What is span port on Cisco switch?
Port Mirroring also known as SPAN (Switch Port Analyzer), are designated ports on a network appliance (switch), that are programmed to send a copy of network packets seen on one port (or an entire VLAN) to another port, where the packets can be analyzed. SPAN Ports: Provide access to packets for monitoring.
What is the difference between Span and Rspan?
Local SPAN: Mirrors traffic from one or more interface on the switch to one or more interfaces on the same switch. RSPAN allows you to monitor traffic from source ports distributed over multiple switches, which means that you can centralize your network capture devices.
Can you span a trunk port?
When you monitor a trunk port as a source port, all VLANs active on the trunk are monitored by default. You can use VLAN filtering in order to limit SPAN traffic monitoring on trunk source ports to specific VLANs.
What is the purpose of Erspan?
ERSPAN Overview. The Cisco ERSPAN feature allows you to monitor traffic on one or more ports or more VLANs, and send the monitored traffic to one or more destination ports. ERSPAN sends traffic to a network analyzer such as a Switch Probe device or other Remote Monitoring (RMON) probe.
What port does Erspan use?
ERSPAN Destination Ports. A destination port is a Layer 2 or Layer 3 LAN port to which ERSPAN sends traffic for analysis. When you configure a port as a destination port, it can no longer receive any traffic and, the port is dedicated for use only by the ERSPAN feature.
How can I increase the number of SPAN ports?
Another way of increasing SPAN ports is to get a dedicated switch to send the SPAN traffic to; this dedicated switch will then give you the option of creating two more SPAN ports from the single SPAN source. Just watch out for any topology changes with a configuration like this.
How does span affect the performance of a switch?
Whether one or several ports eventually transmit the packet has absolutely no influence on the switch operation. Therefore, considering this architecture, the SPAN feature has no impact on the performance. Setting up a SPAN port is one thing, making sense of the data it provides is another.
What happens when a packet is dropped from a SPAN port?
This will result in some dropped packets on the destination port. However, this does not cause any switch performance degradation or disruption or traffic flow on the source ports. The only affected port is the destination port, and it drops packets on a first in first out (FIFO) basis once the egress buffer limit is exceeded.
Where do you find a SPAN port on a switch?
SPAN ports are typically found on network switch gear and the feature is used to send a copy of network packets seen on one switch port (or an entire VLAN) to another switch port.