Please share how to check for heavy broadcast on L-2(Vlans) network. i.e how to confirm that heavy braodcast is coming from which particular Vlan on L-2 network.
Additonally, If STP is not enabled and there is loop on the link. Is there any possibility that loop is there only due to particular Vlan i.e not just b'coz of physical scenrio.
1.) You can use a sniffer, like Ethereal or SnifferPro to examine and analyze the traffic being sent on the vlan. After the network stabilizes and the switches CAM tables are built and the end stations have their ARP tables populated, there really shouldn't be too much broadcast traffic. Typically, DHCP and ARP requests account for most broadcast traffic on an Ethernet segment.
2.) Loops exist because of the physical topology, period. If there arent any parallel data paths for a particular vlan (assuming you are deploying per-vlan STP), you cannot have a loop. Now, there are measures taken in software to mitigate those parallel paths, such as vlan pruning, and of course the STP algorithim itself.
For POint 1) Instead of third party tools, is there any cisco IoS command to check the heavy traffic from particular Vlan.
For Point 2) Conculded that loop only creates only due to physical topology. Not by any particular Vlan.
For Point (1) i suppose there is some mis-confusion now. I am not asking for how to check traffic on particular interface.
I am looking for, How to check that heavy traffic is generating from which particular vlan among the big L2 network.
All I can recommend is that you enable ip accounting on the vlan interface. It will give you the source and destination addresses of the flows going through that interface.
Or enable NetFlow monitoring.
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Point 1 - Ehterreal (AKA Wireshark) is a free tool (Google Wireshark) that any network professional should have and know how to use. It is relatively easy to set up and use. This is the best option for tracking traffic. Sniffer is good also, but $$$$.
Spanning Tree - Be very careful not running spanning tree on a multiple switch network. One mis-cable and your loop free topology is toast. My experience is the majority of network issues relate back to spanning tree or other layer 2 issue.
Your name sounds familiar...I did some work for Calence a few years back at TWC.
Anyway, he wants a Cisco tool, not Ethereal, etc. I suggested those first, too.
Thanks. accouting command is not supportin on cisco 4507 switch. I have also tryed on global config mode and also on Vlan int.
Cisco_4507(config)#int vlan 20
Interface IP configuration subcommands:
access-group Specify access control for packets
address Set the IP address of an interface
authentication authentication subcommands
Can there is any other solution. As i guess L2 & L3 switch will not support this commands. I want this utility for tracking broadcast from Vlan(L2) network.
Victor and Bruce have both given you the answer:
Use Wireshark! (Previously called Ethereal)
It is open source (and therefore free).
It's what it is for, and any networking pro worth their salt should know how to use it.
Just install it on a laptop and connect it to vlan 2.
-Click Capture -> Options
-Choose the interface to listen on at the top.
-In the capture filter put: "ip and broadcast"
-Change the Display options as desired.
If you want to see ethernet broadcasts as well as IP broadcasts, change the capture filter to just "broadcast"
Thanks a ton..!!!
Surely will implement and try this. But must to mention that preferably i am looking for tool or utility from cisco only to fulfill this requirement.