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Weird CatOS to IOS Trunk Problem – Cannot Ping

I was setting this very basic configuration up the other evening and could not get basic L3 connectivity up and running.


I have a ASR 1002 on one side and an Catalyst 6509 running Hybrid CATOS and IOS. The configuration is basically to connect two devices for routing using 802.1q vlans. Here is the configs, but I cannot ping between the devices.


interface GigabitEthernet0/0/2
no ip address
negotiation auto
interface GigabitEthernet0/0/2.700
encapsulation dot1Q 700
ip address
ip ospf network point-to-point

6509 – Switch

set vlan 700   3/3
clear trunk 3/3  1-699,701-1005,1025-4094
set trunk 3/3  on dot1q 700
set spantree portfast    3/3 enable trunk

6509 - MSFC

interface Vlan700
ip address
ip ospf network point-to-point

I could not see any issue, so to confirm try and establish if it was some trunking issue, I remove the trunk and used the main interface on the ASR1000 and access port to vlan on the 6509 and I could ping between the devices no problem.


Happy the L2 was now establish I decided to rebuild the configuration again and still had the same issues. Not sure why I tried the next step but I modified the configuration on the 6509 to be this:

I issued set vlan 1   3/3

6509 - Switch

#module 3 : 16-port 1000BaseX Ethernet
clear trunk 3/3  1-699,701-1005,1025-4094
set trunk 3/3  on dot1q 700
set spantree portfast    3/3 enable trunk

Now everything is working ok ?

It also works with: set vlan 10   3/3 just not with the same VLAN as the trunk is using ???


It is Working

So in this situation it seems I cannot have the switchport configured with the same vlan id as I want to trunk. I found this really weird since I had stripped all vlans off the trunk anyway? Hope this helps some one else. Not that I really needed the Vlan assigned, so no big deal in most cases (what was I thinking!!!).


Code Level:


Cisco IOS Software, IOS-XE Software (PPC_LINUX_IOSD-ADVENTERPRISEK9-M), Version 15.1(1)S1, RELEASE SOFTWARE (fc1)

6509 – Switch

WS-C6509 Software, Version NmpSW: 7.6(9)
Copyright (c) 1995-2004 by Cisco Systems
NMP S/W compiled on Aug 27 2004, 20:05:14

System Bootstrap Version: 7.1(1)
System Boot Image File is 'bootflash:cat6000-sup2k8.7-6-9.bin'

6509 – MFSC

ROM: System Bootstrap, Version 12.1(11r)E1, RELEASE SOFTWARE (fc1)



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