Cisco 7604 User Manual

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Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 52 Configuring Local SPAN, RSPAN, and ERSPAN
Local SPAN, RSPAN, and ERSPAN Configuration Guidelines and Restrictions
• Fabric channel
• Rewrite/replication engine
• Forwarding engine (PFC/DFC)
To avoid disrupting traffic, do not oversubscribe any of these points in your SPAN topology. Some
oversubscription and performance considerations are:
• SPAN doubles traffic internally
• SPAN adds to the traffic being processed by the switch fabric
• SPAN doubles forwarding engine load
• The supervisor engine handles the entire load imposed by egress SPAN (also called transmit SPAN).
Note Egress SPAN should only be enabled for short periods of time during active troubleshooting
• The ingress modules handle the load imposed by ingress SPAN sources (also called receive SPAN)
on each module. Ingress SPAN adds to rewrite/replication engine load.
Feature Incompatiblities
These feature incompatibilities exist with local SPAN, RSPAN, and ERSPAN:
• Egress SPAN is not supported in egress multicast mode. (CSCsa95965)
• With a PFC3, EoMPLS ports cannot be SPAN sources. (CSCed51245)
• A port-channel interface (an EtherChannel) can be a SPAN source, but you cannot configure active
member ports of an EtherChannel as SPAN source ports. Inactive member ports of an EtherChannel
can be configured as SPAN sources but they are put into the suspended state and carry no traffic.
• With releases earlier than Release 12.2(33)SXH, a port-channel interface (an EtherChannel) cannot
be a SPAN destination.
• You cannot configure active member ports of an EtherChannel as SPAN destination ports. Inactive
member ports of an EtherChannel can be configured as SPAN destination ports but they are put into
the suspended state and carry no traffic.
• Because SPAN destination ports drop ingress traffic, these features are incompatible with SPAN
destination ports:
– Private VLANs
– IEEE 802.1X port-based authentication
– Port security
– Spanning tree protocol (STP) and related features (PortFast, PortFast BPDU Filtering, BPDU
Guard, UplinkFast, BackboneFast, EtherChannel Guard, Root Guard, Loop Guard)
– VLAN trunk protocol (VTP)
– Dynamic trunking protocol (DTP)
– IEEE 802.1Q tunneling
Note SPAN destination ports can participate in IEEE 802.3Z Flow Control.

Cisco 7604 Specifications

General

Brand	Cisco
Model	7604
Category	Network Router
Language	English