Troubleshooting Down Fabric Planes - Cisco CRS-1 - Carrier Routing System Router Troubleshooting Manual

Troubleshooting Down Fabric Planes

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Troubleshooting Down Fabric Planes
An individual link placed in a down state can be sustained without impact to the overall operation or
forwarding capacity of the Cisco CRS-1 Multishelf System. At each stage of the fabric, there is a greater
bandwidth capacity than can actually be generated by the modular services cards (MSCs). The egress
side of the switch fabric has at least double the capacity of the ingress.
The loss of a single link reduces the switch fabric capacity on a single plane by 2.5 Gbps or
approximately 1.5625 Gbps when considering 8b/10b encoding and cell tax overheads. The actual
effective loss of bandwidth varies depending on where the link loss takes place. If a link were to be lost
between the ingress queue and S1 stage or S1 and S2 stage, the reduction is against a capacity of 80 Gbps
or 50 Gbps effective bandwidth. A link loss between S2 and S3 stages or S3 and fabric queue stages
means that the reduction is against a capacity of 160 Gbps or 100 Gbps effective bandwidth.
Consider a situation in which a set of S1 links was lost on a single plane. Six or seven links would need
to be taken out of service in order to reduce the effective bandwidth capacity by approximately 10 Gbps.
It is, therefore, possible to contend that because the MSC is capable of transmitting at 40 Gbps, there is
still sufficient capacity to carry the traffic without loss.
The system is designed to operate with seven out of eight fabric planes in operation and provide full
line-rate forwarding capability, because it provides approximately 42 Gbps to each MSC. If another
fabric plane is removed, forwarding capacity would be reduced to approximately 34 Gbps.
SUMMARY STEPS
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Cisco IOS XR Troubleshooting Guide for the Cisco CRS-1 Router
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UP UP
UP UP
UP UP
UP UP
UP UP
UP UP
UP UP
UP UP
UP UP
admin
show controllers fabric plane all detail
Bring up the plane:
configure
a.
no controllers fabric plane plane-id shutdown
b.
end
c.
show running-config
show controllers fabric connectivity all
show controllers fabric sfe {s1 | s2 | s3 | ingressq | fabricq} all
show controllers fabric bundle port all
Chapter 4
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Troubleshooting Router Switch Fabric
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