From: Chuck Church (cchurch@xxxxxxxxxxxx)
Date: Mon Apr 29 2002 - 20:35:32 GMT-3
David,
802.1Q doesn't tag VLAN 1 frames. If you want to access VLAN 1 from
the router, apply the layer 3 addresses to the physical interface. Although
I've been told by a Cisco insider that this isn't recommended. I can't
remember the reason though. I think you're better off just not using VLAN
1. At least in a production environment.
Chuck Church
CCIE #8776, MCNE, MCSE
Sr. Network Engineer
Magnacom Technologies
140 N. Rt. 303
Valley Cottage, NY 10989
845-267-4000
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
David
Sent: Monday, April 29, 2002 4:07 PM
To: ccielab@groupstudy.com
Subject: Dot1Q trunk vs ISL trunk
In the test lab, Ive 2 VLANs (Vlan 1 & 2) on catalyst
2912XL setup, with dot1Q trunks to a Cisco router. The
router has 2 subinterfaces corresponding to the vlans
(see config below). There is a token ring at the other
end of the router. The problem is that with dot1Q the
hosts on t ring cant talk to hosts on VLAN1 on the
cat. But if I replace the dot1 with ISL trunk then it
works fine.
Im being told that with dot1q I need an extra vlan to
make it work. Any ideas why? & what config changes are
needed.
Thanks a lot
version 12.0
!
hostname cat
!
interface FastEthernet0/1
switchport mode trunk
switchport trunk encapsulation dot1q
!
<deleted>
!
interface FastEthernet0/11
switchport mode trunk
switchport trunk encapsulation dot1q
spanning-tree portfast
!
interface FastEthernet0/12
switchport mode trunk
switchport trunk encapsulation dot1q
!
interface VLAN1
ip address 192.168.1.1 255.255.255.0
!
line con 0
transport input none
stopbits 1
line vty 0 4
login
!
end
hostname R1
!
interface FastEthernet0/0
no ip address
duplex auto
speed auto
!
interface FastEthernet0/0.1
description Local LAN interface
encapsulation dot1Q 1 native
ip address 192.168.1.100 255.255.255.0
no ip redirects
!
interface FastEthernet0/0.2
encapsulation dot1Q 2
ip address 192.168.2.100 255.255.255.0
no ip redirects
!
interface tokenring0/0
ip address 172.16.1.100 255.255.0.0
!
router ospf 1
network 0.0.0.0 255.255.255.255 area 0
!
line con 0
line aux 0
line vty 0 4
login
!
end
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