GBIC Link between 3550 switches

[LanworX]

Hi,

I am trying to connect two Cisco 3550 switches using the Gi0/1 interfaces. I am assuming that i need to setup a trunk between the two switches over this L2 connection, but I seem to have a more fundamental problem than that.

After inserting a 1000SX GBIC module into the switch i would have exected the interface state to go from down to up, but it doesn't> do i have to do something first to "turn on" the GBIC? Without a cable connected i can see that the transmission LED is on, but the switch isn't recognsing the GBIC

I am running IOS 12.1(19)EA1c

What am i doing wrong ?

 

[sirlollypop]

No the interface will still be down until you connect it to another gbic. Once the pair are connected you will see the interfaces come up/up.

If you loop the gbic back on itself you will see it go up for a second then go done error disabled as it can see it's own keepalive come back on itself

 

[LanworX]

OK just did a loopback and i saw the interface come up and then go to diable state as you said.

GigE ports are configured thus

interface GigabitEthernet0/1
switchport trunk encapsulation dot1q
switchport mode trunk
no ip address

one swith cis set to VTP server the other client, and both are memebers of the same VTP domain.

What am i missing ?

 

[rmcp2k]

can you give us the sh run config?

did you setup a vtp password?

 

[LanworX]

Nope i didn't set a VTP password.

Which part of the config do you need ?

 

[rmcp2k]

the whole config if you can and also the "sh vtp status" output.

 

[LanworX]

The running config is this:-

sh run
Building configuration...

Current configuration : 3670 bytes
!
version 12.1
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname BLK_Testbench
!
enable secret 5 $1$mRmQ$ilou5JNSyHmZE2HQa6P/W/
enable password
!
ip subnet-zero
ip routing
!
!
spanning-tree mode pvst
spanning-tree extend system-id
!
interface GigabitEthernet0/1
switchport trunk encapsulation dot1q
switchport mode trunk
no ip address
!
interface GigabitEthernet0/2
switchport access vlan 103
switchport mode dynamic auto
no ip address
!
interface Vlan1
no ip address
shutdown
!
interface Vlan101
ip address 192.168.101.101 255.255.255.0
!
interface Vlan103
ip address 192.168.103.254 255.255.255.0
!
interface Vlan104
ip address 192.168.104.254 255.255.255.0
!
router rip
version 2
redistribute static
network 192.168.101.0
network 192.168.103.0
network 192.168.104.0
!
ip classless
ip route 0.0.0.0 0.0.0.0 192.168.101.254
ip route 192.168.100.0 255.255.255.0 192.168.101.254
ip http server
!
end

And the VTP status

BLK_Testbench#sh vtp sy t
VTP Version : 2
Configuration Revision : 0
Maximum VLANs supported locally : 1005
Number of existing VLANs : 8
VTP Operating Mode : Server
VTP Domain Name : testbench
VTP Pruning Mode : Disabled
VTP V2 Mode : Disabled
VTP Traps Generation : Disabled
MD5 digest : 0xB4 0x58 0xF0 0xCC 0x73 0x16 0xA9 0x64
Configuration last modified by 192.168.101.250 at 6-14-94 08:15:47
Local updater ID is 192.168.101.101 on interface Vl101 (lowest numbered VLAN interface found)

Hope that's enough info for you.

 

[vipergg]

Try entering the command "switchport nonegotiate" on each side and see what happens .

 

[LanworX]

Nope that had no effect. Still have no link lights on and int gi0/1 still down/down.

Is it better to set the ports to ISL rather than dot1q?

 

[sirlollypop]

as you have vlan1 shut. Try adding some vlans to the trunk

int g0/1
switchport trunk allowed vlan 101

you should then see the vlan come up.

Also post a:

sh span
&
sh int g0/1

 

[rmcp2k]

switchport nonnegotiate" will not do anything as you already static the trunk mode.


if its switchport mode trunk, all vlans belong to that trunk. which he has three other vlan(s) beside the native vlan.


ISL is cisco proprierty and dot1q is standards. you can use ISL if you want if you have all cisco equipments. Do1q is use for multi vendors and is the prefer.

can you do a "sh int trunk" to and see if GI/01 is acutally trunking.

 

[LanworX]

Thanks for all your help guys (and gals) but I have solved my problem!

I have configured the gi0/1 port as so

no switchport
ip address 192.168.102.103/24

and similarly at the other end and the the link has come up! transferrifn routing over the link using RIPv2 and all seems to be well.

Whew !