›„, ์ˆœ์ฐจํƒ์ƒ‰ํ•œ๋‹ค. ๋ณด๊ฐ„ํƒ์ƒ‰(interpolation search) : ๋ฐฐ์—ด[0]๊ณผ ๋ฐฐ์—ด[n-1] ๊ฐ’์„ ํ†ตํ•ด ํƒ์ƒ‰ํ‚ค๊ฐ€ ์กด์žฌํ•  ์œ„์น˜๋ฅผ .. 2023. 12. 14.
[์ž๋ฃŒ๊ตฌ์กฐ] 12. ์ •๋ ฌ ์„ ํƒ์ •๋ ฌ(selection sort) : ์ •๋ ฌ๋˜์ง€ ์•Š์€ ๊ณณ์—์„œ ๋น„๊ตํ•˜์—ฌ, ๊ฐ€์žฅ ์ž‘์€ ์• ์™€ ๋ฐฐ์—ด์˜ ๋งจ ์•ž์˜ ์• ๋ฅผ ๊ตํ™˜ํ•œ๋‹ค. - ์‹œ๊ฐ„๋ณต์žก๋„: O(n^2) - unstable sort - in-place sort ๋น„๊ต์—ฐ์‚ฐ: ์ •๋ ฌ๋˜์ง€ ์•Š์€ ๊ณณ์—์„œ ์ œ์ผ ์ž‘์€ ์•  ์ด๋™์—ฐ์‚ฐ: ๊ตํ™˜ --> unstable sort ์‚ฝ์ž…์ •๋ ฌ(insertion sort) : ์ •๋ ฌ๋˜์ง€ ์•Š์€ ๊ณณ์˜ ๋งจ ์•ž์˜ ์• ๋ฅผ, ์ •๋ ฌ๋œ ๊ณณ์—์„œ ๋น„๊ตํ•˜์—ฌ ์ ์ ˆํ•œ ์ž๋ฆฌ์— ์‚ฝ์ž…ํ•œ๋‹ค. - ์‹œ๊ฐ„๋ณต์žก๋„: ์ตœ์•…์˜ ๊ฒฝ์šฐ๋Š” O(n^2), ์ตœ์„ ์˜ ๊ฒฝ์šฐ๋Š” O(n); ๋Œ€๋ถ€๋ถ„ ์ •๋ ฌ๋˜์–ด ์žˆ์œผ๋ฉด ๋งค์šฐ ํšจ๊ณผ์ ์ด๋‹ค. - stable sort - in-place sort key๊ฐ’์— ์ •๋ ฌ๋˜์ง€ ์•Š์€ ๋ถ€๋ถ„์˜ ๋งจ ์•ž์˜ ์• ๋ฅผ ๋„ฃ๋Š”๋‹ค. --> ๊ณต๊ฐ„๋ณต์žก๋„: O(1): in-place sort ๋น„๊ต์—ฐ์‚ฐ:.. 2023. 12. 14.
[์ž๋ฃŒ๊ตฌ์กฐ] 11. ๊ทธ๋ž˜ํ”„(2) ์ตœ์†Œ๋น„์šฉ ์‹ ์žฅํŠธ๋ฆฌ(MST: Minimum Spanning Tree) ์‹ ์žฅํŠธ๋ฆฌ(spanning tree): ๊ทธ๋ž˜ํ”„ ๋‚ด์˜ ๋ชจ๋“  ์ •์ ์„ ํฌํ•จํ•˜๋Š” ํŠธ๋ฆฌ (์‚ฌ์ดํด x) ์ตœ์†Œ๋น„์šฉ ์‹ ์žฅํŠธ๋ฆฌ(MST): ๋ชจ๋“  ์ •์ ๋“ค์„ ๊ฐ€์žฅ ์ž‘์€ ๋น„์šฉ์œผ๋กœ ์—ฐ๊ฒฐํ•˜๋Š” ํŠธ๋ฆฌ Kruscal์˜ MST ์•Œ๊ณ ๋ฆฌ์ฆ˜ : ๋ชจ๋“  edge๋ฅผ ๊ฒ€์‚ฌํ•˜์—ฌ, least-weight edge๋ฅผ ์ฐพ๊ณ , ๊ทธ edge๊ฐ€ ์‚ฌ์ดํด์„ ๋งŒ๋“ค์ง€ ์•Š์œผ๋ฉด, ์ถ”๊ฐ€ํ•œ๋‹ค. => ์‹œ๊ฐ„๋ณต์žก๋„: O(e*log(e)), ๋ชจ๋“  edge๋“ค์˜ weight๋ฅผ ํ•œ๋ฒˆ์— ๋น„๊ตํ•˜๋ฏ€๋กœ, ํฌ๋ฐ•ํ•œ ๊ทธ๋ž˜ํ”„์—์„œ ์œ ๋ฆฌํ•˜๋‹ค. Union-Find ์•Œ๊ณ ๋ฆฌ์ฆ˜: ์‚ฌ์ดํด์„ ๋งŒ๋“œ๋Š”์ง€ ๊ฒ€์‚ฌํ•˜๋Š” ์•Œ๊ณ ๋ฆฌ์ฆ˜ Find: ์–ด๋–ค ๋‘ ๋…ธ๋“œ์˜ root๋ฅผ ์ฐพ์•„๋‚ธ๋‹ค. root๊ฐ€ ์„œ๋กœ ๋‹ค๋ฅด๋‹ค๋ฉด, ๋‘ ๋…ธ๋“œ ์‚ฌ์ด์˜ edge๋Š” bridge์ด๋ฏ€๋กœ, ๊ทธ edge๋Š”.. 2023. 12. 14.
[์ž๋ฃŒ๊ตฌ์กฐ] 10. ๊ทธ๋ž˜ํ”„(1) ๊ทธ๋ž˜ํ”„ ๊ทธ๋ž˜ํ”„ ์šฉ์–ด ๊ทธ๋ž˜ํ”„ ์ •์˜ ๋ฌด๋ฐฉํ–ฅ ๊ทธ๋ž˜ํ”„, ๋ฐฉํ–ฅ ๊ทธ๋ž˜ํ”„ ๊ฐ€์ค‘์น˜ ๊ทธ๋ž˜ํ”„ ๋ถ€๋ถ„ ๊ทธ๋ž˜ํ”„ ๊ทธ๋ž˜ํ”„ ์šฉ์–ด ์ธ์ ‘ ์ •์  ์ •์ ์˜ ์ฐจ์ˆ˜ ์ง„์ž… ์ฐจ์ˆ˜(in-degree) ์ง„์ถœ ์ฐจ์ˆ˜(out-degree) ๊ฒฝ๋กœ(path) ๋‹จ์ˆœ ๊ฒฝ๋กœ(simple cycle): ๋ฐ˜๋ณต๋˜๋Š” ์ •์  ์—†์Œ ์‚ฌ์ดํด(cycle): ์‹œ์ž‘ ์ •์  = ์ข…๋ฃŒ ์ •์  ๋‹จ์ˆœ ์‚ฌ์ดํด(simple cycle) ์˜ค์ผ๋Ÿฌ ์‚ฌ์ดํด: ๋ชจ๋“  edge ํ•œ๋ฒˆ์”ฉ๋งŒ ๊ฑฐ์ณ์„œ ์ œ์ž๋ฆฌ๋กœ์œผ๋กœ ๋Œ์•„์˜จ๋‹ค. (๋‹จ์ˆœ ์‚ฌ์ดํด x) ํ—ค๋ฐ€ํ„ด ์‚ฌ์ดํด: ๋ชจ๋“  node ํ•œ๋ฒˆ์”ฉ๋งŒ ๊ฑฐ์ณ์„œ ์ œ์ž๋ฆฌ๋กœ ๋Œ์•„์˜จ๋‹ค. (๋‹จ์ˆœ ์‚ฌ์ดํด) ๊ทธ๋ž˜ํ”„ ์—ฐ๊ฒฐ ์ •๋„ ์—ฐ๊ฒฐ ๊ทธ๋ž˜ํ”„ ๋น„์—ฐ๊ฒฐ ๊ทธ๋ž˜ํ”„ ์™„์ „ ๊ทธ๋ž˜ํ”„: ๋ชจ๋“  ์ •์ ์ด ์—ฐ๊ฒฐ๋˜์–ด ์žˆ๋Š” ๊ทธ๋ž˜ํ”„ ๊ทธ๋ž˜ํ”„์˜ ํ‘œํ˜„ ๋ฐฉ๋ฒ• ์ธ์ ‘ ํ–‰๋ ฌ(adjacent matrix) ์ธ์ ‘ ๋ฆฌ์ŠคํŠธ(adjacent list) ๊ทธ๋ž˜.. 2023. 12. 14.
