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Flow Control – Pause Frames

. When an Ethernet device gets over loaded, flow control allows it to send PAUSE requests to the  devices sending it data to allow the over loaded condition to clear.  If flow control is not enabled and an over loaded condition occurs, the device will drop packets. Dropping packets is much more performance impacting than flow control. 802.3X flow … Continue reading

Force10 DCB Configuration – S4810 + MXL Sample / Example

. First, some background on DCB itself. DCB is an extension to Ethernet that enables the dedication of resources in the converged network. To ensure lossless delivery and latency-sensitive scheduling of storage, service traffic, and I/O convergence of LAN over a unified fabric, IEEE data centre bridging adds the following extensions to a classical Ethernet … Continue reading

Layer 2 Discards Troubleshooting – RX TX Discards

. The following list of questions/vectors can assist in troubleshooting Layer 2 discard issues. They have been of help to me in the past on more than one occasion. What Switches/Models? What firmware versions? Look at the subsequent firmwares’ release notes for any identified issues, resolved caveats etc. that match what you re experiencing. What … Continue reading

Switch Port auto shuts/ port shuts itself down – Troubleshooting

. Following is a list of vectors that may assist in troubleshooting issues where the port behavior look like it is shutting itself down. Cable/ Power Management. A link light does not guarantee that the cable is fully functional. The cable could have encountered physical stress that causes it to be functional at a marginal … Continue reading

Force10 S4810 VLT – Quick Configuration sample

. I have already given a non-technical synopsis on VLT in one of my previous posts here https://hasanmansur.com/2012/10/15/force10-s4810-stacking-vs-vlt/ As mentioned, VLT Is a Dual Active Control Plane implementation, of a Multi System LAG. Cisco vPC is a similar technology. VLT is beneficial in environments where the downstream devices like servers or access/distribution switches need to build … Continue reading

Force10 S60 – iSCSI configuration example – stacked, isolated.

. First, I would highly recommend you have a view of my earlier post that summarizes the various (platform independent) optimizations you can implement on an iSCSI fabric. These could be configured upfront, or tried  re-actively in case you have any performance or packet loss issues. the post can be found here https://hasanmansur.com/2012/10/14/switch-fabric-setup-for-equalogic-iscsi-powerconnect-switches/ . Force10 S60 … Continue reading

Layer 3 Switching

. The major difference between a router and an L3 switch is that packet switching in a router is done in software by microprocessor-based engines, whereas packet switching in an L3 switch is done in hardware by specific Application Specific Integrated Circuits (ASICs). Layer 2 switches operate well with reasonably sized broadcast domains/VLANs. The routing … Continue reading

Force10 – Layer 2 Parameters – configuration ( VLANs, STP)

. I will start here with STP. As covered in one of my earlier posts, When configuring Spanning Tree on Force10 switches, you should accommodate whether your fabric is isolated, or inter-connects to other switches. The implications are as follows: On an isolated fabric or isolated switch segments, like the ones often used in iSCSI deployments, the … Continue reading

PowerConnect 8024 – Sample iSCSI Configuration – LAGged (Non-Stacked)

. First, I would highly recommend you have a view of my earlier post that summarizes the various (platform independent) optimizations you can implement on an iSCSI fabric. These could be configured upfront, or tried  re-actively in case you have any performance or packet loss issues. the post can be found here https://hasanmansur.com/2012/10/14/switch-fabric-setup-for-equalogic-iscsi-powerconnect-switches/ This is the … Continue reading

PowerConnect Switch Hang/Freeze – Management Interface unresponsive Troubleshooting

. Are you connecting to the switch via the console port(and if so, are you using the null modem cable provided, or another solution), or is this a telnet/ssh connection that you’re establishing to manage the switch?  If you are connecting via telnet, do we see the same results if we use the console port?   … Continue reading