Cisco ASR-920-4SZ-D User Manual

If only one port on a router is configured in a segment, the port should be an edge port.
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If two ports on a router belong to the same segment, both ports must be edge ports or must be
regular segment ports.
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If two ports on a router belong to the same segment and one is configured as an edge port and the
other as a regular segment port (a misconfiguration), the edge port is treated as a regular segment
port.
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REP interfaces come up in a blocked state and remain in a blocked state until they are safe to be unblocked.
You need to be aware of this status to avoid sudden connection losses.
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REP ports cannot be configured as one of the following port types:
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Switched Port Analyzer (SPAN) destination port
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Private VLAN port
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Tunnel port
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Access port
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There can be a maximum of 22 REP segments per router.
REP Support on a Trunk EFP
Resilient Ethernet Protocol (REP) can be configured on Trunk EFP ports at the interface level on Cisco ASR
920 Series Router. Trunk EFP ports can have several bridged VLAN services running on them. Trunk EFP
supports only 1000 VLANs. VLANs can be set to blocking and forwarding state on a Trunk EFP port. A user
must enable REP on a port. By default, REP is disabled on all ports.
REP Configurable Timers
In a ring network topology, the Fast Last Link Status (LSL) process detects a neighboring port and maintains
a connection with it. The timer on a port can be configured within 200-10000 ms to receive LSL frames. If
no LSL frames are received from 200 to10000 ms from the neighboring port, the link between routers is
considered as down. The tear-down operation and action is taken to bring up the link and restore traffic.
In the ring network topology, REP might fail to converge the traffic within 50 ms. For example, if the topology
is made of copper cable, REP might fail to converge the traffic due to hardware limitations of the copper
interface. In such a scenario, a remote end can take up to 700 ms to detect shutdown failure of a local port.
The REP LSL is enhanced to achieve higher timer granularity and faster failure detection on the remote side.
LAN Switching Configuration Guide Cisco IOS XE Everest 16.5.1 (Cisco ASR 900 Series)
16
Configuring Resilient Ethernet Protocol
REP Support on a Trunk EFP

Cisco ASR-920-4SZ-D Specifications

General

Brand	Cisco
Model	ASR-920-4SZ-D
Category	Network Router
Language	English