Connecting FEX (5k to 2k)

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Nexus-PLineI was pretty excited to get my hands on some of the Cisco Nexus product line which focuses on switching in the data center. The gear I have is an evaluation unit so I made some notes and one thing I was impressed is how easy it is to connect a Nexus 5K to a Nexus 2k also known as a fabric extender. I have kept it simple as the gear I have is a single Nexus 5596 along with a single Nexus 224TP-E who needs redundancy right? So in this post I'll explain how to connect a 5k Nexus to a 2k extender. Let’s get started! So I needed a couple of SFPs as the only way to connect the 5k to the 2k is a FET-10G SFP along with that was some multimode fiber (OM3) with LC connectors. Looking at the simple diagram below our end goal is to be able to configure the 2k from the 5k. That is the point of the 2k extenders less switches to manage in the data center.5k to 2kOnce we have made the physical connections lets power both switches on, we won't need to worry about the 2k switch at all as along we have a physical connection to a parent switch the 5k in our case, but that also could be 7k switch. Just an FYI, I've already ran through the simple CLI wizard to setup a username and password but other than that let's get configuring by entering the familiar command "config t" [code]User Access Verification demo5k login: admin Password: Cisco Nexus Operating System (NX-OS) Software TAC support: Copyright (c) 2002-2013, Cisco Systems, Inc. All rights reserved. The copyrights to certain works contained in this software are owned by other third parties and used and distributed under license. Certain components of this software are licensed under the GNU General Public License (GPL) version 2.0 or the GNU Lesser General Public License (LGPL) Version 2.1. A copy of each such license is available at and demo5k# config t[/code] Now in configuration mode we have to turn on a feature in the NX-OS to enable FEX, we do this by issuing the "feature FEX" command. The Nexus runs on efficiency and only loads what it needs or configured. This is familiar approach that Linux uses which loads what is installed and nothing else.  In the output below we can see all the features that the NX-OS supports followed by the command to turn on FEX. [code] Enter configuration commands, one per line. End with CNTL/Z. demo5k(config)# feature ? bgp Enable/Disable Border Gateway Protocol (BGP) cts Enable/Disable CTS dhcp Enable/Disable DHCP Snooping dot1x Enable/Disable dot1x eigrp Enable/Disable Enhanced Interior Gateway Routing Protocol (EIGRP) fcoe Enable/Disable FCoE/FC feature fcoe-npv Enable/Disable FCoE NPV feature fex Enable/Disable FEX flexlink Enable/Disable Flexlink hsrp Enable/Disable Hot Standby Router Protocol (HSRP) http-server Enable/Disable http-server interface-vlan Enable/Disable interface vlan lacp Enable/Disable LACP msdp Enable/Disable Multicast Source Discovery Protocol (MSDP) ntp Enable/Disable NTP ospf Enable/Disable Open Shortest Path First Protocol (OSPF) ospfv3 Enable/Disable Open Shortest Path First Version 3 Protocol (OSPFv3) pim Enable/Disable Protocol Independent Multicast (PIM) port-security Enable/Disable port-security private-vlan Enable/Disable private-vlan privilege Enable/Disable IOS type privilege level support ptp Enable/Disable PTP rip Enable/Disable Routing Information Protocol (RIP) scp-server Enable/Disable SCP server sftp-server Enable/Disable SFTP server ssh Enable/Disable ssh tacacs+ Enable/Disable tacacs+ telnet Enable/Disable telnet udld Enable/Disable UDLD vpc Enable/Disable VPC (Virtual Port Channel) vrrp Enable/Disable Virtual Router Redundancy Protocol (VRRP) vtp Enable/Disable Vlan Trunking Protocol (VTP) demo5k(config)# feature fex demo5k(config)#[/code] Now that our FEX feature is active let's configure the port that has the 2k connected and in this example I have it as ethernet port 48 on our 5k. The commands are petty simple, I first want to go into interface followed by changing the mode of interface and finally giving the interface a FEX associate ID. :!:NOTE: Since this design is a single stack we need to issue the FEX associate command on the physical interface. If you want redundancy you would usually put the FEX associate command with channel-groups and vPCs. Another helpful FYI is if you have channel-groups you don't need to put the FEX associate command on the physical interface. [code]demo5k(config)# interface ethernet1/48 demo5k(config-if)# switchport mode fex-fabric demo5k(config-if)# fex associate 100 demo5k(config-if)# exit demo5k(config)#[/code] Give it a couple of minutes and you should see the 2k come online :) [code]2013 Dec 01 07:28:37 