Thursday, 6 August 2015

Using CDP to trace physical networking connections in Netapp Data ONTAP

Have you ever been on a Data ONTAP system without a clear idea of how the physical network is connected, and wish you could interrogate your network to try and find out? If so, CDP – the Cisco Discovery Protocol – might be the help you’re looking for. This can be very useful on systems with large or complex Ethernet configurations.
Once CDP is enabled in Data ONTAP, your Cisco switches will become aware of which NetApp systems are cabled to which ports. It wil know both the source port (on the NetApp) and the destination port (on the Cisco switch).
CDP has been available in Netapp Data ONTAP since version 7.3.3, and is supported in both 7-mode and cDOT, and it’s simply enabled with an option command.
To enable CDP in 7-mode:
options cdpd.enable on
To enable CDP in cDOT:
node run -node * options cdpd.enable on
NOTE that the command is cdpd.enable, not cdp.enable
The nice thing about NetApp’s CDP implementation is that it is bi-directional. That means you can query CDP from either the Cisco switch or the NetApp controller and see information — meaning you don’t have to rely on a network administrator to provide you the information!
To view CDP information from 7-mode Data ONTAP, you would use the cdpd show-neighbors command.
Here’s some sample output:
nas1> cdpd show-neighbors
Local  Remote          Remote                 Remote           Hold  Remote   
Port   Device          Interface              Platform         Time  Capability
------ --------------- ---------------------- ---------------- ----- ----------
e0M    charles         e0M                    FAS3170           146   H        
e0M    nane-cat4948-sw GigabitEthernet1/8     cisco WS-C4948-.  174   RSI      
e3a    nane-nx5010-sw. Ethernet1/4            N5K-C5010P-BF     173   SI       
e4a    nane-nx5010-sw. Ethernet1/14           N5K-C5010P-BF     177   SI
Note that we can see that Filer’s HA partner, charles, is in the output. Here we can see that e0M is cabled to port Giga1/8 on nane-cat4948, whereas e3a and e4a are cabled to Eth1/4 andEth1/14 on nane-nx5010-sw respectively.
This is incredibly useful information if you’re ever trying to track down how a system is cabled!
To view CDP information from clustered Data ONTAP, use the run -node nodeName cdpd show-neighbors command.
The output is the same format as in 7-mode:
dot83cm::> node run -node local cdpd show-neighbors
Local  Remote          Remote                 Remote           Hold  Remote   
Port   Device          Interface              Platform         Time  Capability
------ --------------- ---------------------- ---------------- ----- ----------
e6a    nane-nx5010-sw. Ethernet1/12           N5K-C5010P-BF     145   SI       
e6b    nane-nx5010-sw. Ethernet1/5            N5K-C5010P-BF     145   SI       
e4a    dot83cm-01      e4a                    FAS3240           161   H        
e4b    dot83cm-01      e4b                    FAS3240           161   H        
e0a    nane-cat4948-s. GigabitEthernet1/9     cisco WS-C4948-.  168   RSI
In this case, e6a and e6b go to the same switch, with e4a and e4b going to the other node in this HA pair — that’s my switchless cluster interconnect. e0a goes to an older Catalyst switch.

To view CDP information from Cisco IOS or NX-OS, use the show cdp neighbors command.
Sample output:
nane-nx5010-sw# show cdp neighbors
Capability Codes: R - Router, T - Trans-Bridge, B - Source-Route-Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater,
                  V - VoIP-Phone, D - Remotely-Managed-Device,
                  s - Supports-STP-Dispute, M - Two-port Mac Relay

Device ID              Local Intrfce   Hldtme  Capability  Platform      Port ID
US-WLM-LS02            mgmt0           124     R S I       WS-C6509      Gig5/1
nane-cat4948-sw        Eth1/2          179     R S I       WS-C4948-10GE Ten1/49
dot83cm-01             Eth1/3          163     H           FAS3240       e6b   
mystic                 Eth1/4          127     H           FAS3170       e3a   
dot83cm-02             Eth1/5          158     H           FAS3240       e6b

In IOS/NX-OS, you may wish to run show cdp neighbors detail to gather more information.

To view CDP information using the vSphere/VI Client: Connect to the vCenter Server/Virtual Center or ESX host using the vSphere/VI Client.
·         Select the ESX host in the Inventory.
·         Click the Configuration tab.
·         Click Networking.
·         Click the Info icon to the right of the vSwitch, under Properties.
More detailed information about the output of CDP commands can be found in the relevant Ontap Network Management Guide, Cisco and VMware documentation.

Hope you don’t have to trace the network cables the hard way anymore!

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