You can create SPAN sessions to designate sources and destinations to monitor.

See the Cisco Nexus 7000 Series NX-OS Verified Scalability Guide for information on the number of supported SPAN sessions.

This figure shows a SPAN configuration. Packets on three Ethernet ports are copied to destination port Ethernet 2/5. Only traffic in the direction specified is copied.

Cisco NX-OS Release 6.2(2) and later releases support extended SPAN sessions in addition to the two traditional SPAN sessions supported in prior releases. Extended SPAN sessions can be traditional or unidirectional. The session direction is specified during session creation. A pool of 12 independent session resources are available. Unidirectional sessions use one resource, and traditional sessions use two resources. These 12 resources are shared between local and SPAN source sessions across all VDCs.

If you are configuring an extended SPAN session on a Cisco Nexus 7710 switch or a Cisco Nexus 7718 switch, the following applies:

• The mode extended command must be used with the third configuration session.

• You can configure 16 sessions as unidirectional or bidirectional, as required.

• You do not need to maintain two traditional sessions.

• You do not need to use the resource manager to reserve the two traditional sessions.

Cisco NX-OS Release 7.3(0)D1(1) and later releases support 4K VLANs per SPAN session. You can use the source interface all command to enable the monitor session on the switch to monitor all VLANs and ports in the VDC such as physical ports, Port Channels, FEX ports and FEX Port Channels. The 4K VLANs per SPAN Session feature also enables monitoring of a higher number of specific VLAN sources than the VLAN source limits currently supported in the monitor session by using the filter vlan command with the source interface all command to filter the irrelevant VLANs.

Exception SPAN enables you to span exception packets. Packets that have failed an intrusion detection system (IDS), Layer 3 IP verification, and FabricPath are treated as exception packets.

Note

Beginning with Cisco NX-OS Release 6.2(10), you can remove the FabricPath and VLAN tag headers from SPAN packets. Use the system default switchport monitor exclude header and the switchport monitor exclude header commands. See the Cisco Nexus 7000 Series NX-OS Security Command Reference for more information on these commands.

An exception SPAN session is supported in either one of the two traditional bidirectional SPAN sessions or in one of the extended SPAN sessions. Rate limiters, MTU truncation, and sampling are supported in the exception SPAN session. Only the exception packets sent to the drop destination interface are supported as a SPAN source. Exception packets that are pushed to the supervisor, ACLQoS, or Layer 2 are not spanned. Each VDC supports one exception SPAN session.

Extended SPAN is supported in the egress direction only. In the case of an extended SPAN Rx session, the exception source configuration will be rejected.

You can create a virtual SPAN session to monitor multiple VLAN sources and choose only VLANs of

interest to transmit on multiple destination ports. For example, you can configure SPAN on a trunk port and monitor traffic from different VLANs on different destination ports.

The figure below shows a virtual SPAN configuration. The virtual SPAN session copies traffic from the three VLANs to the three specified destination ports. You can choose which VLANs to allow on each destination port to limit the traffic that the device transmits on it. In the figure below, the device transmits packets from one VLAN at each destination port.

Note	Virtual SPAN sessions cause all source packets to be copied to all destinations, whether the packets are required at the destination or not. VLAN traffic filtering occurs at the egress destination port level.

For information about configuring a virtual SPAN session see the Configuring a Virtual SPAN Session section.

You can also use the Cisco Network Analysis Module (NAM) to monitor SPAN data sources for application performance, traffic analysis, and packet header analysis.

To use NAM for monitoring the Cisco Nexus 7000 SPAN data sources, see the Cisco Nexus 7000 Series Network analysis Module (NAM-NX1) Quick Start Guide.

The SPAN feature supports stateless and stateful restarts. After a reboot or supervisor switchover, the running configuration is applied. For more information on high availability, see the Cisco Nexus 7000 Series NX-OS High Availability and Redundancy Guide.

A virtual device context (VDC) is a logical representation of a set of system resources. SPAN applies only to the VDC where the commands are entered.

For information about configuring VDCs, see the Cisco Nexus 7000 Series NX-OS Virtual Device Context Configuration Guide.

• For SPAN session limits, see the Cisco Nexus 7000 Series NX-OS Verified Scalability Guide.

• SPAN is not supported for management ports.

• All SPAN replication is performed in the hardware. The supervisor CPU is not involved.

• Link Aggregation Control Protocol (LACP) Port Channel is not supported as a SPAN destination.

  Note	Monitor session allows LACP PO to be added as SPAN destination even though the same is not supported. This does not impact any functionality.

