STP-Switch can't communicate with each other

[smartd1011]

I added a STP lab (3 L3 switches)  into my exiting Route Redistribution network lab. I assigned trunk ports to appropriate  Gig. port to create trunk link between switches. I also issued command: spanning-tree vlan 10(20)  to each trunk port. I added a laptop to SW3 and assigned ip address(I don't have default gateway address, so used lo0 5.5.5.5 instead. I think I'm wrong ).

Now, I can't ping from one switch to another(except SW1 to SW2 through R1 and R2). I also can't ping from laptop to any switch or Vise Versa. I tried to debug for a couple of hr. but no luck. 

I attached the topology and config. file. 

I hope someone can help me find a clue.

Thank you!

[e.ciollaro]

Hi,

it seems me that you can't ping between Sw1 and Sw2 because interface are on different subnet and you have not ip routing protocols between switches. So Sw1 has no path to subnet 4.4.4.0/24 or 30.0.0.0/24 other then through R1 and R2. Isn't it ? 

Enrico

please rate if useful

[smartd1011]

Thank you for the reply. 

My purpose is use trunk link to direct connect 3 switches. in other word, I want to set 3 switches themselves as a layer 2 network. So, I don't need config routing protocol right. I did assigned the ip addresses for the switches interfaces(not G1 to router) by accident, but I changed them into trunk port by using the command: switchport. I did realized one thing: after the change , I highlighted on each switch in the topology, the ip adddresses still show next to the interface. Maybe they still work as L3 interface but not the trunk port and that is the cause? do you know how to get rid of the ip addresses. I used command: no ip address but doesn't work.  I did set SW1 & SW2 as L3 switch by enabled ip routing(not SW3). The purpose is to connect them to the routers by using routing protocols. 

BTW, you mentioned about the switch's interfaces is on different subnet. But, EIGRP and RIP already take care of it. My concern is the connectivity for the lower half of the topology. There is no direct link connectivity between switches. I also changed ip for the laptop to 12.0.0.8 but won't help neither. I just set SW1 as root switch and hope that do the trick but not. I don't know what to do now. I think I'm missing something in the switch config but just don't know what it is :(

[Jon Marshall]

It is nothing to do with STP because there is no loop.

The links between the switches are trunks.

But from your above description it's not clear what the links from SW1 and SW2 to the routers are ?

Also do you want all the switches to be just L2 ?

If you want your switches to be just L2 then you don't want or need loopbacks on the switches.

So we need clarification really before we can tell you what you need to change.

Jon

[smartd1011]

Hi Jon,

    Thank you for the help again!

     I'm trying to nest SW1 and SW2 with both L2 and L3 config. SW1's G0/1 is routed port and G0/2 is trunk port. SW2's G0/1 is also routed, and G0/2 is also trunked. The link from SW1 to R1 is via EIGRP, SW2 to R2 is via RIP2. The link between SW1,2 and 3 are trunk. 

Today,I added vlan 20 to SW2 & SW3 and also added another PC to SW2. I assigned ip to laptop and PC2 in the same subnet, then I'm be able to ping between PC1, PC2 and laptop. 

But, after I added this config. 2 weird thing happened:

I was be able to ping from any switch to any workstations, but after a few minutes, I can't ping from SW1 to laptop and PC2. I also can't ping from SW2 to laptop and PC1. But, I can ping from SW3 to them. If something wrong with SW1&2, then how can I ping between PC1,2 & laptop. 

I also can't ping from PC1 to SW2's G0/1 30.0.0.2 anymore. can you help me with that?

[Jon Marshall]

You must have done something to SW3 as well to be able to ping from it because in your original configuration it only has a loopback and it shouldn't be able to ping anything.

Can you just confirm -

1) on both PCs and the laptop you have the default gateway up ?

2) for the PCs and the laptop you have allocated the ports into the correct vlan on the switches they are connected to ?

Jon

[smartd1011]

Yes, I did assign default gateway address for them. I also assigned one port of each switch to vlan 20 and I connect all 3 end devices to those port. 

I don't have default gateway address for PC2 and laptop, So I used loopback address. Should I used vlan 20's gateway ip address 12.0.0.1 for them instead?

[Jon Marshall]

I have just looked at your screenshots.

You cannot use the same IP (12.0.0.1) on all three switches.

