serial port

[amitchisti]

why serial port don't have mac address, and does it really create problem in frame relay when we configure access list.  what was the reason behind it that serial port don't have mac address.  why it broadcast first. 

[Richard Burts]

The first part of your question is straight forward - serial port does not have a mac address because serial protocols were developed that have a different mechanism for identifying the devices on the wire. So no mac address is needed for serial port.

The other part of your question is not clear to me. You ask about frame relay and access list. But it is not clear what you are really asking. An access list does not necessarily cause problems if applied to a serial interface. Depending on what is written in the access list it might cause a problem. I have seen lots of frame relay interfaces that had access lists applied and they work just fine.

HTH

Rick 

[Julio E. Moisa]

Hi

MAC address is used on Ethernet networks only. A MAC address is relevant in Multi-Access networks like Ethernet where you have several hosts on the same network. In such a network, you have to do an ARP broadcast to find the MAC address of the host, so you can send packets address to it and it only.

The serial interface works with encapsulations protocols by default HDLC is used on Cisco devices. 

[Joseph W. Doherty]

A "serial port" usually wouldn't have a BIA (burned in address) because if it has any address, it's usually assigned for/by a higher level protocol; if the protocol uses any kind of addressing.  As serial ports are often used in a true point-to-point topology, an address isn't often needed.

Conversely, Ethernet ports, which are designed to work with Ethernet protocols, need Ethernet addresses, MACs, even when used point-to-point.