Hoi dap ve mang may tinh

Tags: cong nghe khong day, Mang khong day, mang ngang hang, mang may tinh, thiet bi, su dung, cau hoi, co the, chat luong, khai niem, viec, lam, cap, ban, diem

Ngay nay, internet da khong con la khai niem xa la. Song co nhieu nguoi thuong xuyen tiep xuc voi no con chua hieu duoc ban chat cua mang khong day, mang Intranet hay mang ngang hang... Tra loi ban doc TS, Cisco Bachkhoa dua ra nhung kien thuc tong hop nhat ve cac van de cu the tren

Cau hoi 1: Mang may tinh khong day la gi?

Hoi dap ve mang may tinh
Mang khong day can ban.

Tra loi:

Co rat nhieu khai niem ve mang khong day, sau day toi dua ra mot khai niem ma co the co cai nhin khai quat duoc phan nao ve no: Mang khong day su dung song radio hay song cuc ngan de duy tri cac kenh truyen thong giua cac thiet bi truyen thong voi nhau, va nhu vay co the hieu mang may tinh khong day la mang khong day truyen thong giua cac may tinh voi nhau. Mang khong day co nhieu mo hinh khac so voi mang co day, mang ma su dung cap dong hay cap quang … de ket noi cac thiet bi voi nhau.

Mot mang khong day mang den nhieu uu diem ben canh do cung co nhieu nhuoc diem so voi mang co day duoc neu o mot vai diem sau:

Uu diem cua mang khong day do la tinh di dong va loai bo duoc su ruom ra cua viec di cap.

Nhuoc diem cua mang khong day co the ke den nhat la kha nang nhieu song radio do thoi tiet, do cac thiet bi khong day khac, hay cac vat chan (nhu cac nha cao tang, dia hinh doi nui…).

Mang khong day nhanh chong tro nen pho bien doi voi ca mang gia dinh va mang cho muc dich thuong mai.

Cong nghe khong day van tiep tuc duoc cai thien, va gia thanh cua cac san pham khong day tiep tuc giam. Cac san pham WLAN noi tieng hien nay lai phu hop voi chuan 802.11 “Wi-Fi”. Do la su vuot troi cua cong nghe khong day so voi cong nghe co day. Nhung lieu cong nghe khong day trong tuong lai co thuc su thay the cho cong nghe co day hay khong thi do van la mot cau hoi khong de de tra loi!

Co cau thiet bi ma mot nguoi can de xay dung mot mang khong day bao gom nhieu thu, nhung co the ke den nhung thiet bi quan trong nhu la: NICs, Access Points, va Router.

Cau hoi 2: Su khac nhau giua mot Client va mot Server la gi, va mo hinh mang Client/Server la gi?

Tra loi: Clients va Servers la cac thiet bi thuc hien cac chuc nang dac trung tren mang. Cac thiet bi Client thong thuong yeu cau va nhan thong tin tren mang. Cac may tinh xach tay va hau het cac may tinh ban van hanh nhu cac Client. Mot thiet bi goi la Server khi no lam chu cac tap tin, lam chu cac co so du lieu, cac Web site hay cac ung dung khac. Cac thiet bi Server thuong co bo vi xu ly voi toc do cao, co nhieu bo nho, va dia cai dat lon hon so voi cac Client.

Thuat ngu Client/Server ngu y toi bat ky mot mang nao thiet ke su dung cac Client va cac Server. Web, FTP, email, DNS va nhieu ung dung co so du lieu khac la cac thiet ke theo kieu Client/Server. Cac mang Client/Server co the duoc xay dung tren Internet, trong Intranet, hay tai nha.

Su khac biet chinh cua mang Client/Server so voi mang ngang hang la, trong mang ngang hang (pear – to – pear) cac thiet bi truyen thong tren mang co vai tro nhu nhau, chung vua la thiet bi cung cap tai nguyen cho mang vua la thiet bi su dung tai nguyen cua mang.

Cau hoi 3: Mang ngang hang la gi?

Tra loi: Mang ngang hang la mot kieu mang duoc thiet ke cho cac thiet bi trong do co chuc nang va kha nang cua cac thiet bi do la nhu nhau. Mang ngang hang don gian cung duoc biet den bang viec so sanh voi mang Client/Server, mang ma trong do chua cac thiet bi chiu trach nhiem cung cap hay phuc vu thong tin mang va cac thiet bi khac se su dung cac tai nguyen mang hay noi cach khac chung nhu cac Client cua cac Server nay. Mang ngang hang pho bien o trong nhung mang LAN nho, dien hinh la mang Window gia dinh. Mang ngang hang tren Internet da dat duoc nhieu thanh cong nhat dinh dac biet trong dich vu chia se file (nhu Napster). Tuy nhien, nhieu dich vu chia se file, ke ca Napster, tren thuc te duoc tich hop trong ca mang ngang hang lan mang Client/Server. Ve mat ky thuat, day duoc goi la cac mang lai (Hybrid).

