S2 C10 Link-State Routing Protocols

Link-State Routing //Dijkstra

Dijkstra’s SPF (Shortest Path First) //khong co khai niem load blancing

Metric = cost //tinh bang bang thong – bang thong lon thi cost cang be

5 buoc de mang hoi tu

  • Hoc cac duong ket noi truc tiep voi Router //giong cold stat
  • OSPF Hello packets – trao doi tat ca cac link-state (thuoc tinh cua link: network, ip, kieu mang, chi phi, neighbor) cua minh voi hang xom voi hang xom va nhan ban tin tu hang xom ve
  • Sau khi nhan duoc thong tin link-state hang xom va cua minh, Router se xay dung goi tin Link State Packet (LSP) bao gom thong tin cua minh va hang xom
  • Flood ban tin LSP cho tat ca cac Router hang xom
  • Router hang xom se copy 1 ban LSP cho minh de lam CSDL route va Flood ban tin LSP day cho cac Router hang xom
  • Qua trinh nay lap lai khi router nhan day du cac LSP cua cac Router tren he thong mang. Router se chay thuat toan SPF de tinh duong di tot nhat trong mang

Ban tin Database Description de kiem tra thong tin dong bo giua cac Router de kiem tra day du thong tin

Implementing Link-State Routing Protocols

Uu diem:

  • Hoi tu nhanh vi //khong phai quang ba, khi flood xong va nhan day du LSP thi moi tinh toan
  • Khong update theo chu ky, chi update theo su kien
  • Hoat dong tot tren cac mo hinh mang lon tren mo hinh phan cap //Distance Vector hoat dong tren mo hinh ngang hang va hinh tron

Nhuoc diem:

  • He thong mang qua lon thi chay Link-state rat mat thoi gian vi ban tin LSP qua nhieu //Khac phuc bang cach chia area, mang backbone va router bien
  • Tieu ton nhieu tai nguyen phan cung: ram, cpu
  • Ton bang thong de flood
  • Qua trinh hoat dong phuc tap voi 5 buoc
  • Quan ly cau hinh kho khan hon

//Rick Graziani Cabrilo College