• A destination port can only be configured in one SPAN session at a time.

• You cannot configure a port as both a source and destination port.

• If a module is not in the VDC in which the inband interface is sourced, packets destined to the supervisor cannot be captured.

• For Cisco NX-OS releases prior to 6.1, you can monitor the inband interface only from the default VDC. Inband traffic from all VDCs is monitored. Beginning with Cisco NX-OS Release 6.1, the monitoring of the inband interface is no longer restricted to the default VDC:

  • Only users with the network admin privilege can add the inband interface as a SPAN source.

  • The inband interface can be added as a source from any VDC except the admin VDC, but at any time, only one VDC can have the inband interface as a source.

• Inband SPAN is treated as a shared resource. If a particular VDC does not have the resource allocated to it, inband port sourcing is rejected. Similarly, if a VDC that has the inband supervisor resource allocated to it removes the inband port from the source list of all monitor sessions, the inband resource is released from that VDC.

• For the supervisor inband interface, SPAN is supported only in the VDC in which the inband interface is sourced. If a module is part of a VDC in which the inband interface is not sourced, at least one interface of the module must be in the VDC in which the inband interface is sourced in order to capture supervisor inband packets from this module.

• A single SPAN session can include mixed sources in any combination of the following:

  • Ethernet ports, but not subinterfaces

  • VLANs, that can be assigned to port channel subinterfaces

  • The inband interface to the control plane CPU

• When a SPAN session contains both source interfaces and source VLAN clauses, there is a possibility that other VLANs also will be spanned.

• Destination ports do not participate in any spanning tree instance. SPAN output includes bridge protocol data unit (BPDU) Spanning-Tree Protocol hello packets.

• When a SPAN session contains source ports or VLAN sources that are monitored in the transmit or transmit and receive direction, packets that these ports receive might be replicated to the SPAN destination port even though the packets are not actually transmitted on the source ports. Some examples of this behavior on source ports are as follows:

  • Traffic that results from flooding

  • Broadcast and multicast traffic

• You can enable SPAN for a source port before it becomes operationally active. Thus for Layer 2 ports, traffic flooded to the VLANs that contain these ports are captured even when the link is not connected for the ports.

• For VLAN SPAN sessions with both ingress and egress configured, two packets (one from ingress and one from egress) are forwarded from the destination port if the packets get switched on the same VLAN.

• Beginning with Cisco NX-OS Release 6.2(2), the spanning of inband interfaces is as follows:

  • For Supervisor 1 systems, the two bidirectional traditional sessions can support an inband SPAN source.

  • For Supervisor 2 and Supervisor 2e systems, all the SPAN sessions can support an inband SPAN source.

  • Only one VDC can support inband SPAN at a time.

• You can configure an RSPAN VLAN for use only as a SPAN session source.

• You can configure a SPAN session on the local device only.

• If you span a fabricpath core interface when inter-VLAN routing is enabled across Layer 2 multi-path (L2MP), it is not possible to capture the traffic egressing out of the core interface.

• SPAN is supported on Fabric Extender interfaces in Layer 2 access mode, Layer 2 trunk mode, and Layer 3 mode. Layer 3 subinterfaces are not supported.

• Cisco NX-OS does not span Link Layer Discovery Protocol (LLDP) or Link Aggregation Control Protocol (LACP) packets when the source interface is a Fabric Extender HIF (downlink) port or HIF port channel.

• SPAN sessions cannot capture packets with broadcast or multicast MAC addresses that reach the supervisor, such as ARP requests and Open Shortest Path First (OSPF) protocol hello packets, if the source of the session is the supervisor Ethernet in-band interface. To capture these packets, you must use the physical interface as the source in the SPAN sessions.

• The rate limit percentage of a SPAN session is based on 10G, 40G, and 100G for the respective modules (that is, 1 percent corresponds to 0.1G, 0.4G, or 1G respectively), and the value is applied per every forwarding engine instance.

• Beginning with Cisco NX-OS Release 6.1, SPAN is supported for Supervisor 2.

• SPAN does not capture pause frames in a Fibre Channel over Ethernet (FCoE) network because pause frames sent from the virtual expansion (VE) port are generated and terminated by the outermost MAC layer. For more information on FCoE, see the Cisco NX-OS FCoE Configuration Guide for Cisco Nexus 7000 and Cisco MDS 9500.

• On both Supervisor 1 and Supervisor 2, you cannot monitor the FCoE inband traffic.

