> Hello -
> thnaks for the responses. As a work around,To have a router enabled
> for tagging, does that mean that the Router will give out two
> different MAC Addresses on the UT PPorts to avoid the loop ?
Enabling tagging on the switch will not (or at least should not)
automatically change the behavior of the router to use different
MAC addresses. So along with enabling tagging on the router,
you would have to Connect the router to the switch using only one
port that is configured as tagged and is in both VLANs.
> Another option I want to try , is to disable MAC learning on L2
> switch.To do this the MAC learning table is filled up with dummy
> entries, so that when a packet comes in , as MAC Table is filled up
> the L2 switch forwards the packet based on the VLAN filters on the L2
> switch. My current VLAN confg is
> Port 7 and Port 2 are in 1 VLAN group, and Port 8 and Port 1.So when
> packet comes in for Port 7 , and if MAC table is filled up, it
> forwards to Port 2 anyway.
> Now the question is filling up MAC tTable, will it cause any other
> that no new addresses will be learnt.
This is an interesting proposal. If you needed more than 2 ports
in any VLAN, then it wouldn't be efficient, but otherwise what
you suggest should actually work. Also, there might actually be an
option to disable addresses learning on the switch (this would
be most efficient, since it wouldn't bother to send frames for
With your proposed configuration, every frame would be treated as one
with an unknown SA and an unknown DA, and would be sent for learning and
to be broadcast (on the VLAN). Depending on the architecture and
implementation, they may very well be a performance impact. It's
hard to say how much its performance would degrade, though. I think
you'd just have to test it and see what it does.
> your comments on this is welcomes
> > If the router is using the same MAC address on its interfaces
> > into both subnets, then you would need to use the independent VLAN
> > learning (IVL) mode of operation. If you use the shared VLAN
> > learning (SVL) mode, then the address can get learnt only in one
> > port, regardless of which VLAN it was learnt on. In the IVL case,
> > it is possible for the switch to learn the same address on different
> > ports depending on VLAN.
> > If your switch does not support IVL, one possibility is to
> > have only a single tagged port go the router and make sure that
> > the router is enabled for tagging. (That assumes that the
> > router is able to perform/understand tagged frames.)
> > -Anoop
> > > Hello -
> > > I have a setup as follows
> > > 1. PC1 is connected to L2Switch Port 7, and PC2 is connected to L2
> > > Switch Port 8.
> > > 2. Port1 and Port 2 of the L2 switch connect to Router Interface
> > > upstream.
> > > 3.PC1 is on 192.168.1.208 IP address and PC2 is on 184.108.40.206. The
> > > Router Interface is configure for these to route between these.
> > > 4. Port 7 and Port 2 are in one Port based VLAN on the L2 switch
> > > 5.Port 8 and Port 1 are in another Port based VLAN on the L2 switch.
> > > 6. Both the ports on the Router give the same MAC addresses to Port 1
> > > and Port 2
> > > of the L2 switch.(virtual MACs)
> > > When I ping Pc2 from PC1, and ping PC1 from PC2,only one way ping
> > > works (ie. no request timeout).
> > > My intial observation on the ARL Table on L2 switch showed that as the
> > > Router was giving same MAC addresses on Port 1 and Port 2 ,only one
> > > entry is present in the ARL Table. Hence the flapping of the Pings .
> > > Is this the expceted begaviour, or is there any work around to this ?
> > > Any comments /observations ont this would be welcome
> > > Thanks
> > > Kott