I have searched the internet but I am not finding any sort of answer to this, in fact most threads die off when someone brings this up.
(show ver provided at bottom for switch model / platform being used, in short it is a 3750v2 running IOS 15.0(2)SE9)
So I have 4 interfaces that are DTP enabled on my switch, which there are 4 ports in use (2 Trunks and 2 unconfigured Access ports) per "sh dtp":
SW1(config-if)#do sh dtp
Global DTP information
Sending DTP Hello packets every 30 seconds
Dynamic Trunk timeout is 300 seconds
4 interfaces using DTP
So I added "switchport nonegotiate" to interface Fa1/0/1 which is configured as "switchport mode trunk", confirmed on the remote switch that it is not receiving DTP Hellos from Fa1/0/1 using "debug dtp events", however I still see this in my switch output:
SW1#sh dtp int
DTP information for FastEthernet1/0/1:
TOS/TAS/TNS: TRUNK/NONEGOTIATE/TRUNK
TOT/TAT/TNT: 802.1Q/802.1Q/802.1Q
Neighbor address 1: 000000000000
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
Oddly enough I tried throwing a configuration on one of the access ports to also make it "nonegotiate", and it still show in the "sh dtp" as an enabled DTP interface, however when I look at the individual interface I see this:
DTP information for FastEthernet1/0/11:
TOS/TAS/TNS: ACCESS/OFF/ACCESS
TOT/TAT/TNT: NATIVE/NEGOTIATE/NATIVE
Neighbor address 1: 000000000000
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: S1:OFF
# times multi & trunk 0
Enabled: no
In STP: no
It shows in the TAS field OFF where it would say AUTO by default, and it also shows it is not DTP Enabled, though it still shows in "sh dtp" # of interfaces.
So my questions are if any of you switching experts can shed some light here:
1. Why is the Trunk interface showing it is DTP Enabled, when it is clearly set to NONEGOTIATE in the TAS (Trunking Admin Status)?
2. Why would the Access Port showing in "sh dtp int" included in the # of DTP enabled interfaces via "sh dtp"when it explicitly shows DTP is not enabled?
3. Is DTP truly disabled on Fa1/0/1 if it is showing as Enabled in "sh dtp int" ?
Here is the "sh run" of both Fa1/0/1 (Trunk) and Fa1/0/11 (Access) for clarity:
!
interface FastEthernet1/0/1
switchport trunk encapsulation dot1q
switchport mode trunk
switchport nonegotiate
!
...
!
interface FastEthernet1/0/11
switchport mode access
switchport nonegotiate
!
Here also is the "sh ver" for switch / IOS information:
SW1#sh ver
Cisco IOS Software, C3750 Software (C3750-IPSERVICESK9-M), Version 15.0(2)SE9, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2015 by Cisco Systems, Inc.
Compiled Tue 01-Dec-15 07:02 by prod_rel_team
ROM: Bootstrap program is C3750 boot loader
BOOTLDR: C3750 Boot Loader (C3750-HBOOT-M) Version 12.2(53r)SEY4, RELEASE SOFTWARE (fc1)
SW1 uptime is 18 minutes
System returned to ROM by power-on
System image file is "flash:/c3750-ipservicesk9-mz.150-2.SE9/c3750-ipservicesk9-mz.150-2.SE9.bin"
This product contains cryptographic features and is subject to United
States and local country laws governing import, export, transfer and
use. Delivery of Cisco cryptographic products does not imply
third-party authority to import, export, distribute or use encryption.
Importers, exporters, distributors and users are responsible for
compliance with U.S. and local country laws. By using this product you
agree to comply with applicable laws and regulations. If you are unable
to comply with U.S. and local laws, return this product immediately.
A summary of U.S. laws governing Cisco cryptographic products may be found at:
http://www.cisco.com/wwl/export/crypto/tool/stqrg.html
If you require further assistance please contact us by sending email to
export@cisco.com.
cisco WS-C3750V2-24PS (PowerPC405) processor (revision S0) with 131072K bytes of memory.
Processor board ID FDO1640X1W8
Last reset from power-on
1 Virtual Ethernet interface
24 FastEthernet interfaces
2 Gigabit Ethernet interfaces
The password-recovery mechanism is enabled.
512K bytes of flash-simulated non-volatile configuration memory.
Base ethernet MAC Address : 1C:E6:C7:C1:C8:00
Motherboard assembly number : 73-12633-01
Power supply part number : 341-0266-03
Motherboard serial number : FDO16400W2E
Power supply serial number : LIT1621081M
Model revision number : S0
Motherboard revision number : F0
Model number : WS-C3750V2-24PS-S
System serial number : FDO1640X1W8
Top Assembly Part Number : 800-33158-03
Top Assembly Revision Number : B0
Version ID : V08
CLEI Code Number : CMMEE00BRB
Hardware Board Revision Number : 0x02
Switch Ports Model SW Version SW Image
------ ----- ----- ---------- ----------
* 1 26 WS-C3750V2-24PS 15.0(2)SE9 C3750-IPSERVICESK9-M
Configuration register is 0xF
SW1#
Thank you so much for any input, will mark helpful answers!
