Most machines won't have anything listening for pure-ethernet connections, but you may still be able to map that MAC to an IP address. The payload is merely transmitted by TCP and "only the application cares".ĪRP is used when someone on the local network wants to send an IP packet, to an IP it doesn't have a MAC address for and is basically an ethernet-level broadcast saying "who has IP address blah?". The TCP header contains various control information, various flags (what part of the session is this, what's the sequence number, source and destination TCP ports. The IP header contains various control information, like source and destination IP and the encapsulated protocol (TCP, in this example). The ethernet header contains various control information, including the source and destination MAC addresses on the LAN. It may also (and usually does) have a "default gateway" (that is, an IP address through which it sends all packets going to somewhere other than a local subnet).Ībstractly, a packet destined for a web port looks something like: On the IP level, each machine has (at least) one IP, in (at least) one subnet. Note that a short aging time (for example, 1 minute) will cause MAC address entries to be aged outįast, and therefore result in traffic forwarding failures.īy default, dynamic secure MAC address entries learned by an interface are not aged out.IP addressing is at some level symbolic, usually relying on lower-level network protocols (with less hierarchic structure) to actually complete the transmission. The aging time of dynamic secure MAC address entries learned by the interface is set. (Optional) Run port-security protect-action ].(Optional) Run port-security mac-address mac-address vlan vlan-idĪ static secure MAC address entry is configured.The VLAN IDs in the two MAC address entries used by the IP phone are different. This is because the IP phone occupies two MAC address entries and the PC occupies one MAC address entry. If a PC connects to the switch using an IP phone, set the maximum number
0 kommentar(er)