You need each switch to have a different IP from that subnet ie. only one of the switches can use the above IP.

The PCs and laptops, if you assign them into vlan 20 then use the above IP as the default gateway.

You do not necessarily need all switches to have an IP in this subnet although SW3 probably should have.

Every device must have a unique IP address within a vlan and all devices in the same vlan will have the same default gateway.

Jon

[smartd1011]

Thank you for the tip Jon!

[e.ciollaro]

Well, If I have understood, your purpose  is to set up a L2 network between Sw 1, Sw2 and Sw, put laptop and PC on VLAN 20 and  ping between them without using R1 and R2. If so you have to create VLAN 20 on Sw1, Sw2 and Sw3 (VLAN 20 are not defined in Sw2 and Sw3), assign Sw1 f0/2   interf and Sw3 f0/1  to vlan 20 (interf config missing in your xlsx file) and assign Laptop and PC to the same ip subnet. This way they should ping each other.

[smartd1011]

you are right Enrico. I added vlan 20 to SW2 & SW3 and also added another PC to SW2.

I assigned ip to laptop and PC2 in the same subnet, then I'm be able to ping between PC1, PC2 and laptop. Thank you so much! 

But, after I added this config. 2 weird thing happened:

I was be able to ping from any switch to any workstations, but after a few minutes, I can't ping from SW1 to laptop and PC2. I also can't ping from SW2 to laptop and PC1. But, I can ping from SW3 to them. If something wrong with SW1&2, then how can I ping between PC1,2 & laptop. 

I also can't ping from PC1 to SW2's G0/1 30.0.0.2 anymore. can you help me with that?

[e.ciollaro]

The first thing I noticed is that your WS2 and WS3 are configured with a default gateway that is on a different subnet then their subnet (Ex WS2 is 12.0.0.10 and it's def. gateway is 4.4.4.4). You should use the SVI of Sw2 and Sw3 instead of loopback interf.

In any case WS doesn't need the default gateway to ping host on their subnet. I don't understand whta is happening and I agree with Jon: Sw3 has no interf on subnet 12.0.0.0/24 so I can't figure out how it can ping  on that subnet. Please try to make a sh ip interf brief on Sw3, just to see if there is an interf on that subnet and/or post a txt with Switch 1,2 and 3 running-config

[smartd1011]

Yes, I did use  SW2 & SW3's loopback address as default gateway for the laptop and WS2. So you mean use SVI(vlan 20's ip 12.0.0.1 as DG address for SW2&3? Since you said I don't need them if hosts are in the same subnet, so I can just leave it blank in the host config. oh, If want to ping from server to laptop, then I still need it for SW3 right?

I attached screenshoots of 3 SW.'s interfaces detail. I did misconfig the ip addresses for SW1 G0/2, SW2 G0/2  and SW3 G0/1& G0/2. I changed those ports to trunk  but ip addresses still shows there. I can't took them off. Do you know how? 

Regardless for all of these, what is reason that I can ping from WS1 to SW2's G0/1 port by go through R1  and R2?

[e.ciollaro]

I can just leave it blank in the host config. oh, If want to ping from server to laptop, then I still need it for SW3 right?

You need a default gateway configured on IP hosts, every time you need to ping (or send any ip traffic) outside their ip subnet (really you can also config proxy arp on routers but forget it by now). 

I changed those ports to trunk  but ip addresses still shows there. I can't took them off. Do you know how? 

Did you config "no switchport" ? 

Regardless for all of these, what is reason that I can ping from WS1 to SW2's G0/1 port by go through R1  and R2?

The scenario is not very clear to me, if WS1 is the PC connected to f0/2 port of Sw1,  probably is due to the fact that:

 - Sw2 is part of OSPF area  and

-  router 1 is redistributing form OSPF to EIGRP (I guess)

 - if Sw1 has EIGRP still active (in first config you post, it was), then Sw1 receive OSPF routes and therefore has a path to Sw2 G0/1.

Bye,

enrico

[smartd1011]

I think I did config no switchport on all switches' Gig. ports. Then, I changed

SW1's G0/2, SW3's G0/1 & G0/2 and SW2's G0/2 port into trunk port by the following comand:

switchport trunk encapsulation dot1q

switchport mode trunk

I am be able to ping from WS1 to SW2's G0/1 ports now without any changes.