MPLS, Routing, and switch question.

[ddevecka]

I am having issues with a 2921 router and a 2950 switch. Here is what I am doing. I have a 2921/CME router connected to a 2950 switch and that is connected to our MPLS cloud. I can get to the router from our remote location but can’t get to anything else on the network. I can ping the router get into it remotely but can’t get past the Ethernet interface on that router. We do have Vlans configured on the router for a VoIP install that we will doing next year. I have cleared the config on the switch and still nothing. Below is the config for the ports that are connected. This is the config on the router port: interface GigabitEthernet0/1 no ip address duplex auto speed auto ! interface GigabitEthernet0/1.18 description Data Network encapsulation dot1Q 18 ip address 1.2.3.4 255.255.0.0 ! interface GigabitEthernet0/1.19 description Voice Network encapsulation dot1Q 19 ip address 1.2.3.5 255.255.0.0 Here is the 2950 switch port config. interface FastEthernet0/12 switchport access vlan 18 switchport mode trunk no ip address duplex full speed 100 Not sure what I am missing here. Any help would be appreciated.

[Richard Burts]

There is not much information here to work with. But here are a couple of guesses about what the issue might be.

- you say that you have cleared the config on the switch. Is it possible that one or both VLANs are not correctly configured?

- if you can ping the router then obviously you have basic IP connectivity to that interface (you have a route to it and it has a route to you). If you can not ping other interfaces, then one possibility is that you do not have a route to those interfaces. Do you have a route to the subnets of the other interfaces? One way to check is to try a traceroute (or tracert depending on OS you are using). Does the traceroute show that you are taking the correct path to the router?

- is it possible that you need to do address translation of the traffic (or that you need to exempt the traffic from address translation)?

HTH

Rick

[cadet alain]

Hi,

This is the config on the router port:
 interface GigabitEthernet0/1
 no ip address
 duplex auto 
speed auto 

interface GigabitEthernet0/1.18 
description Data Network
 encapsulation dot1Q 18 
ip address 1.2.3.4 255.255.0.0 

 interface GigabitEthernet0/1.19
 description Voice Network 
encapsulation dot1Q 19
 ip address 1.2.3.5 255.255.0.0 


Here is the 2950 switch port config:
 interface FastEthernet0/12 
  switchport access vlan 18 
  switchport mode trunk
  no ip address
  duplex full 
  speed 100

I put your "config" in a more readable form ( hope you won't mind me doing this ).

Anyway,

1) you are putting the same subnet on both subinterfaces - A VLAN = a subnet

2) I suppose VLAN 18 is data vlan and so is untagged or native but you don't specify in your config

   so by default the native vlan is on the physical interface.

3) a port can't be a trunk and an access port at the same time  and so your first command under f0/12 is not necessary but that is not the cause of the problem.

Now what do you want to ping that is not successful? Is this the switch but if so have you got a default gateway as well as a SVI configured on it?

Are these hosts in your LAN? have they got their default gateway as ip address of subinterface in their same subnet?

Regards.

Alain.

[ddevecka]

Again this is the config on the router interface plugged in to the switch on port 12

interface GigabitEthernet0/1

no ip address

duplex auto

speed auto

!

interfaceGigabitEthernet0/1.18

description Data Network

encapsulation dot1Q 18

ip address 172.18.0.1 255.255.0.0

!

interface GigabitEthernet0/1.19

description Voice Network

encapsulation dot1Q 19

ip address 172.19.0.1 255.255.0.0

Here is the config from the switch on port 12 that is connect to the router.

interface Fastethernet0/12

switchport mode trunk

no ip address

I have vlan18 configured on the switch and router. I have all the ports on the switch in vlan18. I am just try to be able to ping the router from the switch and the switch from the router. I assume it is something I had configured in the router that isn't allowing traffic to pass thru the router. Again basically the ethernet port on the router isn't respnding to pings and not allowing traffic to pass thru it.

[cadet alain]

Hi,

I am just try to be able to ping the router from the switch and the switch from the router

This switch is in your LAN and your router is a CE router for MPLS?

Then you need a interface vlan 18 on your switch.

Can you  do a debug ip packet   when pinging between switch and router where acl is an ACL only permitting icmp.

Regards.

Alain.

[ddevecka]

I a vlan 18 on my switch. Here is the complete switch config.

[ddevecka]

Also the router is under our control not the ISP. From our MPLS cloud I can get to the router via telnet. Anything on the other sie of the router I have to access via a webex or a go to my PC this is done via a seperate Internet connection.

[cadet alain]

Can you do the debug I asked you  while pinging and post the output.

Regards.

Alain.

[ddevecka]

Here is what I hope you wanted.

[Richard Burts · Accepted solution]

There are several things that I suggest that you check.

- can you verify that interface vlan 18 on the switch is up/up? The output of show ip interface brief is the best way to do this.

- can you verify that there is working connectivity between the switch and the router? the output of show cdp neighbor would be a good way to verify this.

- can you post the output of show mac-address-table from the switch and verify the MAC address of the router is in the table?

- after you attempt to ping the router interface can you post the output of show arp on the switch. This will show whether the router is responding to ARP?

HTH

Rick

[ddevecka]

I did the sh cdp ne and figure out that they told me the wrong port for the trunk port. Thanks to all for the help. Been a long time since I used the Sh cdp command. Thanks for all the help.

[cadet alain]

Hi,

from output we see that the icmp echo frame is sent untagged because you only have 14 bytes header( 114 - 100) but as you have it tagged on the router,

I think the router is not processing the frame and so you get no replies.

Can you do same thing(same ping from switch) but debugging on the router side this time to confirm he is not sending echo replies.

I would try to modify g0/1.18 config like this: encap dot1q 18 native.

Regards.

Alain.

[cadet alain]

Hi,

glad you worked it out.

Regards.

Alain.