• You can monitor both ingress and egress FCoE traffic can be monitored in a local SPAN session through Ethernet interfaces, including shared interfaces, or VLANs. For shared interfaces, you can monitor the FCoE traffic only in the storage VDC.

• The MAC in MAC (MiM) header in SPAN copies is preserved for the following SPAN destinations:

  • F2e modules with Release 6.2 or later releases.

  • F3 series modules with any Cisco NX-OS Release.

  • For F3 series modules with Release 6.2.(6a), 6.2.(6b), or 6.2(8), the Fabricpath (FP) header is preserved unconditionally. In Release 6.2.10, the FP header is preserved by default, but this behavior can changed by using the switchport monitor exclude header command to remove the FP or VLAN tag header for a specified SPAN destination in a VDC or the system default switchport monitor exclude header command to remove the FP or VLAN tag header for all destinations ports in the VDC. In Release 6.2.12, you can remove the FabricPath and VLAN tag headers using the switchport monitor exclude header command at the SPAN destination.

• The MiM header in SPAN copies is not preserved for the following SPAN destinations:

  • F1 and F2 series modules with any Cisco NX-OS Release.

  • F2e modules with Release 6.1(x).

  • For F3 series modules with Release 6.2.6, the FabricPath (FP) header is not preserved.

• Prior to Cisco NX-OS Release 7.2(0)D1(1), multiple SPAN destinations are not supported when an F Series module is present in a VDC. If multiple SPAN destinations are configured in a SPAN session, the session is disabled until the F Series module is powered down or moved to another VDC or the multiple SPAN destinations are reduced to a single destination.

  Starting from Cisco NX-OS Release 7.2(0)D1(1), multiple destination SPAN sessions are supported. Only the primary destination is used to transmit SPAN packets originated from Fx modules. Traffic from M series module goes to every destination port.

• A FabricPath core port is not supported as a SPAN destination when an F Series module is present in a VDC. However, a FabricPath core port can be configured as a SPAN source interface.

• F1 Series modules are Layer 2 domain modules. Packets from Layer 3 sources can be spanned and directed to an F1 Series module SPAN destination. An F1 Series module interface cannot be configured as Layer 3, but it can receive Layer 3 traffic in a SPAN destination mode.

• When using SPAN sessions on F1 Series or F2 Series modules, ensure that the total amount of source traffic in a given session is less than or equal to the capacity of the SPAN destination interface or port channel for that session. If the SPAN source traffic exceeds the capacity of the SPAN destination, packet drops might occur on the SPAN source interfaces. This guideline does not apply to F2e, F3 or M3 Series modules.

• MTU truncation and the SPAN rate limit are supported on F Series and M2 Series modules and Supervisor 2.

  Note

  You cannot enable MTU truncation and the SPAN rate limit for the same SPAN session on F1 Series modules. If you configure both for one session, only the rate limit is allowed on F1 Series modules, and MTU truncation is disabled until you disable the rate limit configuration. This limitation does not apply to F2 and M2 Series modules or Supervisor 2.

• For F1 Series modules, MTU truncation on egress spanned FabricPath (core) packets has 16 fewer bytes than the configured value because the SPAN destination removes the core header. In addition, when trunk ports are used as the SPAN destination, the spanned ingress packets have 4 more bytes than the configured MTU truncation size.

• For certain rate limit and packet size values on F Series modules, M2 Series modules, and Supervisor 2, the SPAN packet rate is less than the configured value because of the internal accounting of packet sizes and internal headers.

• SPAN sampling is supported only on F Series modules.

• Traditional SPAN sessions support traffic from the F Series and M Series modules. Extended SPAN sessions support traffic only from the F Series and M2 Series modules.

• F1 Series modules have limited support for rule-based SPAN. They do not support IPv6 source IP and IPv6 destination IP filters. They support only IPv4 and IPv6 ToS filters with values from 0 to 3. Port channel member lane, FCoE source ID, and FCoE destination ID are not supported.

• For certain rate limit and packet size values on F Series modules, M2 Series modules, and Supervisor 2, the SPAN packet rate is less than the configured value because of the internal accounting of packet sizes and internal headers.

• SPAN sampling is supported only on F Series modules.

• Traditional SPAN sessions support traffic from the F Series and M Series modules. Extended SPAN sessions support traffic only from the F Series and M2 Series modules.

• When the supervisor inband interface is monitored in the transmit direction on F2 Series modules, a 12-byte SHIM header is inserted after SMAC in SPAN packets.

