There are other instance of (theoretically) multi-access serial interfaces, such as SDLC, but that is enough for now.

That is why in Frame Relay, you either have to have a static ARP mapping, or rely on frame-relay inverse-arp, or tie the (sub-)interface to a single MAC address with frame-relay interface-dlci. it is called the DLCI, or channel number. Does that have a MAC address? Well yes, it does, sort of. While an IP address can potentially be assigned to any device, a MAC address is burned in to a given device from the factory. If it is a straight point-to-point connection like HDLC, there is no need for a MAC address 'cos you know to send the packets to the guy at the other end of the link.īut consider a multi-access serial link like Frame Relay. A MAC address, sometimes referred to as a hardware address or physical address, is an ID code that’s assigned to a network adapter or any device with built-in networking capability (say, a printer). That is why a serial line doesn't have a MAC address. 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.Ī serial line has only two ends, so it is fairly obvious where to send the packets.

A MAC address is relevant in Multi-Access networks like Ethernet where you have several hosts on the same network. Let's take a step backwards and ask why a MAC address is not relevant on a serial interface.

Mac address of a printer