CCIE Routing & Switching v5 Workbook -
CCIE R&S v5 Advanced Technology Labs -
LAN Switching
DTP Negotiation
A Note On Section Initial Configuration Files: You must load the
initial configuration files for the section, named Basic Layer2
Switching, which can be found in
. Reference the Virtual Routers & Physical
Switches Diagram to complete this task.
Task
Configure static 802.1q trunk links between SW1 and all other switches.
Disable Dynamic Trunking Protocol on all of these ports.
Configure all other inter-switch links between SW2, SW3, and SW4 to be in dynamic
auto state.
For verification, ensure that trunk links between SW1 and all other switches do not
use DTP.
Configuration
SW1:
interface range FastEthernet0/19 - 24
switchport trunk encapsulation dot1q
switchport mode trunk
switchport nonegotiate
SW2:
interface range FastEthernet0/19 - 22
switchport mode dynamic auto
!
interface range FastEthernet0/23 - 24
switchport trunk encapsulation dot1q
switchport mode trunk
switchport nonegotiate
SW3:
interface range FastEthernet0/19 - 20
switchport trunk encapsulation dot1q
switchport mode trunk
switchport nonegotiate
!
interface range FastEthernet0/21 - 24
switchport mode dynamic auto
SW4:
interface range FastEthernet0/19 - 20
switchport mode dynamic auto
!
interface range FastEthernet0/21 - 22
switchport trunk encapsulation dot1q
switchport mode trunk
switchport nonegotiate
!
interface range FastEthernet0/23 - 24
switchport mode dynamic auto
Verification
DTP negotiation can be disabled with either the
switchport mode access
command or
the
switchport nonegotiate
command. If trunking is needed but DTP is disabled, the
port must be statically configured with the
switchport mode trunk
command. This
design is most commonly used when a switch is trunking to a device that does not
support DTP, such as an IOS router’s routed Ethernet interface (not an EtherSwitch
interface) or a server’s NIC card.
SW1#show interface fastethernet0/19 switchport | include Negotiation
Negotiation of Trunking: Off
!
!SW1#show interface trunk
PortMode
Encapsulation StatusNative vlanFa0/19on
802.1q
trunking
1Fa0/20on
802.1q
trunking
1Fa0/21on
802.1q
trunking
1Fa0/22on
802.1q
trunking
1Fa0/23on
802.1q
trunking
1Fa0/24on
802.1q
trunking
1
<output omitted>
!
!SW2#show interface trunk
PortMode
Encapsulation
Status
Native vlanFa0/23on
802.1q
trunking
1Fa0/24on
802.1q
trunking
1
<output omitted>
!
!SW3#show interface trunk
PortMode
Encapsulation
Status
Native vlanFa0/19on
802.1q
trunking
1Fa0/20on
802.1q
trunking
1
<output omitted>
!
!SW4#show interface trunk
PortMode
Encapsulation
Status
Native vlanFa0/21on
802.1q
trunking
1Fa0/22on
802.1q
trunking
1
<output omitted>
Verify DTP statistics on both DTP-enabled and DTP-disabled interfaces, and note
that interface access/trunk state is displayed.
SW2#show dtp interface fastEthernet0/19
DTP information for FastEthernet0/19:
TOS/TAS/TNS:
ACCESS/AUTO/ACCESS
TOT/TAT/TNT:
NATIVE/NEGOTIATE/NATIVE
Neighbor address 1:
001AA1742515
Neighbor address 2:
000000000000
Hello timer expiration (sec/state):
15/RUNNING
Access timer expiration (sec/state):
never/STOPPED
Negotiation timer expiration (sec/state): never/STOPPED
Multidrop timer expiration (sec/state): never/STOPPED
FSM state:
S2:ACCESS
# times multi & trunk
0
Enabled:
yes
In STP:
no
Statistics
----------
372 packets received (372 good)
0 packets dropped
0 nonegotiate, 0 bad version, 0 domain mismatches,
0 bad TLVs, 0 bad TAS, 0 bad TAT, 0 bad TOT, 0 other
748 packets output (748 good)
374 native, 374 software encap isl, 0 isl hardware native
0 output errors
0 trunk timeouts
1 link ups, last link up on Wed Mar 24 1993, 12:07:57
0 link downs
!
!
SW2#show dtp interface fastEthernet0/23
DTP information for FastEthernet0/23:
TOS/TAS/TNS:
TRUNK/NONEGOTIATE/TRUNK
TOT/TAT/TNT:
802.1Q/802.1Q/802.1Q
Neighbor address 1:
0013605FF019
Neighbor address 2:
000000000000
Hello timer expiration (sec/state):
never/STOPPED
Access timer expiration (sec/state):
never/STOPPED
Negotiation timer expiration (sec/state): never/STOPPED
Multidrop timer expiration (sec/state): never/STOPPED
FSM state:
S6:TRUNK
# times multi & trunk
0
Enabled:
yes
In STP:
no
Statistics
----------
243 packets received (243 good)
0 packets dropped
0 nonegotiate, 0 bad version, 0 domain mismatches,
0 bad TLVs, 0 bad TAS, 0 bad TAT, 0 bad TOT, 0 other
247 packets output (247 good)
244 native, 3 software encap isl, 0 isl hardware native
0 output errors
0 trunk timeouts
3 link ups, last link up on Wed Mar 24 1993, 13:06:13
2 link downs, last link down on Wed Mar 24 1993, 13:05:34