From: asadovnikov (asadovnikov@comcast.net)
Date: Sun Jul 27 2003 - 13:05:12 GMT-3
Cisco switches will accept the taged frames on native VLAN without any issue
to my knowledge. Cisco switches will not transmit frames on native VLAN
taged, and this is what your issue may have been. There is a document on
CCO talking about it but I can not find it right now. If I have local copy
I will mail it to you.
Latest switches (i.e. 3550) with new enough software can tag frames on the
native VLAN (per switch setting). I would try this and see if it helps.
Best regards,
Alexei
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Kristof Ulrix
Sent: Sunday, July 27, 2003 8:22 AM
To: CCIE-lab
Subject: Dot1Q between Cisco en Linux - Problem
Goal: Connect 2 linux-boxes to 1 switch with dot1q trunking
switch = Cisco 2950 12.1(13)EA1
Linux = Suse 8.2
We have 3 vlans:
- vlan1: used to manage all IP-devices (10.0.0.0/24)
- vlan2: User set A (192.168.1.0/24)
- vlan3: User set B (192.168.2.0/24)
Linux1 Switch Linux2
Vlan1 10.0.0.1/24 10.0.0.200/24 10.0.0.2/24
Vlan2 192.168.1.1/24 n.a. 192.168.1.2/24
Vlan3 192.168.2.1/24 n.a. 192.168.2.2/24
Situation A: 2 Linux boxes with X-cable (no Cisco switch)
On each Linux 3 vlan-I/F
The Linux1 can ping all 3 ip-addresses on Linux2, and vica versa.
Situation B: Switch (2950) in between 2 linux-boxes
On each Linux 3 vlan-I/F
Switch config:
dot1q trunking
vlan1: native vlan (Switch has vlan1 I/F with 10.0.0.200/24)
vlan2 and 3: normal vlan's
Linux1 van ping the 2 user vlan I/F on linux2, not the management Vlan
Switch can't ping any Linux-box.
Situation C: Solution
Put the native vlan on the 2 trunks in vlan 10 (not 1,2 or 3)
Linux1 can ping all 3 ip-addresses on Linux2, and vica versa.
Linux1 and 2 can also ping the switch (10.0.0.200)
Explanation:
Native Vlan is the vlan in which the untaged packets are put.
In situation A, all packets are taged (with 1,2 or 3) no problem.
In situation B, the cisco switch gets taged packets with VlanID = native
Vlan
Assumption => these packets are dropped = no connectivity on vlan 1
In situation C, the cisco switch gets taged packets in Vlan 1,2 and 3,
different from native, no packet drop.
Can somebody confirm this assumption.
The dot1q standard tells us to put all untaged packets in the native
(definable on the trunk)
But I don't find anything about packets which are taged whith a VlanId which
is the same as the native.
I think these packets are dropped.
Kristof.
This archive was generated by hypermail 2.1.4 : Wed Aug 06 2003 - 06:52:54 GMT-3