10 Half Duplex???

[VN2Pro]

1 Switch Catalyst 2900 và 1 Switch 3COM 3300. Card mạng để auto detect thì sẽ là 100MB??? vậy mà lại không chạy. Chỉ khi chuyển sang 10 Half Duplex mới ăn....Chuối thật. Nhờ các cao thủ võ lâm của VNPro chỉ giáo...Xin đa tạ...

[leminhkhoi]

chào VN2Pro,
Sao khó hiểu quá, bạn gắn máy tính vào switch nào? Cisco hay 3Com, biểu hiện ra sao?
Mong có thêm thông tin
Thân chào

[VN2Pro]

Chào bạn. Tôi đã thử gắn máy tính vào cả hai cái Switch trên đều không chạy. Nó chỉ chịu work khi config cái card mạng về 10 Half Duplex. Tôi đã thử để 100 Full Duplex, 100 Half Duplex, 10 full duplex đều không chạy. Chẳng lẽ mấy cái card mạng này dỏm??? Tôi lấy thử cái Hub/Switch Planet nó chạy đúng 100 luôn. Hay nó chỉ thích làm việc với mấy cái thứ rẻ tiền này nhỉ?

[leminhkhoi]

chào,
Bạn thủ kiểm tr lại cáp có bấm đúng chuẩn không nếu cáp ok thì bạn hãy disable các chức năng trong card mạng như là flow control, 802.1p support,..
Làm thủ và cho kết quả nhé.
thân chào

[Saigon,Vietnam]

VN2pro,

On Catalyst Ethernet ports, the default mode is autonegotiate and, if autonegotiation fails, then is half-duplex. The lowest speed is set.

Bạn hardcode duplex và speed của switch ports thi hiện tượng trên sẽ hết.
Dưới dây là trích doạn soạn cho course troublesooting (switch ports connections):

This section walks you through examining the behavior of a 10/100-Mb Ethernet port that supports autonegotiation. It will also show how to make changes to its default behavior and how to restore it to the default behavior.

The following steps are performed on the console of a Catalyst 5K switch.

Step 1 The show port capabilities 1/1 command displays the capabilities of a Ethernet 10/100BaseTX 1/1 port on Switch A.

Switch-A> (enable) show port capabilities 1/1
Model WS-X5530
Port 1/1
Type 10/100BaseTX
Speed auto,10,100
Duplex half,full

Step 2 Autonegotiation is configured for both speed and duplex mode on port 1/1 of both switches by entering the set port speed 1/1 auto command (auto is the default for ports that support autonegotiation).

Switch-A> (enable) set port speed 1/1 auto
Port(s) 1/1 speed set to auto detect.
Switch-A (enable)

Step 3 The show port 1/1 command below displays the status of ports 1/1 on switches A and B.

Switch-A> (enable) show port 1/1
Port Name Status Vlan Level Duplex Speed Type
----- ------------------ ---------- ---------- ------ ------ ----- ------------
1/1 connected 1 normal a-full a-100 10/100BaseTX
Switch-B> (enable) show port 1/1
Port Name Status Vlan Level Duplex Speed Type
----- ------------------ ---------- ---------- ------ ------ ----- -----------
1/1 connected 1 normal a-full a-100 10/100BaseTX

The "a-" prefixes on the "full" and "100" indicate that this port has not been hard-coded for a specific duplex mode or speed.
Also note that the status shows "connected" on both ports, which means that a link pulse has been detected from the other port. The status can show "connected" even if duplex has been incorrectly negotiated or misconfigured.

Step 4 To demonstrate what happens when one link partner is autonegotiating and the other link partner is not, the speed on port 1/1 in Switch A will be set to 10 Mb by using the set port speed 1/1 10 command.

Switch-A> (enable) set port speed 1/1 10
Port(s) 1/1 speed set to 10Mbps.
Switch-A> (enable)

Entering the set port speed 1/1 10 command caused the duplex mode on port 1/1 to be configured as if the command set port duplex 1/1 full had also been entered.

Step 5 The absence of the "a-" prefix in the status fields of the output from the show port 1/1 command on Switch A shows that the duplex mode is now configured for full-duplex operation, and the speed is now configured for 10 Mb.

Switch-A> (enable) show port 1/1
Port Name Status Vlan Level Duplex Speed Type
----- ------------------ ---------- ---------- ------ ------ ----- ------------
1/1 connected 1 normal full 10 10/100BaseTX

Step 6 The show port 1/1 command on Switch B indicates that the port is now operating at half-duplex and 10 Mb.
Switch-B> (enable) show port 1/1
Port Name Status Vlan Level Duplex Speed Type
----- ------------------ ---------- ---------- ------ ------ ----- ------------
1/1 connected 1 normal a-half a-10 10/100BaseTX

This step shows that it is possible for a link partner to detect the speed at which the other link partner is operating, even though the other link partner is not configured for autonegotiation. Sensing the type of electrical signal that is arriving to see if it is 10 Mb or 100 Mb does this. This is how Switch B determined that port 1/1 should be operating at 10 Mb.

It is not possible to detect the correct duplex mode in the same way that the correct speed can be detected. On Catalyst Ethernet ports, the default mode is autonegotiate and, if autonegotiation fails, then is half-duplex.

Port 1/1 on Switch A is configured for full-duplex operation, while port 1/1 on Switch B has defaulted to half-duplex operation. To avoid this, always configure both link partners.

The "a-" prefix on the Duplex and Speed status fields does not always mean that the current behavior was negotiated. Sometimes it means only that the port has not been configured for a speed or duplex mode.

The previous output from Switch B shows the Duplex field as "a-half" and the Speed field as "a-10," which indicates that the port is operating at 10 Mb in half-duplex mode.

Step 7 The following message about a duplex mode mismatch is displayed on Switch A after the speed on port 1/1 was changed to 10 Mb. The mismatch was caused by Switch B's 1/1 port defaulting to half-duplex mode because it sensed that its link partner was no longer performing autonegotiation.
%CDP-4-DUPLEXMISMATCH:Full/half duplex mismatch detected o1
It is important to note that this message is created by the Cisco Discovery Protocol (CDP), not the 802.3 autonegotiation protocol. CDP can report problems that it discovers, but it typically doesn't automatically fix them.
A duplex mismatch may or may not result in an error message.

Hy vọng có kết qủa,

[VN2Pro]

Thanks Saigon, vietnam! Cái article của bạn rất clear. tôi đã thử và bây giờ thì OK rồi. VNPro thật tuyêt!