Category Archives: Data Centers

Topics gathered under this category cover various technologies that are of use in Data Centers deployments. Specifically, Cisco Nexus 5500 series switches configuration guidelines and design considerations are being covered.

Choosing between Dynamic and Static FEX interfaces pinning

Cisco Nexus 2200 Fabric Extenders can be connected to the parent switches using two different modes: Static and Dynamic interfaces pinning. Static pinning mode instructs the switch to virtually split FEX into few blocks of ports and statically associate each block of ports with its own physical uplink. In other words, if one particular uplink fails, a range of FEX ports, associated with this uplink, fail as well. Hence, the word Static. Dynamic pinning modeĀ is based on a Port-Channel logic. In very basic scenario you would have all your physical uplinks associated with a single Port-Channel that will stay up as long as there is at least one working physical uplink. At first glance, difference seems to be obvious and not in the favor of Static mode. But let’s dive into the subject to understand when Static mode becomes handy. Read more …

Configuring Cisco Nexus 5500 series switches with Dual-Homed FEXes

More and more Enterprises come to a decision to deploy Cisco Nexus switches in their corporate data centers. One of the main design considerations relates to Cisco 2200 Fabric Extenders (FEX) connectivity topology. To provide high availability Cisco Nexus 5500 series switches support different options to connect FEXes (all are based on a Virtual Port Channel feature):

  • Straight-Through, where every FEX is connected to a single N5K (Active/Active and Active/Passive servers);
  • Dual-Homed, where each FEX has one or more uplinks to two N5K switches (Active/Passive servers);
  • Enhanced vPC, same as Dual-Homed but with Active/Active servers;

Each option has its own limitations and field of use, but this time we will concentrate our attention on the Dual-Homed FEX topology with Active/Standby Dual-Homed servers. Mainly because I recently deployed a pair of Cisco Nexus 5596UP switches with a number of Cisco 2248 TP-E Fabric Extenders using this approach.

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