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PT: Span tree after changing vlan priorities, no visible effect on sw

keesepema
Level 1
Level 1

Last week I offered my students a test in PacketTracer.

Part of the assessment was a topology with three 2960 L2 switches, where S2 was configured as VTP server, distributing vlan 10,20,30 and 40. S1 and S3 configured as VTP client.

Links between the switches had to be trunks allowing vlan 10,20,30 and 40. Students had to disable DTP negotation and change the native vlan to 99.

In the topology below, the root-bridge is choosen based on mac-address, because all bandwidths between the switches are equal.

span.png

So far so good.

The problem arose when the students had to  change the S1 priority for all vlan's to 4096.

 

 

S1(config)# span vlan 10,20.,30,40 prio 4096

 

 

The orange blinking led on the g0/2 interface of S1 disappeared, and did not re-appear on any other interface. Even when Fast forwarding time. All green blinking lights...

When I looked into the spanning-tree configuration of the switches I noticed that S3 had become the ALT port:

 

 

S1# sh span 

 

 

This VLAN 20 on S3 for instance:

 

 

VLAN0020
  Spanning tree enabled protocol ieee
  Root ID    Priority    4116
             Address     00E0.B0E5.7EBE
             Cost        4
             Port        25(GigabitEthernet0/1)
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32788  (priority 32768 sys-id-ext 20)
             Address     0060.704D.1A00
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  20

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi0/1            Root FWD 4         128.25   P2p
Gi0/2            Altn BLK 4         128.26   P2p

 

 

 My conclusion is that the LED's on the switches in PT reflect only the status of VLAN 1 and not other VLAN's. Am I right?

1 Accepted Solution

Accepted Solutions

Martin L
VIP
VIP

Yes, I do think that as well;  PT orange link LED is indicator for VLAN 1 status only;  if u have many vlans and change their Bridge priority; do not worry about link LED indicator (color)  

Regards, ML
**Please Rate All Helpful Responses **

View solution in original post

5 Replies 5

Trunk have multi VLAN's some are FWD abd other are BLK  so it will not totally BLK and orange color anymore

It normal in Packet tracer 

MHM

So access link for use different vlan will noy light as grean ?

It not relate to vlan1 

Anyway 

That my opinion 

MHM

When I am using multiple VLAN's in spanning-tree, the link light will only become orange in PT when VLAN 1 is included. I have spanning tree only enabled on trunks. I disable spanning-tree with bpduguard and portfast on access ports. All ports on the switch that are connected to an end device are assigned to VLAN's different than VLAN 1.

So yes I think the LED color changing has to do with VLAN 1.

Access port that not use vlan1 is green or orange ?

It grean sure.

The light is depend on the stp status of vlan in trunk 

If the ALL vlan in trunk is fwd the light will be green 

If any one of vlan in trunk is BLK the light will be orange

MHM

Martin L
VIP
VIP

Yes, I do think that as well;  PT orange link LED is indicator for VLAN 1 status only;  if u have many vlans and change their Bridge priority; do not worry about link LED indicator (color)  

Regards, ML
**Please Rate All Helpful Responses **