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WS-C3550-48-EMI not accept NIC MAC address start with 5XXX in 10M speed

WS-C3550-48-EMI not accept NIC MAC address start with 5XXX in 10M speed,but 100M is work fine. if i change the NIC's MAC address is ok also, the switch's ios is the last version.why? thanks !

3 REPLIES

Re: WS-C3550-48-EMI not accept NIC MAC address start with 5XXX i

A mac-adress is 6 bytes long and consists of a 3byte vendor code and a unique suffix, also 3 bytes long. Pls look at the following example:

The notation can be either 0000.1111.2222 or 000011.112222

What do you mean with: starting with 5xxx?

Is it 005xxx.112222 or 5xxx.1111.2222?

I would also like to know how you came to the conclusion that the range 5xxx is not accepted. This range contains 4096 possible adresses and I do not believe that you checked them all, so please explain.

Community Member

Re: WS-C3550-48-EMI not accept NIC MAC address start with 5XXX i

The address 5xxx.xxxx.xxxx is not accepted in 10M speed,thanks!

Community Member

Re: WS-C3550-48-EMI not accept NIC MAC address start with 5XXX i

The last bit of the first byte in a source-mac-address must be 0. So if your choosen address would start with 55xx this would be a fault according to this rule. last bit of first byte=1 means a group address. This is used only for destination addresses like in multicast oder broadcast messages

Willilam Boye, iuvandis GmbH

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