Switch Network Configuration Table

Now that the router network configuration table is complete, let’s move on to the switch
version of this table. More information on switches and switch commands is provided in
Chapter 41, “Troubleshooting Switched Ethernet.” As stated in the preceding section, in this
example we are assuming that there are about 20 switches in the network for which we are creating
documentation. In addition, we are working with switches that have only layer 2 functionality.
Based on this arrangement, we have decided to include the following list of items in
our switch network configuration table:
 Device Name
 Model #
 Location
 Flash

 DRAM
 CatOS Version
 Management Address
 VTP Domain
 VTP Mode
 Port Number
 Port Speed
 Port Duplex
 VLAN
 Spanning Tree Protocol (STP) State
 Portfast Status
 Trunk Status
The beginning of the switch network configuration table is shown in Figure 34.2.
As was the case with the network configuration table for routers, just a few commands are
needed to populate the table produced for the switches. Specifically, these commands are
 show version
 show interface
 show vtp domain, show port
 show trunk
 show spantree vlan
Note that the preceding are CatOS commands. The IOS equivalents of these
commands are show version, show interface, show vtp status, show
interface, show interfaces trunk, and show spanning-tree vlan, respectively.
More information about the differences between CatOS and IOS are
covered in Chapter 41.

The first of these commands, show version, operates similarly to the same command in the
router. It produces a number of the elements that are needed in order to populate the switch network
configuration table:
core_switch> (enable) show version
WS-C6509 Software, Version NmpSW: 6.4(3)
Copyright (c) 1995-2003 by Cisco Systems
NMP S/W compiled on Apr 10 2003, 17:33:25
System Bootstrap Version: 5.3(1)
Hardware Version: 2.0 Model: WS-C6509 Serial #: SCA123456F
PS1 Module: WS-CAC-1300W Serial #: SON01234564
PS2 Module: WS-CAC-1300W Serial #: SON01234569
Mod Port Model Serial # Versions
--- ---- ------------------- ----------- ----------------------------
1 2 WS-X6K-SUP1A-2GE SAD05430RPV Hw : 3.2
Fw : 5.3(1)
Fw1: 5.1(1)CSX
Sw : 6.4(3)
Sw1: 6.4(3)
WS-F6K-PFC SAD05430LYJ Hw : 1.1
3 48 WS-X6248-RJ-45 SAD04330N7Z Hw : 1.2
Fw : 5.1(1)CSX
Sw : 6.4(3)
7 24 WS-X6324-100FX-MM SAD0234523C Hw : 1.3
Fw : 5.4(2)
Sw : 6.4(3)
8 8 WS-X6408A-GBIC SAL43566W9J Hw : 2.0
Fw : 5.4(2)
Sw : 6.4(3)
DRAM FLASH NVRAM
Module Total Used Free Total Used Free Total Used Free
------ ------- ------- ------- ------- ------- ------- ----- ----- ----
1 65408K 48425K 16983K 16384K 9568K 6816K 512K 310K 202K
Uptime is 55 days, 11 hours, 28 minutes


As you can see in the underlined output, the show version command provides the CatOS
level of the switch, as well as the flash and DRAM information.
The next command, show vtp domain, reports both the VTP domain and the VTP mode of
the switch. (VTP [VLAN Trunk Protocol] is covered in more detail in Chapter 41.)
core_switch> (enable) show vtp domain
Domain Name Domain Index VTP Version Local Mode Password
----------------------- ------------ ----------- ----------- ----------
dover_core 1 2 Transparent -
Vlan-count Max-vlan-storage Config Revision Notifications
---------- ---------------- --------------- -------------
13 1023 0 enabled
Last Updater V2 Mode Pruning PruneEligible on Vlans
--------------- -------- -------- -------------------------
10.40.40.2 disabled disabled 2-1000
Once you have obtained the VTP data, the next piece of information needed is the management
interface IP address. This address is included as part of the output from the show interface command.
Notice that on a switch, the command displays far less information than for routers and
focuses only on the management interfaces, not on the user ports.
core_switch> (enable) show interface
sl0: flags=51
slip 0.0.0.0 dest 0.0.0.0
sc0: flags=63
vlan 2 inet 10.40.40.2 netmask 255.255.255.252 broadcast 10.40.40.3
By using a separate VLAN for the management VLAN, we ensure that management
traffic to or from the switch will not be directly affected by user traffic, and
vice versa. For further protection, a separate uplink instead of a common trunk
can be used for the management VLAN, as is shown in this example.
The next command that is used to populate the switch network configuration table is the show
port command, which provides a substantial amount of fairly concise information about each port
on the switch. Be aware, however, that the output can get very lengthy if there are a large number
of ports on the switch. For the purpose of the switch network configuration table, the port numbers,
VLAN (for nontrunked ports), duplex, and speed information can be obtained from this output:
core_switch> (enable) show port
Port Name Status Vlan Duplex Speed Type
----- ----------------- ---------- --------- ------ ----- -----------
1/1 core_switch_2 connected trunk full 1000 1000BaseSX


1/2 core_switch_2 connected trunk full 1000 1000BaseSX
3/1 server1 connected 45 full 100 10/100BaseTX
3/2 mgmt_tool1 connected 45 half 10 10/100BaseTX
3/3 server3 connected 45 a-full a-100 10/100BaseTX
3/4 notconnect 45 auto auto 10/100BaseTX
3/5 notconnect 45 auto auto 10/100BaseTX
3/6 notconnect 45 auto auto 10/100BaseTX
...
...

The output removed from the foregoing show port command includes more
than just additional port numbers, names, status, VLAN, duplex, speed, and
type. It contains packet statistics, error rates, security parameters, and much
more. This information was not shown here because it does not directly relate
to the switch network configuration table.
Because the VLAN information is not included in the output of a show port command for
a trunked port, we need to get this data in another manner. There are a couple of ways to get
this information, but the usual method is via the show trunk command:
core_switch> show trunk
* - indicates vtp domain mismatch
Port Mode Encapsulation Status Native vlan
-------- ----------- ------------- ------------ -----------
1/1 nonegotiate dot1q trunking 45
1/2 nonegotiate dot1q trunking 45
Port Vlans allowed on trunk
-------- -------------------------------------------------------------
1/1 1-2,45-46
1/2 1-2,45-46
Port Vlans allowed and active in management domain
-------- -------------------------------------------------------------
1/1 1-2,45-46
1/2 1-2,45-46
Port Vlans in spanning tree forwarding state and not pruned
-------- -------------------------------------------------------------
1/1 1-2,45-46
1/2 1-2,45-46

The VLANs that traverse the trunk are shown in the Vlans allowed on trunk section
of this output. If a VLAN is not listed in this section, then it will not be permitted on
the trunk.
The final command necessary to complete the information in the switch network configuration
table is the show spantree vlan command. In our case, we need information regarding
VLAN 45, the VLAN in which our servers reside.
core_switch> show spantree 45
VLAN 45
Spanning tree mode PVST+
Spanning tree type ieee
Spanning tree enabled
Designated Root 00-d0-f6-bc-aa-aa
Designated Root Priority 49152
Designated Root Cost 3004
Designated Root Port 1/1
Root Max Age 20 sec Hello Time 2 sec Forward Delay 15 sec
Bridge ID MAC ADDR 00-d0-f6-bc-7e-00
Bridge ID Priority 49152
Bridge Max Age 20 sec Hello Time 2 sec Forward Delay 15 sec
Port Vlan Port-State Cost Prio Portfast Channel_id
---------------- ---- ------------- --------- ---- -------- ----------
1/1 45 forwarding 4 32 disabled 0
1/2 45 blocking 4 32 disabled 0
3/1 45 forwarding 19 32 enabled 0
3/2 45 forwarding 100 32 enabled 0
3/3 45 forwarding 19 32 enabled 0
3/4 45 not-connected 19 32 disabled 0
3/5 45 not-connected 19 32 disabled 0
3/6 45 not-connected 19 32 disabled 0
...
...

Notice that this command provides the necessary information to complete the STP State and
the Portfast configuration columns of the table.
When both the router and switch network configuration tables are complete, we can move
on to creating the network topology diagrams.

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