• Prior to Cisco NX-OS Release 7.2(0)D1(1), multiple SPAN destinations are not supported when an F Series module is present in a VDC. If multiple SPAN destinations are configured in a SPAN session, the session is disabled until the F Series module is powered down or moved to another VDC or the multiple SPAN destinations are reduced to a single destination.

  Starting from Cisco NX-OS Release 7.2(0)D1(1), multiple destination SPAN sessions are supported. Only the primary destination is used to transmit SPAN packets originated from Fx modules. Traffic from M series module goes to every destination port.

• A FabricPath core port is not supported as a SPAN destination when an F Series module is present in a VDC. However, a FabricPath core port can be configured as a SPAN source interface.

• SPAN source functionality on satellite ports and host interface port channels is not supported when the FEX is connected to F2 or F2e Series modules.

• When using SPAN sessions on F1 Series or F2 Series modules, ensure that the total amount of source traffic in a given session is less than or equal to the capacity of the SPAN destination interface or port channel for that session. If the SPAN source traffic exceeds the capacity of the SPAN destination, packet drops might occur on the SPAN source interfaces. This guideline does not apply to F2e, F3 or M3 Series modules.

• VLANs containing FEX interfaces can be a SPAN source, but the ingress traffic through the F2 Series module-based FEX ports cannot be captured.

• F2 Series modules support FEX, but they do not support FEX SPAN. Therefore, the FEX interfaces connected through the F2 Series modules cannot be made SPAN sources.

• You can span Fabric port channels on F2 Series modules.

• Layer 3 multicast egress packets cannot be spanned on F2 Series modules.

• MTU truncation and the SPAN rate limit are supported on F Series and M2 Series modules and Supervisor 2. These features are not supported on M1 Series modules.

• For F2 Series modules, ingress FEX packets spanned through the Fabric port channel have 6 fewer bytes than the configured MTU size because the VNTag header is removed on the SPAN destination.

• For F2 Series modules, egress SPAN packets of all traffic that ingresses on Layer 2 ports (including edge-to-edge traffic) have 16 fewer bytes than the configured MTU size because a MAC-in-MAC header is added internally and removed at the SPAN destination.

• For F2, F2e, and F3 Series modules using SPAN destination port channels, SPAN traffic is distributed among the member ports. However, the distribution pattern can be different from that of regular (non-SPAN destination) port channels. For example, you can have even load distribution for regular port channels but uneven load distribution (or no load balancing) for SPAN destination port channels.

• For certain rate limit and packet size values on F Series modules, M2 Series modules, and Supervisor 2, the SPAN packet rate is less than the configured value because of the internal accounting of packet sizes and internal headers.

• SPAN sampling is supported only on F Series modules. It is not supported on M Series modules.

• Beginning with Cisco NX-OS Release 6.1, FCoE SPAN on F2 Series modules is supported for storage VDCs.

• Hardware session 15 is used by NetFlow on F2 and F2e Series modules. Any extended session using this hardware ID will not span incoming traffic on the F2 and the F2e ports.

• F2 and F2e Series modules have limited support for rule-based SPAN. They do not support wildcards in the IPv6 source IP filter and IPv6 destination IP filter. They do not support egress SPAN filtering for destination MAC addresses and source MAC addresses.

• For certain rate limit and packet size values on F Series modules, M2 Series modules, and Supervisor 2, the SPAN packet rate is less than the configured value because of the internal accounting of packet sizes and internal headers.

• SPAN sampling is supported only on F Series modules.

• Traditional SPAN sessions support traffic from the F Series and M Series modules. Extended SPAN sessions support traffic only from the F Series and M2 Series modules.

• Layer 3 multicast egress packets cannot be spanned on F3 Series modules.

• Prior to Cisco NX-OS Release 7.2(0)D1(1), multiple SPAN destinations are not supported when an F Series module is present in a VDC. If multiple SPAN destinations are configured in a SPAN session, the session is disabled until the F Series module is powered down or moved to another VDC or the multiple SPAN destinations are reduced to a single destination.

  Starting from Cisco NX-OS Release 7.2(0)D1(1), multiple destination SPAN sessions are supported. Only the primary destination is used to transmit SPAN packets originated from Fx modules. Traffic from M series module goes to every destination port.

• MTU truncation and the SPAN rate limit are supported on F Series and M2 Series modules and Supervisor 2.

• A FabricPath core port is not supported as a SPAN destination when an F Series module is present in a VDC. However, a FabricPath core port can be configured as a SPAN source interface.

• F3 Series modules do not support wildcards in the IPv6 source IP filters and the IPv6 destination IP filters.

