Cisco CRS-1 - Carrier Routing System Router Troubleshooting Manual page 99

Chapter 3 Troubleshooting Forwarding
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DETAILED STEPS
Command or Action
Step 1
show interfaces interface name
Example:
RP/0/RP0/CPU0:router# show interface POS0/5/0/0
Step 2
show controller <ingressq|egressq> qmstats 0
location location-id
Example:
RP/0/RP0/CPU0:router# show controller ingressq
qmstats 0 location 0/12/cpu0
Step 3
show controller pse <ingress|egress> statistics
location location-id
Example:
RP/0/9/CPU0:router#show controller pse ingress
statistics loc 0/5/cpu0 | inc drop
RP/0/9/CPU0:EE10-1#show controller pse ingress
statistics loc 0/5/cpu0 | inc mtu
Step 4
show captured packets [ingress|egress] location
node_id
Step 5
show route <prefix> det
Example:
RP/0/RP0/CPU0:router# show route 20.20.1.2
OL-21483-02
show controller pse [ingress|egress] statistics location node-id
show captured packets [ingress|egress] location node_id
show route <prefix> det
show cef <prefix> det location location-id
show cef <prefix> hardware ingress detail location location-id
Contact Cisco Technical Support if the problem is not resolved
Troubleshooting Transient Traffic Drop in Forwarding
Purpose
Displays the packet count in the ingress and egress
interfaces before and after the transmission of packets.
If the packets are dropped either in ingress or egress
interface, then stop here and contact the Cisco Technical
Support team for troubleshooting the plim interfaces.
Checks the statistics in buffer management ASIC (BMA) at
both ingress and egress line cards before and after
transmission.
If you see any drop count incrementing other than soft drop,
then contact the Cisco Technical Support team for
resolution. If there is no increment in the drop count or only
the soft drop is incrementing, continue with the further
steps.
Displays the packets that are dropped at the packet
switching engine (PSE), the drop count, and maximum
transmission unit (mtu) count.
Ensure that the show command is executed multiple times
in order to check if the count is actually incrementing. To
check if the route has been removed and re-installed, you
must identify the traffic stream or prefix which experienced
the drop first.
Displays the packets which are dropped by the PSEs on the
line card. The next step is to find out what packets get
dropped. The debug command displays the L2 and L3
information of packets which are dropped by the PSE
microcode. When the captured packet is an MPLS packet,
you must look for the label of the packet. The label will be
used as the key to verify the forward chain. When the
captured packet is an IPv4 or IPv6 packet, you must look for
the destination address of the packet. The address is used as
the key to verify the forward chain of the prefix.
Checks the routing table and the timestamp provides you
information about when the route was installed.
Cisco IOS XR Troubleshooting Guide for the Cisco CRS-1 Router
3-89