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New Member

Connectivity between two 2960 switches

     I have a 3com that I am replacing with a 2960 switch. The 3com is connected to an existing 2960 that will still be there using a cross over cable. I want to connect the new 2960 and old 2960 and take out the 3com. My router is connected to the 3com so the new switch will take that connection. When i put the new switch in place of the 3com I can do anything on my network and internet. the problem I am having I cant even ping the old switch from the newe or even directly connected to it but I can putty to it. I tried different port but still can ping the ip of the old switch even though i am directly connected to it. I can connect to devices that is connected to the old switch that I cant ping.  it seems that i can go in but the ports are not responding on the old switch.

 

Router is connected to port 1 and port 25 on the 3com so I am using the same on the new whcih is ss_art-switch2960-2

 

Port 48 on the new is where I am making the connection the to old 2960 G1 port using a cross over.

 

'

40-2960-48.124 - is the old switch

ss-atr-switch2960_2 - new switch that is replacing old 3com.

 

I am attaching the config of both. Please any help!

10 REPLIES
Cisco Employee

Connectivity between two 2960 switches

Hi Robin,

R1(2950)---Vlan 1 ip 172.16.40.123-------------------------------Vlan 2 ip 172.16.40.124 R2(2950)

This is straight forward decision it should work without any issue.

Just tested on my lab it works fine.

couple of things to check here:

1- Did you try changing the cable connected between these two switches?( If possible try different port and dont configure anything on that port.

2- Whats the status of the port?

3- Do both the switches see themself under show cdp negihbor cmd?

4- Last but least we can check by debug icmp to see what is causing it not to ping.

HTH

Regards

Inayath.

Connectivity between two 2960 switches

Robin,

The issue is in your new switch config.

Currently you have the following on the Uplink port (trunk) going towards old 2960 switch:

interface FastEthernet0/48

description 2960 downstream

switchport trunk allowed vlan 2

switchport mode trunk

Remove the command "switchport trunk allowed vlan 2" and add "switchport trunk allowed all"

Only then you'll be able to communicate over Vlan1 which is also acting as your management vlan.

Hope it helps.

Neeraj

New Member

Connectivity between two 2960 switches

Neeraj there is not a "switchport trunk allowed all". There is no "all" but I can specify a vlan. Should I leave Vlan 2 and add Vlan 1 ie "switchport trunk allowed vlan1" and not removing vlan2?

Highlighted

Re: Connectivity between two 2960 switches

My bad, the command is "switchport trunk allowed vlan all" to allow all the vlans to pass through the trunk port

If you do not wanna do that and want to restrict others while allowing vlan 1 & 2, then use the command "switchport trunk allowed vlan add 1"

Re: Connectivity between two 2960 switches

Hello Robin

First of all both these switches are running as host switches mean no inter vlan routing is configured
and with 3 vlans on switch 40-2960-48.124 I assume if any, the  inter-vlan routing is being done on the router?

Also on switch SS_ATR_Switch2960_2 Port 1 and 25 are configured differently even though they
are connected to the same router with the native vlan on port 1 different to port 25?

If yout router is not performing inter-vlan routing then these switch interfaces dont require to be trunked and can be configured as access ports, but if it is then configured both switch interfaces the same.


On the interfaces between the two switches i would change it to be the same interms of defining
the encapsulation ( if applicable)  and trunk mode and use the  (if possible) the GigabitEthernet ports
and at this time allow all vlan to cross the trunk.

Try this:

Both switches on all access ports

switchport host

40-2960-48.124

conf t
interface GigabitEthernet0/1
swtichport trunk encap dot1q
switchport mode trunk

SS_ATR_Switch2960_2

conf t

default interface FastEthernet0/48


interface GigabitEthernet0/1
description 2960 downstream
swtichport trunk encap dot1q
switchport mode trunk

After these changes can you post some show commands:

sh int trunk
sh vtp status
sh vlan brief
sh int gig0/1 switchport

Please don't forget to rate any posts that have been helpful.

Thanks.

Please don't forget to rate any posts that have been helpful. Thanks.
New Member

Connectivity between two 2960 switches

I haven't done your recommended changes. I will do after hours. How can I tell if routers is intervlan?

The reason why you are seeing configuration on port 1 and 25 is i have a WAN optimization unit between the switch and router. The way that configuration is done is there are four ports on the wan opt device (Wan0, wan1, lan0 and lan1). wan0 goes to fe0/0, wan1 goes to fe0/1.    Lan 1 goes to port 25 and lan 0 goes to port 1. Even without the WAN device between the router and switch I cannot ping anyting on 40-2960-48.24 when i connect to a port on the 40-2960-48.124 but can get to a server that is already connected to a port on 40-2960-48.124 and i am coming in from ss-atr-switch2960-2.

I will try your config tonight.

Connectivity between two 2960 switches

Uplinks Connected To Both Switches

Do

default Interface FastEthernet0/48

interface fastethernet 0/48

Switchport mode trunk

switichport trunk allowed vlan all

Jawad

Re: Connectivity between two 2960 switches

Hello

Your two switches have a default-gateway - I assume this is of the router- so any communication between vlans will need to be done on this router.

Does your rotuer have sub-interfaces for the differeant vlans specifed in your switch config, If so then it is setup of the inter-vlan routing.

res

Paul

Please don't forget to rate any posts that have been helpful.

Thanks.

Please don't forget to rate any posts that have been helpful. Thanks.
New Member

Connectivity between two 2960 switches

Hello pdriver, I addd my router config. If I pan to use G1 on both switch like you recommended does your config still holds tru. All I am wanting to do is allow everyone to access all vlan on both switches. I will try everyone config later tonight.

Thanks everyone for all your help. I am still new to this cisco.

Cisco Employee

Connectivity between two 2960 switches

Hi Robin,

Dont worry we are here to help you. In regards to this make sure you check first the basic issue start your troubleshooting from layer 1 and go upto the network.

1- Check physical cabling

2- Check and make sure the ports connecting between the switches/routers are trunk port and all the vlans are allowed.

3- Check if there has to be any intervlan routing to be able to communicate between each other if those vlans are on different networks.

4- Check the switchport parameters to see if by any chance the STP is blocking the vlans not to forward on that particular links.( cmd to check the same eg: : Cisco# show int g1/0 switchport---Make sure the vlans are in forwarding state and not pruned).

5- Check if there is any port security or VTP pruning been configured.

Please feel free to get back to us if you face any issue after looking all the parameters.

HTH

Regards

Inayath

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