Nexus NX-OS Overview Fabric Path Early version of TRILL (Transparent Interconnect of Lots of Links) L2 Ethernet Routing (Not Really Ethernet like TRILL) Uses IS-IS own protocol wrapped n a L3 packet Nexus 7K Dual Supervisors run as a HA Pair Is Primary SUP goes down, standby SUP takes over in a stateful manner Doesn't have to rebuild the control plane (STP, OSFP, Global ARP, and MAC Data Plane= User traffic web or DB traffic no t destined to local switch is not effected SSO Stateful Switch Over Users Graceful Restart / Nonstop Forwarding (NSF) to signal other devices about the switch over Goal is to forward Data Plane traffic while switchover occurs, during a control plane reset Graceful Restart is the standard term for Cisco NSF (also known as Non Stop Routing NSR) 2 Roles in Graceful Restart GR Capable Device Local Device going through the control plane restart GR Helper/Aware Device Remote Device learning about the restart GR Capable signals helper about the restart E.G. OSPF Grace LSA (Type 9 Opaque LSA) Signaling Grace Period of 60 seconds This is how long the helper should wait for the restarting device to come back online Helper continues to forward data plane traffic towards the restarting device until....
No configuration needed for GR/NSF A prerequisite you have to have dual supervisors in the Nexus 7K series switch Commands to check status
 In Service Software Updates/Downgrades SSO or Stateful Switch Over SSO capabilities of the Nexus 7K supervisor to allow hit less NX-OS software upgrades/downgrades This might allow one not having to schedule maintenance windows (I still would) How it would work in Theory 1 Primary SUP with 5.1(x) 2 Standby SUP 1 Standby SUP 2 Active SUP with 6.0 (x) Download image to flash on standby SUP Nexus 7K will perform a SSO to make the standby SUP Active Active SUP now runs new NX-OS version Download image to flash of the new standby SUP (what as the primary) Install image on new standby SUP The whole process will take anywhere from 30-45 minutes depending on if there is EPLD upgrades to perform as well. Always check release notes carefully before performing ISSU/ISSD in production FPGA/EPLD Field programmable gate arrays/Electronic programmable logical devices These devices are on the N7K line card modules which may cause the line card module to reboot If you had you vPC Peerlink on these line cards that would cause all the southbound switches to not have a northbound link out of the network. To see what version you currently have in a N7K series switch enter the following command " show version module (slot#) epld Switch Supervisors while in command line "system switchover" (not a graceful restart) Nexus 5K's 5550 UP (unified ports) Ethernet ports start on port 1 and up Fiber channel ports allocated at the last port (which would include a installed module) and counts down The N5K's will require a reboot to re-allocate port roles (the same the Cisco UCS fabric interconnects) This is the same for the module or platform of the switch Example Slot 1 port 31-32 type FC Nexus 5548/96 support Fabricpath Nexus 2K's No console or VTY ports NX-OS automatically downloads NX-OS from the parent switch (Nexus 5K/7K) NO LOCAL SWITCHING Using a VN-TAG/802.11BR and is not an Ethernet switch  This can impact designs! Is there a lot of East to West traffic Think of a DC with 4 Racks with ToR N2K1 and N2K2 and Servers 1 and 2 in 3 of the racks and the 4th with a N5K EoR design For server 1 to talk to server 2 it would have to go to the upstream N2K1 -------> N5K (EOR)----->N2K2-----> finally to Server 2 all in the same rack. For low latency applications this may not be the best design. How to turn on FEX capabilities in the N5/7K Command "feature fex" "show fex detail" Port from parent switch connecting to the N2k Command "fex associate 100" " interface Ethernet 100/1/1"  The N5K's to N2K's can be crossed and create multiple vPC's, while the N7K's to N2K's have to form a trunk with LACP 802.3ad then create the vPC from the N2k's southbound to the Server. This is supposedly changing with NX-OS 7.0 Gibraltar this will allow the N2K's to be uplinked to two separate N7K's.
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