Specifications

Cisco ONS 15454 Product Overview
Ethernet
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Cisco ONS 15454 Product Overview, R3.3
May 2002
802.1 Q-tag standard. You can switch tagged traffic onto separate SONET STS
channels to engineer bandwidth by traffic class. The ONS 15454 can also concentrate
Ethernet ports into one or more STS-N circuits to use bandwidth more efficiently.
Priority Queuing
Networks without priority queuing handle all packets on a first-in-first-out basis.
Priority queuing, which is supported by the ONS 15454, reduces the impact of
network congestion by mapping Ethernet traffic to different priority levels. The
ONS 15454 takes the eight priorities specified in IEEE 802.1Q and maps them to
two queues. Q-tags carry priority queuing information through the network.
VLAN Service
The ONS 15454 works with Ethernet devices that do and do not support IEEE
802.1Q tagging. The ONS 15454 supports virtual LANs that provide private network
service across a SONET backbone. You can define specific Ethernet ports and
SONET STS channels as a VLAN group. VLAN groups isolate subscriber traffic
from users outside the VLAN group and keep “outside” traffic from “leaking” into the
virtual private network (VPN). Each IEEE 802.1Q VLAN represents a different
logical network.
Spanning Tree Protocol
The ONS 15454 uses the IEEE 802.1D standard to provide spanning tree protocol
(STP). STP detects and eliminates network loops; the ONS 15454 uses spanning tree
protocol internally and externally. Internally, it detects multiple circuit paths between
any two network ports and blocks ports until only one path exists. The single path
eliminates possible bridge loops.
Externally, you can enable spanning tree at the Ethernet-port level to allow parallel
connections to external networking equipment. Spanning tree will only allow one
connection to be used at any given time. You can disable spanning tree protection on
a circuit-by-circuit basis on unstitched Ethernet cards in a point-to-point
configuration.