First foray into Cisco Nexus gear

We’ve just some Nexus 3548-X switches and being my first hands on experience with these devices this post will serve as a small notebook of things I’ve deemed worth jotting down.

Interface Naming and Status

The first thing which stood out was that all interfaces are named Ethernet. As these switches are populated with SFP+ ports, it no longer makes sense to call a port FastEthernet 1/1 or GigabitEthernet 1/1 since the port speed will depend on the SFP+ module used. It is also worth noting that a 10Gbps SFP+ will only permit 10Gbps connectivity - you cannot connect a 10Gbps SFP+ to a GigabitEthernet port/SFP and have it negotiate down to 1Gbps.

Another difference is that show ip int brief will only show layer 3 interfaces (including SVIs) under NX-OS.

switch(config)# show ip int brief
IP Interface Status for VRF "default"(1)
Interface            IP Address      Interface Status
Vlan10               1.1.1.1         protocol-down/link-down/admin-down

To show the status of all interfaces, show int brief can be used. This command is also useful as it shows the VLAN and reason for the interface status - eg, an SFP not being present.

switch(config)# show int brief

--------------------------------------------------------------------------------
Ethernet      VLAN   Type Mode   Status  Reason                   Speed     Port
Interface                                                                   Ch #
--------------------------------------------------------------------------------
Eth1/1        1       eth  access down    SFP not inserted            10G(D) --
Eth1/2        1       eth  access down    SFP not inserted            10G(D) --
Eth1/3        1       eth  access down    SFP not inserted            10G(D) --
Eth1/4        1       eth  access down    SFP not inserted            10G(D) --
Eth1/5        1       eth  access down    Link not connected          10G(D) --

Nexus Features

NX-OS modular, meaning many features, or modules are disabled by default. For example, if SVIs are required, the interface-vlan must be enabled. Otherwise the command will be rejected.

switch(config)# int vlan 10
                    ^
Invalid interface format at '^' marker.

switch(config)# feature interface-vlan
switch(config)# int vlan 10
switch(config-if)# ip address 1.1.1.1 255.255.255.0 ?

All features, and whether they’re enabled or disabled can be shown with show feature. If you run feature ? from configure mode, there is also a description of each feature.

switch(config)# feature ?
    bash-shell             Enable/Disable bash-shell
    bfd                    Bfd
    bgp                    Enable/Disable Border Gateway Protocol (BGP)
    dhcp                   Enable/Disable DHCP Snooping
    eigrp                  Enable/Disable Enhanced Interior Gateway Routing Protocol (EIGRP)
    evmed                  Enable/Disable Generic event detectors
    fcoe                   Enable/Disable FCoE/FC feature
    fcoe-npv               Enable/Disable FCoE NPV feature
    flexlink               Enable/Disable Flexlink
    hsrp                   Enable/Disable Hot Standby Router Protocol (HSRP)
    interface-vlan         Enable/Disable interface vlan
    lacp                   Enable/Disable LACP
    lldp                   Enable/Disable LLDP
    msdp                   Enable/Disable Multicast Source Discovery Protocol (MSDP)
    nat                    Enable/Disable NAT
    ntp                    Enable/Disable NTP
    nv                     Enable/Disable NV Overlay
    nxapi                  Enable/Disable nxapi
    ospf                   Enable/Disable Open Shortest Path First Protocol (OSPF)
    ospfv3                 Enable/Disable Open Shortest Path First Version 3 Protocol (OSPFv3)
    password               Credential(s) for the user(s)/device(s)
    pbr                    Enable/Disable Policy Based Routing(PBR)
    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)
    scheduler              Enable/Disable scheduler
    scp-server             Enable/Disable SCP server
    sflow                  Enable/Disable sFlow agent
    ssh                    Enable/Disable ssh
    tacacs+                Enable/Disable tacacs+
    telnet                 Enable/Disable telnet
    tunnel                 Enable/Disable Tunnel Manager
    udld                   Enable/Disable UDLD
    vn-segment-vlan-based  Enable/Disable VLAN based VN segment
    vpc                    Enable/Disable VPC (Virtual Port Channel)
    vrrp                   Enable/Disable Virtual Router Redundancy Protocol (VRRP)
    vtp                    Enable/Disable Vlan Trunking Protocol (VTP)

Nexus 3545-X boot sequence

This is purely as a reference so I have a known good sequence if I ever encounter something out of the ordinary.

At this point we need to enter Y to skip Power On Auto Provisioning.