Routing Table Structure
Routing table entries come from the following sources
- Directly connected networks
- Static routes
- Dynamic routing protocols
Level 1 Routes //co subnet <= subnet mask major network
- Supernet Route
- Default Route
- Network Route //Mang giu nguyen ko chia nho /8 /16 /24
- Parent Route //Ko co next hop, exit int
Level 2 Routes
- Child Route
Ultimate Route //La cac route day dc goi tin di nho 2 tham so next hop, exit int(tru Parent Route thi cac loai Route khac deu la Ultimate Route)
Classfull vs Classless
Classless
- Hien thi Subnet mask cua major (Ca Parent va Child)
- Co variably subnetted
Routing Table Lookup Process
- Dau tien khi nhan duoc goi tin voi dia chi dich
- Router se so sanh tu tren xuong duoi voi cac Route lv1 tru ra Default Route va Super Net (vi day la Route tong hop)
- Neu Route lv1 (chi xet Network Route va Parent Route) match voi goi tin thi (so luong bit lam net phu hop voi subnet).
- Network Route thi day goi tin di ngay
- Parent Route thi so sanh voi cac Child Route trong Parent Route
- Neu Child Route phu hop thi se day di, khi co nhieu Child Route phu hop thi se day duong nao match nhieu bit nhat – Longest bit match
- Neu Child Route khong phu hop thi se xet den qua trinh behavior //co cho su dung classfull hay classless hay khong
- Neu behavior la classfull thi drop
- Neu behavior la classless. So sanh Supernet ma match thi day goi tin. Neu khong thi day theo Default route. Neu khong co Supernet hay Default Route thi drop
