Hello group,

I'm not quite sure whether this is the proper group to post to concerning
the above mentioned topic. We spent almost three days trying to get the
following setup to work:

3Com Switch 4400-24, VLAN "Default" with port 1 assigned, the other 23 ports
are untagged members of VLAN 2 "Internet". On this unit, the ports 19 and 20
are added to aggregated link 1 (AL1).
3Com Switch 3870-24, VLAN "Default" with port 1 assigned, the other 23 ports
are untagged members of VLAN 2 "Internet". Ports 2 and 3 of this unit are
assigned to AL1.

Either AL1 is connected with the other unit, providing a 400mbit/s trunk.
The purpose for this setup is to use either port 1 for management and
monitoring reasons (with lan-IPs RFC1918 being used), yet having the
remaining 23 ports (minus 2 each for the trunk) on each unit handling public
IP-addresses for multiple mail and webservers. Needless to say that the
VLANs are used to isolate the internal LAN from the internet traffic.

Now the problem we are currently dealing with:
On the 4400 the VLAN1/2 setup is working fine. The RFC1918 management
interface on port 1 is accessible, so are all nodes connected to the ports
assigned to VLAN 2. The troubles are located on the 3870. With no aggregated
links defined, we can access the management interface on port1 and, as
expected, no machine on the VLAN2-ports. Upon fiireing up the AL1 we do not
have any access to any node on VLAN2. Once we unplug the port 1 cable, the
trunk seems to work properly and nodes in VLAN2 respond to requests. Again,
whenever we plug in the port 1 cable attached to our RFC1918 address space,
access to the VLAN2 nodes is not possible anymore.

Has anyone of you guys experienced this issue before? I've searched the net
for any similar problem, yet to no avail.
Any help is greatly appreciated!

Cheers,
Mark