CCNP TSHOOT 6.0 - Cisco Learning Home
CCNP TSHOOT 6.0 - Cisco Learning Home
CCNP TSHOOT 6.0 - Cisco Learning Home
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<strong>CCNP</strong>v6 <strong>TSHOOT</strong><br />
Sample Multilayer Switching<br />
Troubleshooting Flow<br />
Locate failing<br />
Layer 3 hop<br />
Verify<br />
ingress<br />
Layer 3<br />
interface<br />
Check<br />
control plane<br />
data<br />
structures<br />
Verify routing table<br />
and ARP cache<br />
Check<br />
packet<br />
switching<br />
data<br />
structures<br />
© 2009 <strong>Cisco</strong> Systems, Inc. All rights reserved. <strong>TSHOOT</strong> v1.0—34<br />
Verify the Routing Table and ARP Cache<br />
The next step in this process is to verify that the control plane information that is necessary to forward the packets<br />
is present. The two control plane data structures that are relevant to multilayer switching are the routing table and<br />
the ARP cache.<br />
In this sample troubleshooting flow, the multilayer switching data structures for an Internet Control Message<br />
Protocol (ICMP) echo request traveling from source IP address 10.1.50.1 to destination IP address 10.1.202.1 is<br />
verified by using various show commands.<br />
DLS1#show ip route 10.1.202.1<br />
Routing entry for 10.1.202.1/32<br />
Known via "eigrp 1", distance 90, metric 2300416, type internal<br />
Redistributing via eigrp 1<br />
Last update from 10.1.2.2 on FastEthernet0/5, 02:41:16 ago<br />
Routing Descriptor Blocks:<br />
* 10.1.2.2, from 10.1.2.2, 02:41:16 ago, via FastEthernet0/5<br />
Route metric is 2300416, traffic share count is 1<br />
Total delay is 25100 microseconds, minimum bandwidth is 1544 Kbit<br />
Reliability 255/255, minimum MTU 1500 bytes<br />
Loading 1/255, Hops 2<br />
DLS1#show ip arp 10.1.2.2<br />
Protocol Address Age (min) Hardware Addr Type Interface<br />
Internet 10.1.2.2 162 001b.530d.60b1 ARPA FastEthernet0/5<br />
DLS1#show interfaces FastEthernet 0/5 | include bia<br />
Hardware is Fast Ethernet, address is 0017.5a5b.b442 (bia 0017.5a5b.b442)<br />
In the output, you can see that a route is found in the routing table for the destination IP address 10.1.202.1, and<br />
the next hop and outbound interface for packets with that destination are listed.<br />
If the routing table does not contain an entry (specific prefix or default route) for the destination, the problem is not<br />
a packet-switching problem but a routing problem, and you should initiate a process to troubleshoot the routing<br />
operation on the control plane.<br />
All contents are Copyright © 1992–2010 <strong>Cisco</strong> Systems, Inc. All rights reserved. This document is <strong>Cisco</strong> Public Information. Page 16 of 26
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