[๋„คํŠธ์›Œํฌ] 5.7 ๋„คํŠธ์›Œํฌ ๊ด€๋ฆฌ์™€ SNMP, NETCONF/YANG ๋„คํŠธ์›Œํฌ ๊ด€๋ฆฌ SNMP NETCONF YANG Network management๋Š” ์‚ฌ์‹ค ๋‹ค์†Œ ๋ณต์žกํ•œ ๋‚ด์šฉ์ด๋‹ค. ์šฐ๋ฆฌ๋Š” ๋Œ€๋žต์ ์ธ ๊ฐœ๋…๋งŒ ๋ฐฐ์šด๋‹ค! What is network management? Components for network management Managing server: ๋„คํŠธ์›Œํฌ ์ „์ฒด๋ฅผ ์ปจํŠธ๋กคํ•˜๋Š” ์„œ๋ฒ„ Managed device: managing server์— ์˜ํ•ด manage๋˜๋Š” ์žฅ์น˜๋“ค (server, client, router, switch๋ฅผ ํฌํ•จํ•œ๋‹ค.) Data: managed device ๋‚ด์˜ ๋ฐ์ดํ„ฐ (= MIB) Network management protocol: managing server๊ฐ€ managed device๋ฅผ ๊ด€๋ฆฌํ•˜๊ธฐ ์œ„ํ•œ ํ”„๋กœํ† ์ฝœ (์˜ˆ: SNMP) Network ope.. 2023. 12. 10.
[๋„คํŠธ์›Œํฌ] 5.6 ์ธํ„ฐ๋„ท ์ œ์–ด ๋ฉ”์‹œ์ง€ ํ”„๋กœํ† ์ฝœ(ICMP) ์ด์ œ SDN์— ๋Œ€ํ•œ ์ด์•ผ๊ธฐ๋ฅผ ๋งˆ์ณค๋‹ค. Network management์— ๋Œ€ํ•ด ์ด์•ผ๊ธฐํ•ด๋ณด์ž. Network management: ๋„คํŠธ์›Œํฌ๋ฅผ ๋ชจ๋‹ˆํ„ฐ๋งํ•˜๊ณ  ์žˆ๋‹ค๊ฐ€, ๋„คํŠธ์›Œํฌ์— ๋ฌธ์ œ๊ฐ€ ์ƒ๊ธฐ๋ฉด, ์ด๋ฅผ ํ•ด๊ฒฐํ•˜๋Š” ๊ฒƒ! ICMP: Internet Control Message Protocol โ–ท host์™€ router๊ฐ€ ๋„คํŠธ์›Œํฌ ์ƒํƒœ์ •๋ณด๋ฅผ ๊ตํ™˜ํ•˜๋Š” ๋ฐ์— ์‚ฌ์šฉ๋œ๋‹ค. Error reporting: router์—์„œ destination host๋กœ ๋ฐ์ดํ„ฐ๋ฅผ ์ „์†กํ•˜๋‹ค๊ฐ€ ๋ฌธ์ œ๊ฐ€ ์ƒ๊ฒผ์„ ๋•Œ, ์ด๋ฅผ source host์—๊ฒŒ ์•Œ๋ฆฐ๋‹ค. ping - ping ๋ณด๋‚ผ ๋•Œ: echo request - ping ๋ฐ›์„ ๋•Œ: echo reply --> echo reply๊ฐ€ ์˜ค๋ฉด, ๊ทธ host๊ฐ€ running ์ƒํƒœ์ž„์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. TTL expir.. 2023. 12. 10.
