I am very new to network engineering, I have read through the netgear user manual and find nothing about Global Flow Control (IEEE 802.3x) Mode. Is it different than the storm controls that I have the ability to change all or per interface?
Network Control – Flow Control vs. Storm Control
layer2switch
Related Solutions
So does storm-control unicast only measure the pps rate (or bps rate) of frames that are for destinations not in the CAM tables, or all destinations that aren't a broadcast or multicast address (so just the total number of unicast frames)?
I have to confess that I mistakenly trusted the Nexus doc below which said only unknown unicast is rate-limited; however, that's definitely wrong for Cisco IOS. The reality is (at least on IOS platforms) that unicast storm control affects all unicast traffic; the Cisco Nexus doc I quoted said it only affected traffic that was unknown unicast. I will endeavor to test on Nexus at a later date.
In an effort to atone for my mistake, I built a quick screencast of what happens when I:
- Configure a Cisco IOS switch with unicast storm-control to throttle at 1Mbps.
- Use
speedtest_cli.pyto start a unicast download from speedtest.net - Reconfigure the switch without unicast storm control
- Download from speedtest.net again...
Hit your refresh button to restart the screencast at the beginning
Bottom line
- Unicast storm-control affects all unicast traffic in Cisco IOS
- Unicast storm-control is applied on traffic inbound to the switchport
My Original quote from the Nexus docs, which I applied to the OP's Cisco 2960
Quoting the Nexus Storm Control Docs (emphasis mine):
"You can use the traffic storm control feature to prevent disruptions on Layer 2 ports by a broadcast, multicast, or unknown unicast traffic storm on physical interfaces. "
Storm control operates the same way across Cisco platforms; if the destination-mac-address is not in the CAM table, then then the switch must flood it out all ports in the Vlan (except the one it came in on). Suffient quantities of this kind of traffic would trigger your Unicast Storm Control thresholds.
Basics
When you tag a VLAN on a port, it will send out the traffic on that port with the VLAN tag, when the port receives traffic it looks for the tag and places the traffic into that VLAN. You can have multiple tagged VLANs on one port (sometimes called trunk).
When you send out a VLAN untagged on a port it will not add the VLAN tag to the packet and when receiving packets without a VLAN tag it will be placed into that VLAN (on Netgear and others you have to set PVID (Primary VLAN ID))
To your problem
I think you are not far away... - Router port connected to Switch1 should have IP within VLAN 2220. - DHCP Server should have different IP from different Subnet! - Router port Connected to Switch2 should have IP in Subnet of DHCP Server - You should define a DHCP Helper on Router port connected to Switch1 so DHCP Request get forwarded to DHCP Server. Hot to do that is described here: http://kb.netgear.com/app/answers/detail/a_id/21990/~/how-do-i-configure-a-dhcp-l3-relay-using-the-web-interface-on-my-managed-switch%3F
Hope this helps you a little bit further. If not, please post a more detailed network diagram with VLAN IDs and IPs.
Best Answer
Ethernet Flow Control is different than Storm Control.
Ethernet Flow Control was developed because traffic on a link may be generated faster than the receiver can handle it. The IEEE has several efforts for this in 802.1 and 802.3. Unfortunately, this really doesn't help with STP loops.
Storm Control is something which some switch vendors have implemented, and it is typically used to limit broadcast and multicast traffic to acceptable levels in order to mitigate STP loops. Cisco does have an implementation for unicast traffic, too.