And this was indeed, a true bus topology. Your basic consumer level 4-port or 8-port switch doesn't have this capability.īefore you had hubs, you had all nodes physically wired in and connected to a single physical thicknet or thinnet wire. On enterprise-level managed switches, you can do things like prevent a port from forwarding traffic of a different MAC other than the first that connected to it, and all kinds of other neat things. If it's not possible, it goes ahead and floods just like an old-school hub. Switches learn what MAC addresses are behind what ports, and will use this knowledge to avoid repeating traffic to each port (called "flooding") if possible. Other computers would ignore it, unless it was a broadcast. The destination computer would hopefully be elsewhere on that hub and get the traffic it wanted. When something sent traffic to a port on a hub, the hub would repeat the traffic out of every other port. As displayed in Figure 12-2, several Layer. Then you can use other switchport command keywords to configure trunking, access VLANs, and so on. So, that means that this address was in the CAM table and pointed to the uplink, and then moved to the Gig port. It doesn't generate a syslog when a mac-address is added or removed from the CAM table. (You can override this and put NICs into promiscuous mode where it will accept all packets, not just packets destined for it, if you want.) The switchport command puts the port in Layer 2 mode. The 'mac-address-table notification mac-move' command causes the switch to generate a syslog when a mac-address changes ports. Whenever the switch processes a packet, it makes a copy and sends it to whatever is connected to the aforementioned port. Then you configure the switch to mirror all traffic that passes through to that reserved port. This means each connected node assumes it will get traffic not intended for it, and thus will drop it if it's not addressed to it, or a broadcast packet. When you configure a switch, you reserve one port. The V1910-24G has a 56Gbps backplane, which is fast enough to support maximum traffic on all ports.Įthernet is designed with a bus topology in mind. With more than 24 ports or with ports faster than Gigabit, this starts to get expensive and that feature becomes rarer. Most modern Gigabit switches, managed and unmanaged, having 24 ports or fewer support full, non-blocking traffic on all ports. On some switches, there is an advantage to having devices that exchange a lot of traffic connected to the same switching module as that reduces backplane congestion. ![]() But on many of them, the backplane has some limit that is less than that. On some switches, the backplane (also known as the "switching fabric") is fast enough to support full, non-blocking traffic between all combinations of ports at full speed. If the switch has more than one switching module, the switching module also has some kind of "backplane" connector used to link the switching modules. 5-port and 8-port modules are common today. Each switching module typically has full, non-blocking connectivity between all of its ports. Modern switches, both low-end and high-end, are generally built out of one or more switching modules.
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