IronPort Systems 4108GL - Manual (Page 420)

18-8
Troubleshooting
Unusual Network Activity
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One or more CDP neighbors appear intermittently or not at all in the
switch’s CDP Neighbors table.
This may be caused by more than 60 neigh-
boring devices sending CDP packets to the switch. Exceeding the 60-neighbor
limit can occur, for example, where multiple neighbors are connected to the
switch through non-CDP devices such as many hubs.
The Same CDP Switch or Router Appears on More Than One Port in
the CDP Neighbors Table.
Where CDP is running, a switch or router that is
the STP root transmits outbound CDP packets over all links, including redun-
dant links that STP may be blocking in non-root devices. In this case, the non-
root device shows an entry in its CDP Neighbors table for every port on which
it receives a CDP packet from the root device. See “Effect of Spanning Tree
(STP) On CDP Packet Transmission” on page 12-23.
IGMP-Related Problems
IP Multicast (IGMP) Traffic That Is Directed By IGMP Does Not Reach
IGMP Hosts or a Multicast Router Connected to a Port.
IGMP must
be enabled on the switch and the affected port must be configured for “Auto”
or “Forward” operation.
IP Multicast Traffic Floods Out All Ports; IGMP Does Not Appear To
Filter Traffic.
The IGMP feature does not operate if the switch or VLAN does
not have an IP address configured manually or obtained through DHCP/Bootp.
To verify whether an IP address is configured for the switch or VLAN, do either
of the following:
■ Try Using the Web Browser Interface: If you can access the web
browser interface, then an IP address is configured.
■ Try To Telnet to the Switch Console: If you can Telnet to the switch,
then an IP address is configured.
■ Using the Switch Console Interface: From the Main Menu, check the
Management Address Information screen by clicking on
1. Status and Counters
2. Switch Management Address Information