Trunking issue between Cisco Switches ( 3750 and 6509 )

[dayibqalib]

HI Everyone 

Ports aren't coming up between 3750 and Cisco 6509 Switches: 

Cable used:  UTP 5e cable

Port Configuration on both ends are shown below:

------------------------------------------------------

6509 Switch port config

interface GigabitEthernet1/34

no ip address

logging event link-status

speed 100

switchport

switchport trunk native vlan 999

switchport trunk allowed vlan 380,999

switchport mode trunk

6509

APW-BTI-00-DR-ASW-01#show interfaces gigabitEthernet 1/34

GigabitEthernet1/34 is down, line protocol is down (notconnect)

  Hardware is C6k 1000Mb 802.3, address is 0012.803e.c191 (bia 0012.803e.c191)

  MTU 1500 bytes, BW 100000 Kbit, DLY 10 usec,

     reliability 255/255, txload 0/255, rxload 0/255

  Encapsulation ARPA, loopback not set

  Half-duplex, 100Mb/s

  input flow-control is off, output flow-control is desired

  Clock mode is auto

 -----------------------------------------------------------------

3750 port config

interface GigabitEthernet1/0/31

switchport trunk native vlan 999

switchport trunk allowed vlan 380,999

switchport mode trunk

speed 100

end

----------------------

3750

GigabitEthernet1/0/31 is down, line protocol is down (notconnect)

  Hardware is Gigabit Ethernet, address is 001c.0ecc.121f (bia 001c.0ecc.121f)

  MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Auto-duplex, 100Mb/s, media type is 10/100/1000BaseTX

-----------------------------------------------------------------------------

Please advice where the issue might be and thanks in advance 

[Leo Laohoo]

switchport trunk native vlan 999

switchport trunk allowed vlan 380,999

switchport mode trunk

Where is the encapsulation command:  switchport trunk encapsulation [dot1q/isl] for both sides? 

speed 100

Remove this line.  This is an old-school method of doing something stupid.

[dayibqalib]

HI Leo 

Thanks for you response, I have removed the Speed 100, however  I am not able to add the

switchport trunk encapsulation  dotq  on the 6509 switch it won't allow my to type encapsulation dot1q.

Could you please also let me know what the correct cable connection should be at the moment I am using cat5e.

Many thanks 

[Leo Laohoo]

 I am not able to add the switchport trunk encapsulation  dotq  on the 6509 switch it won't allow my to type encapsulation dot1q.

There are certain line card that won't accept the command because the default value is "dot1q" for encapsulation. 

Could you please also let me know what the correct cable connection should be at the moment I am using cat5e.

On the 3750, do a TDR test on the cable.

[dayibqalib]

HI Lao

is mandatory to use a crossover cable between 6509 and 3750 or can it autosense like some newer switches do ?

[Leo Laohoo · Accepted solution]

If the speed and duplex settings are set to default, MDI/MDI-X will kick in and when this happens straight-through or cross-over cables won't make a difference as long as each pins are terminated correctly.