[๋„คํŠธ์›Œํฌ] 5.5 SDN control plane SDN (Software Defined Networking) ์ง€๊ธˆ๊นŒ์ง€ traditional routing์— ๋Œ€ํ•ด ๋ฐฐ์› ๋‹ค. ์ด์ œ SDN์— ๋Œ€ํ•ด ์•Œ์•„๋ณด์ž. Traditional Internet: Per-router Control Plane Traditional routing์˜ problem: "monolitic" router (ํ•˜๋“œ์›จ์–ด๋ถ€ํ„ฐ ์–ดํ”Œ๋ฆฌ์ผ€์ด์…˜๊นŒ์ง€ ํ•˜๋‚˜๋กœ ๋ฌถ์—ฌ ์žˆ๋‹ค.) Solution: "middlebox" Traffic Engineering: Difficult with Traditional Routing Traffic engineering: traffic์ด ๊ฑฐ์ณ๊ฐ€๋Š” ๊ธธ์„ ์กฐ์ •ํ•˜๋Š” ๊ฒƒ --> Traditional routing์—์„œ๋Š” traffic engineering์ด ์–ด๋ ต๋‹ค. --> SDN: Gen.. 2023. 12. 10.
[๋„คํŠธ์›Œํฌ] 5.4 ์ธํ„ฐ๋„ท ์„œ๋น„์Šค ์ œ๊ณต์—…์ž(ISP) ๊ฐ„์˜ ๋ผ์šฐํŒ…: BGP Routing protocols in the Internet: Popular unicast routing protocols Interior (Intra-AS routing) RIP OSPF Exterior (Inter-AS routing) BGP 5.4 ์ธํ„ฐ๋„ท ์„œ๋น„์Šค ์ œ๊ณต์—…์ž(ISP) ๊ฐ„์˜ ๋ผ์šฐํŒ…: BGP: ์„œ๋กœ ๋‹ค๋ฅธ AS ๊ฐ„์˜ routing Inter-AS Routing: A Role In Intradomain ForwardingAS1์—์„œ AS1 ๋ฐ–์˜ router 3b๋กœ datagram์„ ๋ณด๋‚ด๊ณ  ์‹ถ์–ด ํ•˜๋Š” ์ƒํ™ฉ์„ ์ƒ์ƒํ•ด๋ณด์ž. ์ด๋•Œ AS1์ด ์•Œ์•„์•ผ ํ•  ์ •๋ณด๋Š” ๋‘ ๊ฐ€์ง€๋‹ค.3b๋กœ ๊ฐ€๊ธฐ ์œ„ํ•ด์„œ๋Š” ์–ด๋–ค AS๋กœ ์ด๋™ํ•ด์•ผ ํ•˜๋Š”๊ฐ€?AS3์œผ๋กœ ์ด๋™ํ•ด์•ผ ํ•จ์„ ์•Œ์•˜๋‹ค. AS3์œผ๋กœ ๊ฐ€๊ธฐ ์œ„ํ•ด์„œ๋Š” ๋‹น์žฅ ์–ด๋–ค router๋กœ ์ด.. 2023. 12. 10.
[๋„คํŠธ์›Œํฌ] 5.3 ์ธํ„ฐ๋„ท์—์„œ์˜ AS ๋‚ด๋ถ€ ๋ผ์šฐํŒ…: RIP, OSPF Routing protocol์ด ์—„์ฒญ ๋‹ค์–‘ํ•˜๋„ค? ์ด๋Ÿฌํ•œ routing algorithm์—๋Š” ๋ฌธ์ œ๊ฐ€ ๋งŽ๋‹ค...ํ™•์žฅ์„ฑ ๋ฌธ์ œAdministrative autonomy (ํ–‰์ • ์ž์น˜) ๋ฌธ์ œ: ๋…์ž์„ฑ์„ ๋ณด์žฅ๋ฐ›๊ณ  ์‹ถ๋‹ค! --> Autonomous Systems (AS)Hierarchical routing: Autonomous Systems (AS)โ–ท ํ•˜๋‚˜์˜ AS ์•ˆ์—์„œ๋Š”:๋™์ผํ•œ routing policy๋ฅผ ์ ์šฉํ•œ๋‹ค.Single ownsership ํ•˜์— ์žˆ๋‹ค.Unique 32-bit integer AS number (ASN)์— ์˜ํ•ด ์‹๋ณ„๋œ๋‹ค. Internet approach to scalable routing: ์‹ค์งˆ์ ์œผ๋กœ๋Š” ๊ฐ AS์— ๋งˆ๋‹ค ์ž์‹ ๋งŒ์˜ ๊ณ ์œ ํ•œ routing protocol์„ ๊ฐ–๋Š”๋‹ค. โ–ถ Routing pr.. 2023. 12. 10.