Trunking question

Hi

I am doing a lab exercise in preparation for the BCMSN.

There is a 2950 access switch connected to two 3550 distribution
switches.

On the 2950, fa0/1 and fa0/2 are connected to 3550A and fa0/3 and fa0/4
are connected to 3550B.

At the moment, ports fa0/1 - 4 on the 2950 are in VLAN99.

The instructions are to -

i) Assign fa0/1 - 4 back to VLAN1.
ii) Turn on trunking on the ports connecting the 2950 and 3550's and
use 802.1Q trunking.

My response was;

i)

2950#conf t
2950(config)# interface range fa0/1 - 4
2950(config-if-range)# switchport access vlan 1
2950(config-if-range)# switchport mode trunk
2950(config-if-range)# switchport trunk encap dot1q

and then

3550A#conf t
3550A(config)# interface range fa0/1 - 2
3550A(config-if-range)# switchport mode trunk
3550A(config-if-range)# switchport trunk encap dot1q

and also

3550B#conf t
3550B(config)# interface range fa0/1 - 2
3550B(config-if-range)# switchport mode trunk
3550B(config-if-range)# switchport trunk encap dot1q

The lab, however, states that it should be;

2950#conf t
2950(config)# interface range fa0/1 - 4
2950(config-if-range)# switchport access vlan 1
2950(config-if-range)# switchport mode trunk
2950(config-if-range)# switchport nonegotiate

and then on both switches;

3550#conf t
3550(config)# interface range fa0/1 - 2
3550(config-if-range)# switchport mode trunk
3550(config-if-range)# switchport nonegotiate
3550(config-if-range)# switchport trunk encap dot1q

Which is correct, or is this just two ways of doing the same thing?

Thx

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Comments

EdTheLad

Your config is the same apart from you left the dynamic trunking protocol enabled.Since you have manually set the ports as trunk you should have disabled the dtp, it is not manditory but best practise.

Dilan77

Thanks...

Just one other question, also related to the same sim (one of the switches in my home lab is currently down, hence the reason for using Boson CCNP).

Completely different scenario.

One 2950 switch connected to a 3550 switch, there is alink each on fa0/1 and fa0/2 connecting to the corresponding fa0/1 and fa0/2 port on the other switch.

The sh interface fa0/1 switchport command gives this display for all 4 ports (but using fa0/1 as an example)

Name: Fa0/1
Switchport: Enabled
Administrative mode: trunk
Operational mode: trunk
Administrative Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (1)
Trunking Native Mode VLAN: 1 (default)
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001

Protected: false

Voice vlan: none (Inactive)
Appliance trust: none

Here is the relevant entry in the running config (applicable for all ports)

interface FastEthernet0/1
switchport mode trunk
switchport access vlan 1
switchport trunk encapsulation dot1q

There is a device on the 2950 connected to fa0/5 which is on vlan 11.

Both the 2950 and 3550 have an interface on vlan 11.

Unless the ports connecting the two switches are set in vlan 11, the device cannot ping the vlan 11 interface on the 3550..the config for all four ports has to be

interface FastEthernet0/1
switchport mode trunk
switchport access vlan 11
switchport trunk encapsulation dot1q

corresponding result from sh inter fa0/1 switchport;

Name: Fa0/1
Switchport: Enabled
Administrative mode: trunk
Operational mode: trunk
Administrative Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 11 (11)
Trunking Native Mode VLAN: 1 (default)
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001

Protected: false

Voice vlan: none (Inactive)
Appliance trust: none

I was under the impression that if a port was set to trunking, it was irrelevant what access mode vlan it was in? So why do the ports have to be set to vlan 11 to allow the pings?

Humper

Good question, I would like to know the answer of this as well. I believe it may have something to do with the management vlan?

EdTheLad

The reason is due to your simulator

, in trunking mode it will work, the sim has an output that says trunk but its working in access mode.The access mode vlan 11 wil only be used when the switch port is modified from trunk to access mode.

Humper

omg thank god, I kept thinking that there was nothing wrong with what was trying to be done, but never figured the simulator was trash.

mikej412

ModemHumper wrote:

but never figured the simulator was trash.

What? You missed all my old posts?

Back in the Boson 5.x days -- one common solution to problems was to save your config, close out, and then run NetSim and load the config. You'd also have to manually reconfigure the hosts, since those would always get lost.

The other fix was just to keep trying -- after 3 or times where it didn't work, when it should -- if you kept trying, it would then magically work.

The flip side -- at times pings would work that shouldn't. Those usually took the save/restart option to "fix."

Dilan77 -- I'd be curious to know, is this the latest/greatest patched updated bug-fixed CCNP version?

Dilan77

Thanks Ed...

Yup...this is the latest & greatest fully patched Boson for CCNP v6

I do have home lab, however I can't get access to use 3550 switches and the ones on ebay are too expensive, so bought the simulator to practice commands on those.

I've only been using it for the BCMSN so far and have to say the quality is *extremely* poor. Almost every lab has a serious error, the Spanning Tree lab does not work at all (e.g. either no output for show spanning-tree commands, or very bizarre ones) and the lab instructions have a lot to be desired...for instance on this lab, it actually states to "assign both ports that connect the 2950 to the 3550 as trunking ports in VLAN 11".

Another lab involves giving two switches identical IP addresses. Interfaces are down when they shouldn't be, pings randomly work or don't, VTP doesn't work properly and so on. I've logged a support case each time, but hear the standard response of "we have duplicated the issue and will be releasing an update shortly" which has gone on for months.

Basically, it is a pile of pooh.

Can't wait to get my replacement 2950!