IT Support, Sr. Analyst/Programmer

[jsciscovpn]

I'm not able to configure two ports on a C2950 as trunk ports, in order to connect to another similar switch.

I did what's recommended:

en

conf t

int range fa0/23 - 24

switchport mode trunk

end

Keeping the default encapsulation (802.1q)

The ports still show in the default vlan 1 and there's nothing in: sh int trunk

What am I missing?

Jerry

[jsciscovpn]

Hi Jon,

So my sw1 has a bunch of stuff on it: (I've attached the running config)

fa0/19 - 20 already has an channel-group 1 (they go to another sw for phone)

The existing connections (p21-p22 & p23-p24) on it to sw2 and to sw3 are however NOT setup as etherchannel but rather as trunk with crossed patches

I'm trying to setup ports 17 - 18 to connect to the new sw4. This morning they connected with the crossed patches but now I'm trying to create the etherchannel

My  question would be, should I be creating another one for p17 - 18, then another one for p21-22, and for p23-24 ? or can I use the same channel-group1 that's used for p19-20

Jerry

[Jon Marshall · Accepted solution]

You need to use a separate etherchannel per connection so for each set of two links you need a new etherchannel with a different number.

The number you use corresponds to the port channel interface so you enter the interface range and then add the "channel-group <num> mode ..." command and it will automatically create a "po<num>" interface in your configuration.

See the configuration guide for full details but just to say you do not create the port channel interface yourself.

You do not need to match both ends of the etherchannel in terms of number you use although if you can it helps with administration.

Once the port channel is created for you then you add any other commands you need only to the port channel interface and they are replicated to the individual ports within the etherchannel.

Hope that has cleared it up, if not please feel free to ask further.

Jon

[jsciscovpn]

worked like a charm! Thanks for the clear and thorough explanation, now I get it!!

Jerry

[Jon Marshall]

No problem, glad you got it working.

Jon

[jsciscovpn]

Funny though, now that the new sw4 is behind sw1 via etherchannel trunk, and devices on it connect, I'm not able to telnet into it. As soon as I start typing the password it looses connection, also can't get in via browser.

It only works if  I remove it and connect directly. any ideas?

[Jon Marshall]

Is connectivity working for clients connected to the switch ?

What is the IP address of your client ?

Which switch is your client connected to and how is that switch connected to sw4 ie. are there any other switches in between ?

Can you post the configuration of sw4 and also the output of a "sh int trunk" ?

Jon

[jsciscovpn]

yes, clients on sw4 work fine, vice versa.

client on sw4: 192.168.1.239

no matter which sw we come in from, once we telnet sw4 (192.168.1.244) we get the password  prompt, as soon a key is entered , the connection drops. Even browser login fails

I'm sorry, sw4 is back on connection with sw1 so I can't get in to give you the sh int stunk

[Jon Marshall]

I'm assuming you are connecting from a device with an IP of 192.168.1.x ?

The only other thing is on sw4 under the port channel interface can you add -

"switchport mode trunk"

as this should be there because the port channel does not inherit the physical port configurations, only the other way round.

Jon

[jsciscovpn]

yes, everyone in the network is in that range

added the switchport in Po4

still can't login to sw4 once connected to sw1

here's the latest sw4 config. btw: sh int trunk shows blank on sw4 while in stand-alone mode. Can't get in while connected to sw1

We'll have to continue in a week...Thanks,

Jerry

[Jon Marshall]

Okay, just repost back into this thread when you want to look at it again.

Can't see anything obviously wrong with the configuration and at least the clients are working so it is more of an administration issue.

Jon