Cisco Cisco Agent Desktop 8.5
References
June 21, 2004
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Appendix A SPAN Overview
The VoIP Monitor service relies on a SPAN (Switched Port ANalyzer) session
configured on the Catalyst switch. A SPAN session is a feature of the Cisco
Catalyst switches that allows one or more port’s IP traffic to be copied and sent
to another single destination port on the switch.
configured on the Catalyst switch. A SPAN session is a feature of the Cisco
Catalyst switches that allows one or more port’s IP traffic to be copied and sent
to another single destination port on the switch.
The ports that are used for the input to a SPAN are referred to as source ports.
The port where all the copied traffic is sent is called the destination port.
The port where all the copied traffic is sent is called the destination port.
NOTE
On some switches, the SPAN destination port is referred to as the
monitor port. In this document this port will always be referred to as the
destination port.
destination port.
Think of SPAN as a funnel that collects network traffic from multiple ports and
copies it to a single output port. The destination port of a SPAN is used by the
VoIP Monitor service to sniff for voice traffic to and from agent phones.
copies it to a single output port. The destination port of a SPAN is used by the
VoIP Monitor service to sniff for voice traffic to and from agent phones.
Depending on the switch model, the source ports used by SPAN can be ports
or VLANs. Only certain types of ports can be used as source ports.
or VLANs. Only certain types of ports can be used as source ports.
Using switch ports as source ports is referred to as PSPAN (Port SPAN).
Using VLANs as source ports are referred to as VSPAN (VLAN SPAN). Some
switches support only PSPANs. Other switches support both PSPANs and
VSPANs. Some switches support the use of both ports and VLANS in a single
SPAN configuration.
Using VLANs as source ports are referred to as VSPAN (VLAN SPAN). Some
switches support only PSPANs. Other switches support both PSPANs and
VSPANs. Some switches support the use of both ports and VLANS in a single
SPAN configuration.
Local SPANs (LSPANs) are SPANs where all the source ports and the destina-
tion port are physically located on the same switch. Remote SPANs (RSPANs)
can include source ports that are physically located on another attached
switch.
tion port are physically located on the same switch. Remote SPANs (RSPANs)
can include source ports that are physically located on another attached
switch.
The number of SPANs that can be configured can vary by switch. SPAN con-
figuration and functionality is not the same on all Cisco Catalyst switches.
figuration and functionality is not the same on all Cisco Catalyst switches.
Some switches can have the SPAN destination port configured to only show
packets that are incoming to the source port(s) (ingress traffic) or only packets
that are outgoing to the source port(s) (egress traffic). The default for many
switches is to show both ingress and egress packets hitting the source port(s).
packets that are incoming to the source port(s) (ingress traffic) or only packets
that are outgoing to the source port(s) (egress traffic). The default for many
switches is to show both ingress and egress packets hitting the source port(s).
On some Catalyst switches, the destination port of a SPAN will not accept reg-
ular network traffic. In these cases, the machine running the VoIP Monitor ser-
vice must have two NIC cards; one to send and receive normal network traffic,
and another to receive voice traffic from the switch.
ular network traffic. In these cases, the machine running the VoIP Monitor ser-
vice must have two NIC cards; one to send and receive normal network traffic,
and another to receive voice traffic from the switch.
For more information on SPAN and RSPAN, refer to your switch documenta-
tion.
tion.