Network layer use 4 basic process:
- Addressing//Gan dia chi
- Encapsulation//Dong goi
- Routing //Tim duong di den dich dua tren dia chi
- Decapsulation //
Network Layer Protocols:
- Internet Protocol version 4 (IPv4)
- Internet Protocol versionn 6 (IPv6)
- Novell Internetwork Packet Exchange (IPX)
- Apple Talk
- Connectionless Network Service (CLNS/DECNet)
Basic characteristics:
- Connectionless //Phi ket noi (giong UDP
- Best Effort//Khong tin cay, khong can truyen lai
an unreliable protocol, does not have the capability to manage, and recover from, undelivered or corrupt packets. - Media Independent//Doc lap voi moi truong truyen phia duoi-moi truong nao cung hoat dong va giu nguyen dinh dang, cau truc goi tin va du lieu
Thay doi khi truyen tu Private IP<->Public IP
Thay doi khi MTU # nhau
IPv4 Header
- Ver //Cho biet v4 hay 6
- IHL //Do dai
- Service Type //Xac dinh kieu dich vu (QoS)
- Packet Length //Do dai cua ca Packet (H4+Data)
- Identification //Xac dinh mieng nho du lieu da chia thuoc goi nao ban dau
- Flag //co 3 bit
R: reserved
DF: cho biet goi tin co fragment ko
MF: cho biet mieng day co phai mieng cuoi cung hay chua - Fragment Offset //Cho biet vi tri cua mieng nho du lieu trong goi tin ban dau
- Time to Live //So luong tram trung gian dc phep di qua cua goi tin. -1 di qua 1 tram. Den 0 thi huy.
Windows 128, Unix 255, Linux 64 - Protocol //Giao thuc cua lop =4 hoac 6
- Header Checksum //Kiem tra tinh toan ven
- Source Address //IP nguon
- Destination Address //IP Dich
- Options //Truong cau hinh them
- Padding //Phan bu cua Option boi cua 32 bit
Segmenting //Chia nho du lieu o tang 4
Fragmenting //Chia nho goi tin o tang 3
Nmap zenmap
Group Devices
- De quan ly
- De bao mat
- De gan dia chi IP cho de hon
- Dua vao vi tri dia ly
- Muc dich
- Quyen han nguoi dung & may tinh
- Tranh xung dot khi gui nhieu ban tin Broadcast
Routing Metrics //Chi phi cua tuyen duong
Routed protocol:
Routing protocol: giao thuc cai tren router giup xac dinh duong di
Gateway: Dia chi cua router ma la noi cac goi tin trong 1 he thong mang di qua de sang mang khac. 1 mang co the co nhieu Gateway
Default Gateway: Gateway dc chi dinh duoc di ra
Next hop address: dia chi cua router tiep theo tren tuyen duong toi dich
Exit interface (out going interface): la cong de day goi tin ra //interface la cong cua router
Direct connected C
Static S
Dynamic D
Default route: la tuyen duong dung cho moi dich, thuong su dung khi o noi chi co 1 tuyen duong de di ra
