Difference between revisions of "CCNP TSHOOT Learning Guide/Chapter 4"

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==Troubleshooting Spanning Tree==
 
==Troubleshooting Spanning Tree==
−
 
+
===Example===
 +
'''insert figure 4-9 on page 112'''
 +
#Elect a root bridge
 +
##based in lowest [[Spanning_tree_protocol#BID_or_Bridge_Identifier|BID]]
 +
#Select a root port on each switch.
 +
##Least cost to [[Spanning_tree_protocol#Selection_of_Root_Bridge|Root]] bridge
 +
###Ties broken by lowest upstream [[Spanning_tree_protocol#BID_or_Bridge_Identifier|BID]]
 +
###Further ties are broken by lowest port ID
 +
#Elect a designated device/port on each network segment
 +
##Based on lowest cost to Root bridge.
 +
###Ties are broken on [[Spanning_tree_protocol#BID_or_Bridge_Identifier|BID]]
 +
###Further ties are broken by lowest port ID
 +
#Ports that ended up as neither a root port nor a designated port go into [[Spanning_tree_protocol#STP_Port_States|blocking] state
 
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{{Source cli}}

Revision as of 10:23, 15 June 2010

Kate.png This article is under development....

Maintaining and troubleshooting Campus Switched Solutions

VLAN Troubleshooting

Layer 2 reviewing

ARP

  • show mac-addresses
SW1#<input>show mac-address-table</input>
          Mac Address Table
-------------------------------------------

Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
 All    0100.0ccc.cccc    STATIC      CPU
 All    0100.0ccc.cccd    STATIC      CPU
<notice>...OUTPUT OMITTED...</notice>
   1    001b.0cba.4f99    DYNAMIC     Gi0/9
   1    001b.2a32.2e99    DYNAMIC     Gi0/5
   1    0021.5a7c.5549    DYNAMIC     Gi0/4
   1    00a0.d1e6.60b4    DYNAMIC     Gi0/22
  41    0014.f273.96c0    DYNAMIC     Gi0/7
<notice>...OUTPUT OMITTED...</notice>
  41    001b.0cb6.9141    DYNAMIC     Gi0/7
  41    001b.0cba.4fc1    DYNAMIC     Gi0/9
  41    001b.2a32.2ec1    DYNAMIC     Gi0/5
  12    001f.297d.3460    DYNAMIC     Gi0/2
  20    00a0.c543.035d    DYNAMIC     Gi0/6
  22    0003.47ca.d67c    DYNAMIC     Gi0/7
  22    000c.296c.1120    DYNAMIC     Gi0/12
  24    0016.769f.ff4e    DYNAMIC     Gi0/8
  28    0013.2085.a1fe    DYNAMIC     Gi0/9
  28    0013.2085.c447    DYNAMIC     Gi0/9
<notice>...OUTPUT OMITTED...</notice>

Troubleshooting layer 2

  • Hardware issues (move cable to good port)
  • VLAN configuration.
    • Inter-VLAN traffic must be routed
  • Trunk configuration
    • Same trunkprotocol (DOT1Q,ISL)
    • Same Native VLAN

Verifying Layer 2 Forwarding

Often used commands

  • show mac-address-table
  • show vlan
  • show interface trunk
  • show interface switchport
  • show platform forward interface - Example below
  • traceroute mac - Example below

show platform forward interface example

Show how the switch will direct traffic 

SW1#<input>show platform forward gigabitEthernet 0/1 vlan 1 0021.5a7c.5549 001b.2a32.2e99</input>
Ingress:
Global Port Number: 1, lpn: 3 Asic Number: 1
Source Vlan Id: Real 1, Mapped 1. L2EncapType 0, L3EncapType 3
Hashes: L2Src 0x00 L2Dst 0x09 L3Src 0x00 L3Dst 0x09
 Lookup                   Key-Used                  Index-Hit    A-Data
Classify 68_0070001B_2A322E99-00_00000021_5A7C5549     00FFC   00000000
InputACL 20_0070001B_2A322E99-00_00000021_5A7C5549     01FF8   01000000
L2LrnMsk FF_03FFFFFF_FFFFFFFF-00_000003FF_00000000
L2Learn  83_00010021_5A7C5549-93_00000401_00000000     01840   00000000
L2FwdMsk FF_03FFFFFF_FFFFFFFF
L2Fwd    83_0001001B_2A322E99                          0003E   000000C5
Station Descriptor: F005F001, DestIndex: F005, RewriteIndex: F001
==========================================
Egress: Asic 0, switch 1
Source Vlan Id: Real 1, Mapped 1. L2EncapType 0, L3EncapType 3
portMap 0x4, non-SPAN portMap 0x4

Output Packets:
------------------------------------------
GigabitEthernet0/5 Packet 1
 Lookup                   Key-Used                  Index-Hit    A-Data
OutptACL 30_0070001B_2A322E99-00_00000021_5A7C5549     01FFC   01000000

Port       Vlan      SrcMac          DstMac    Cos  Dscpv
Gi0/5      0001 0021.5a7c.5549  001b.2a32.2e99

traceroute mac

Did not work out all right. 

SW1#<input>traceroute mac 001b.0c5d.42c2 0006.5bc5.2dfb</input>
l2trace error response received : 3 from 192.168.4.22
Layer2 path not through SW2 [192.168.4.22].
Layer2 trace aborted.

Troubleshooting Spanning Tree

Example

insert figure 4-9 on page 112

  1. Elect a root bridge
    1. based in lowest BID
  2. Select a root port on each switch.
    1. Least cost to Root bridge
      1. Ties broken by lowest upstream BID
      2. Further ties are broken by lowest port ID
  3. Elect a designated device/port on each network segment
    1. Based on lowest cost to Root bridge.
      1. Ties are broken on BID
      2. Further ties are broken by lowest port ID
  4. Ports that ended up as neither a root port nor a designated port go into [[Spanning_tree_protocol#STP_Port_States|blocking] state
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