Operating instructions

60 Cisco Systems Intelligent Gigabit Ethernet Switch Module
Management Module first, then connect to the IGESM, but that you can actually point a Telnet
or browser session directly at the IP address of the IGESM and directly attach (via a path
through the Management Module) into the IGESM as you would any other Cisco switch.
Here is one of the more confusing aspects of using the Management Module to provide the
management path to the IGESM: The VLAN that is defined on the upstream switch’s port,
which is connected to the Management Module’s port, does not necessarily have to be the
same as the
interface VLAN on the IGESM for IGESM management traffic to flow over the
Management Module and reach the IGESM. (See Figure 5-41.)
This is because although a management VLAN interface is defined on the IGESM, this VLAN
will always be carried over the ports headed out to the Management Module (G0/15 and
g0/16) as the native VLAN on a trunk because g0/15 and g0/16 are hard-coded as 802.1Q
trunks and the management VLAN interface is always assigned to the native VLAN. Thus it
will be untagged and appear as such to the Management Module.
To the Management Module’s interface (ETH1) facing toward the IGESM, this appears to be a
simple access link and it does not matter what VLAN the IGESM calls it because it simply is
looking for untagged packets that are being carried over the native VLAN, which is what it
receives. It then passes these packets out the ETH0 interface toward the upstream switch.
Even though the connection would still work if you use different VLANs, this can be very
confusing and thus it is usually recommended that you define the same VLAN in both the
IGESM (interface vlan X) and on the upstream port on the switch connected to the
Management Module (switchport access vlan X).
Figure 5-41 Consideration of management path to IGESM via the Management Module
Management
Module
IGESM
Bay 1 - 4
MGMT “Interface VLAN Y”
G0/15
Simple physical
connection
ETH 0
ETH 1
Trunked - But IGESM
management packets are always
assigned to the Native VLAN
(untagged)
When using the MM interface
to manage the IGESM, these
VLANs may be different and
the connection still works
All packets
untagged
All IGESM source
and destination
packets untagged
CIGESM
uplinks
Upstream switch
“switchport access VLAN X”
Sw Bay - external
management
over all ports
disabled