Cau hoi 4: Co cach nao de truyen file giua hai may tinh su dung cap khong co modem khong?

Tra loi: Cau tra loi cho cau hoi tren la “co”! Loai cap nay cho phep ban thiet lap viec chia se file giua hai may tinh bang viec ket noi qua cong noi tiep hoac cong song song cua chung. Thuat ngu tieng anh “null modem” den tu viec nhin nhan kha nang cua cap do lam duoc nhung gi, loai cap nay cung cap cho mang mot toc do cham vua phaima khong can su dung modem.

Cap khong co modem khong yeu cau cac may tinh co card Ethernet. Boi ly do nay, chung la mot dang rat pho bien cua ket noi cap truc tiep (Direct Cable Connection) giua cac may tinh.

Cau hoi 5: Lam the nao de do duoc chat luong cua mot mang?

Tra loi: Chat luong cua mot mang o day nguoi ta quan tam nhat do la mang do “chay nhanh” hay khong, vi vay khi noi den chat luong cua mot mang nguoi ta thuong nghi den toc do cua mang do, do vay chat luong cua mot mang duoc khai niem la mot dai luong dac trung co don vi la bit/giay (bps). Con so nay co the the hien mot toc do thuc te dat duoc hay mot gioi han ve ly thuyet ve bang thong cua mang hien thoi.

Cac mo hinh mang ho tro mot so rong lon bps. Thay vi dua ra cac con so rong lon nhu “kilobit”, “megabit”, va “gigabit”.

· 1 Kbps = 1kbps = 1 kilobit per second = 1000 bits per second

· 1 Mbps = 1000 Kbps

· 1 Gbps = 1000 Mbps

Trong linh vuc mang, co the su dung chu hoa hoac chu thuong de bieu thi don vi, vi du co the dung “kbps” hoac “Kbps”.

Ve mat ky thuat, toc do mang duoc su dung de do dung luong cua cac dia va bo nho cua may tinh. Khong can lam phuc tap van de nay lam gi ca. Dung luong la dai luong dac trung co don vi la “kilobytes”, “megabytes”, va “gigabytes”. Trong cach dung nay, chu ‘K’ in hoa the hien mot so nhan cua 1024 va chu ‘k’ thuong bieu thi mot so nhan cua 1000. Cac phuong trinh sau giai thich ve mat toan hoc dang sau cac thuat ngu nay:

· 1KB = 1024 bytes

· 1kB = 1000 bytes

· 1MB = 1024 KB

· 1 GB = 1024 MB

Cau hoi 6: Mang Intranet la gi, no khac voi cac loai mang khac o cho nao (vi du Internet)?

Hoi dap ve mang may tinh
Intranet va Internet

Tra loi:

Mot Intranet la mot mang LAN rieng duoc thiet ke cho viec su dung boi tat ca moi nguoi ben trong mot to chuc. Mot Intranet don gian bao gom mot mot he thong mail noi bo hay mot bang thu tin. Co nhieu mang Itranet phuc tap bao gom nhieu cong Web site co chua cac tin tuc, cac hinh dang, va thong tin ca nhan cua cong ty. Ve mat ban chat cua mot Intranet la su dung cac cong nghe LAN (va WAN) de thuan loi cho viec truyen thong giua moi nguoi va cai thien co so nhan thuc ve cac nhan cong cua mot cong ty.

Cau hoi 7: “Toi co mot Netgear hub ket noi voi bon may tinh. Chung khong chia se ket noi Internet nhung chung su dung mang de choi games. IPX game nhu Starcraft lam viec tot nhung TCP/IP games lai co van de. IP kiem tra bieu hien cac goi bi mat la khoang 25%. Van de nay duoc la nhu the nao?”

Tra loi: IPX la tot hon cho viec choi game boi vi tong chi phi cua no von da rat thap. Voi tat ca luong da phuong tien, 25% goi TCP/IP mat di voi mot hub Ethernet la chuyen binh thuong, va vi vay ban hoan toan co the gap van de ve chat luong voi mang do.

De cai thien chat luong ban nen thay the hub ma ban dang su dung bang mot Switch: Nhu ban da biet thi hub chi quang ba va lap lai nhung gi ma chung da lang nghe, trong khi do thi Switch cung cap mot cach day du bang thong va co hoi cua cac va cham (collission) xay ra la khong con, Switch lam duoc dieu nay la vi no gan nhu tao ra mot lien ket diem - diem giua hai phuong tien truyen thong trong mang.

Ban moi nghien cuu ve mang may tinh va co nhung thac mac can giai dap, hay gui cau hoi theo mau ben duoi, Cisco Bach Khoa se tu van va tra loi nhung thac mac cua ban thong qua muc Networking cua VietnamNet ICT :

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Tìm hiểu: cong nghe khong day, Mang khong day, mang ngang hang, mang may tinh, thiet bi, su dung, cau hoi, co the, chat luong, khai niem, viec, lam, cap, ban, diem
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