• SPAN sampling is not supported on M Series modules.

• Traditional SPAN sessions support traffic from the F Series and M Series modules. Extended SPAN sessions support traffic only from the F Series and M2 Series modules.

• Beginning with Cisco NX-OS Release 5.2, you can configure the Cisco Nexus 2000 Series Fabric Extender (FEX) interfaces and the fabric port channels that are connected to the Cisco Nexus 2000 Series Fabric Extender as SPAN sources. However, you cannot configure them as SPAN destinations.

  Note	SPAN on Fabric Extender interfaces and fabric port channels is supported on the M1 Series and M2 Series modules. SPAN runs on the Cisco Nexus 7000 Series device, not on the Fabric Extender.

• If a port channel is the SPAN destination interface for SPAN traffic that is sourced from a Cisco Nexus 7000 M1 Series module, only a single member interface will receive copied source packets. The same limitation does not apply to SPAN traffic sourced from all other Cisco Nexus series modules, including the Cisco Nexus 7000 M1-XL Series modules.

• MTU truncation and the SPAN rate limit are not supported on M1 Series modules.

• Multicast best effort mode applies only to M1 Series modules.

• Extended SPAN sessions cannot source incoming traffic on M1 Series modules in either the ingress or egress direction.

• Traditional SPAN sessions support traffic from the F Series and M Series modules. Extended SPAN sessions support traffic only from the F Series and M2 Series modules.

• M1 Series modules and Supervisor 1 do not support rule-based SPAN. They support only VLAN filtering.

• M1 and M2 Series modules support exception SPAN only in the nonadministration VDC, and at least one interface of the module must be present for the VDC.

• Beginning with Cisco NX-OS Release 5.2, you can configure the Cisco Nexus 2000 Series Fabric Extender (FEX) interfaces and the fabric port channels that are connected to the Cisco Nexus 2000 Series Fabric Extender as SPAN sources. However, you cannot configure them as SPAN destinations.

  Note	SPAN on Fabric Extender interfaces and fabric port channels is supported on the M1 Series and M2 Series modules. SPAN runs on the Cisco Nexus 7000 Series device, not on the Fabric Extender.

• For certain rate limit and packet size values on F Series modules, M2 Series modules, and Supervisor 2, the SPAN packet rate is less than the configured value because of the internal accounting of packet sizes and internal headers.

• Packets may get dropped when the ingress SPAN configured on M2 module and on any other next gen line card module such as F3, M3 having SPAN destination ports; and if the configured monitor sessions on M2 modules and its hardware session IDs (check the show monitor resource session all command output for hw_ssn_id) are more than 11. To overcome this issue, shut down all the SPAN sessions/unconfigure and re-configure the sessions.

• SPAN sampling is not supported on M Series modules.

• Traditional SPAN sessions support traffic from the F Series and M Series modules. Extended SPAN sessions support traffic only from the F Series and M2 Series modules.

• M1 and M2 Series modules support exception SPAN only in the nonadministration VDC, and at least one interface of the module must be present for the VDC.

• For MTU truncation on M2 Series modules, the truncated length of SPAN packets is rounded down to the nearest multiplier of 16 bytes. For example, with an MTU configuration value of 65 to 79, packets are truncated to 64 bytes.

• Only eight sessions can support rate limiting on M2 Series modules. Any additional hardware sessions will not apply the configured rate limiter on M2 Series modules.

• M1 and M2 Series modules support exception SPAN only in the nonadministration VDC, and at least one interface of the module must be present for the VDC.

• Beginning with Cisco NX-OS Release 7.3(1)DX(1), SPAN is supported on M3 Series modules.

• SPAN sampling is supported on M Series modules and Supervisor 2.

• Extended SPAN sessions support traffic from M3 Series modules.

• If a monitor session has a source with both VLAN and a physical port, traffic may span on ports which may not be a part of the monitor session. This is applicable when M3-series I/O modules are used.

If you are working with a device connected to a SPAN destination port that does not understand FabricPath or VNTAG headers, you may want those headers stripped from the packet.

You can do this at either the global or port level. If you want to strip the headers to all SPAN destination ports in the VDC, you can apply the global command. If you want to apply the command only to a certain port, you can use the port-level command. If the ports are not SPAN destination ports, the command is rejected.

When you enter both the global and port-level configurations for this feature, the port-level overrides the global configuration.

Note	The port-level command overrides the global command. So you can configure the device to strip the headers globally and then issue the no form of the port-level command to exclude the specified ports from stripping the headers.