demo5k %$ VDC-1 %$ %PFMA-2-FEX_STATUS: Fex 100 is online 2013 Dec 01 07:28:37 demo5k %$ VDC-1 %$ %NOHMS-2-NOHMS_ENV_FEX_ONLINE: FEX-100 On-line 2013 Dec 01 07:28:39 demo5k %$ VDC-1 %$ %PFMA-2-FEX_STATUS: Fex 100 is online[/code] Let's verify that our FEX is all good by issuing "show fex 100" which shows the FEX and the 5k version. (Notice they match versions) You can also find the serial number, model number, the number links and the status of fabric when using this command. (The 5K) [code]demo5k# show fex 100 FEX: 100 Description: FEX0100 state: Online FEX version: 6.0(2)N1(2) [Switch version: 6.0(2)N1(2)] Extender Serial: SSI153804CQ Extender Model: N2K-C2248TP-E-1GE, Part No: 73-13671-01 Pinning-mode: static Max-links: 1 Fabric port for control traffic: Eth1/48 FCoE Admin: false FCoE Oper: true FCoE FEX AA Configured: false Fabric interface state: Eth1/48 - Interface Up. State: Active demo5k# show fex FEX FEX FEX FEX Number Description State Model Serial ------------------------------------------------------------------------ 100 FEX0100 Online N2K-C2248TP-E-1GE SSI153804CQ[/code] You can also go into detail on the FEX by issuing the "show fex detail" which shows almost the same information has "show fex" but it includes the FEX ports, the status of those FEX ports and what port the fabric is connected. (Also called the 5k) as well as helpful logs for the 2k at the end of command. [code]demo5k# show fex detail FEX: 100 Description: FEX0100 state: Online FEX version: 6.0(2)N1(2) [Switch version: 6.0(2)N1(2)] FEX Interim version: 6.0(2)N1(2) Switch Interim version: 6.0(2)N1(2) Extender Serial: SSI153804CQ Extender Model: N2K-C2248TP-E-1GE, Part No: 73-13671-01 Card Id: 149, Mac Addr: 70:81:05:00:99:42, Num Macs: 64 Module Sw Gen: 12594 [Switch Sw Gen: 21] post level: complete pinning-mode: static Max-links: 1 Fabric port for control traffic: Eth1/48 FCoE Admin: false FCoE Oper: true FCoE FEX AA Configured: false Fabric interface state: Eth1/48 - Interface Up. State: Active Fex Port State Fabric Port Eth100/1/1 Down Eth1/48 Eth100/1/2 Down Eth1/48 Eth100/1/3 Down Eth1/48 Eth100/1/4 Down Eth1/48 Eth100/1/5 Down Eth1/48 Eth100/1/6 Down Eth1/48 Eth100/1/7 Down Eth1/48 Eth100/1/8 Down Eth1/48 Eth100/1/9 Down Eth1/48 Eth100/1/10 Down Eth1/48 Eth100/1/11 Down Eth1/48 Eth100/1/12 Down Eth1/48 Eth100/1/13 Down Eth1/48 Eth100/1/14 Down Eth1/48 Eth100/1/15 Down Eth1/48 Eth100/1/16 Down Eth1/48 Eth100/1/17 Down Eth1/48 Eth100/1/18 Down Eth1/48 Eth100/1/19 Down Eth1/48 Eth100/1/20 Down Eth1/48 Eth100/1/21 Down Eth1/48 Eth100/1/22 Down Eth1/48 Eth100/1/23 Down Eth1/48 Eth100/1/24 Down Eth1/48 Eth100/1/25 Down Eth1/48 Eth100/1/26 Down Eth1/48 Eth100/1/27 Down Eth1/48 Eth100/1/28 Down Eth1/48 Eth100/1/29 Down Eth1/48 Eth100/1/30 Down Eth1/48 Eth100/1/31 Down Eth1/48 Eth100/1/32 Down Eth1/48 Eth100/1/33 Down Eth1/48 Eth100/1/34 Down Eth1/48 Eth100/1/35 Down Eth1/48 Eth100/1/36 Down Eth1/48 Eth100/1/37 Down Eth1/48 Eth100/1/38 Down Eth1/48 Eth100/1/39 Down Eth1/48 Eth100/1/40 Down Eth1/48 Eth100/1/41 Down Eth1/48 Eth100/1/42 Down Eth1/48 Eth100/1/43 Down Eth1/48 Eth100/1/44 Down Eth1/48 Eth100/1/45 Down Eth1/48 Eth100/1/46 Down Eth1/48 Eth100/1/47 Down Eth1/48 Eth100/1/48 Down Eth1/48 Logs: 12/01/2013 07:28:31.344277: Module register received 12/01/2013 07:28:31.347237: Registration response sent 12/01/2013 07:28:31.696577: create module inserted event. 12/01/2013 07:28:31.697697: Module Online Sequence 12/01/2013 07:28:37.285556: Module Online[/code] Believe it or not you now have a working 5k with a connected FEX, you could plug devices in and be ready to roll on a single stack 2k and 5k. One thing I've been impressed with the NX-OS it's that familiar feeling of IOS with some improved differences, Cisco has good documentation on the common and different features when comparing NX-OS and IOS which is below. Like always I hope this post is helpful and I have a couple more Nexus posts in the works but other than that enjoy the remaining of 2013! Cisco Nexus 7000 NX-OS/IOS Comparison Tech Notes


Farhan -

Quick question: why port 1/48 down? I thought you configured that interface/port?

#### [Ryan]( "") -

Hey Farhan, Port 1/48 is not down on the 5k but on the 2k port 100/1/48 is down, this is a 1GB copper port and in the example I had nothing connected to the 2k. The 2k has four FEX ports that can be connected to a 5k or a 7k, however in this example I did not issue a command that shows the FEX port status, I'll do some digging in finding an example but from what I can tell I think the "show interface fex-fabric" would show what uplink it is connected to and the status of the FEX link. Hope that Helps.

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