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C9800-CL best networking practices


Hi guys,

I've been trying to get the new Catalyst controller virtual to work and trying to learn the basics of it also.
However I'd like to ask about the best practices in setting up the thing and if there are clues in the running config of a physical appliance that helps.

The thing is about the interfaces:
- Do you actually need to define 3 interfaces in vmware?
- Is there a reason why the default and the cisco examples leave Gi1 as oob management interface in the global routing table instead of a separate VRF?  And how is this on physical appliances?

So in my first try I bootstrapped the controller using the following
GI1 = OOB interface with IP directly on the interface and route off this interface (VM network VLAN 10)
GI2 = Trunk interface with VLAN 20 as wireless mgmt with IP tagged and no routes (VM network VLAN 4095 all)
GI3 = HA SSO interface disabled because unused (VM network VLAN 50)
And the security features on vmware all accept.
In this setup I could play a bit but I never managed to ping from the VLAN 20 SVI to devices on the same subnet, inside the ESX host or on the LAN. It did grab the mac addresses both ways as I could see in the ARP tables of devices on both ends.
I then f*ed up a bit by deleting the trust point to recreate it.  I couldn't use https to the controller anymore and had to do no http-secure server to regain GUI access on port 80.  I never got the ping to work though

So today I tried again with similar settings in ESX.  However I skipped the day0 and went full cli from the start.
GI1 = routed OOB interface but on management vrf with a default route.
GI2 = trunk carrying a management VLAN and SVI on the global routing table with it's own default route.
GI3 = HA SSO but disabled once again
This time at first I still couldn't ping but I noticed VMWARE had switched interface 2 and 3, so after fixing that I could ping from both vrf's.  I even got an AP connected. However without licensing on this machine I won't get it to work completely but I got very far.  I also noticed you could manage the appliance fully using the wireless mgmt interface.

So once again, best practices on a virtual controller.
Do you use separate interfaces or stick both OOB and Wireless mgmt on the same GI interface but different VLAN?

Another question, since you don't need IP's on your VLANs.  When you do add an IP to an interface, can you put an IP helper on that interface to forward DHCP out the wireless management interface or another one closer to the DHCP server?

4 Replies 4


I am running into some of the same issues as you, though I only have a GigabitEthernet1 "physical" interface. I followed this guide to set it up ( using the CLI. As soon as I add an SVI and enable it, I lose access to the management interface. As soon as I shut that VLAN interface, the management interface is accessible again. We have two 9800-40 controllers on order and I am also curious if I will run into this on the physical hardware.

I am confused about interfaces, too. We have two 9800CL in a cluster running on kvm. One interface serves for management access, another is trunk with the wireless management vlan and the third is used for HA.
- Does the order of the interfaces matter? In my demployment G2 is for HA as the hypervisor interchanged G2 and G3.

- What is the purpose of the wireless management interface? I played around and set the management interface as trustpoint. Access Points are able to join. As we do not switch centrally we do not need other Vlans than the one for management on the Controllers. What is the reason for adding a seperate wireless management interface? 


Regarding the following post it seems to work without issues. So I'll give it a try with only one interface serving as trustpoint for access points and for device management.


Given that it's 2 years old, I assume your questions are answered. "What is the purpose of the wireless management interface on Cisco 9800's", just in case. Wireless LAN Controllers, Cisco 9800's included, manage APs. This is the interface used for CAPWAP communication with your APs and requires a certificate "TrustPoint" to be attached to the interface for APs to join and communicate with the controller. If you are using Cisco 9800_CL controllers there is no factory MIC installed, you have to use the setup script to define time, country code, and wireless management interface settings, and it will generate the cert = trustpoint,  attach to the interface you specify. This is the interface you want your APs pointed to. On the 9800_CL, it's a VLAN/SVI which is created for this purpose. Really on any of the 9800's you want to use EtherChannel for all data communication including your AP Mgmt interface, so would be VLAN/SVI on your Etherchannel group. 9800_CL that's Gig2 by default should be an 802.1Q trunk w promiscuous mode enabled on your vSwitch in VMWARE. There's also an OOB - Out of Band Management interface, Gig1 used to manage the controller itself, and used as the default source interface for AAA services, and telemetry. on the 9800_CL Gig3 is for HA purposes. Technically you could add several other interfaces up to 11, but this is the default on the 9800_CL. If you go back far enough AireOS used to require a separate management interface, to AP Manager interface, and then they started just using 1 interface for both management of the controller, and AP management, but it is important to understand AP managers are used for CAPWAP coms to the APs. Hope this helps someone searching for this issue. A student in my C9800 class at WiFi Training told me he noticed this question, so figured I would help the next visitor. 

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 - This will not answer all your questions but you can always review the current  9800-CL  configuration with the CLI command : show  tech wireless , have the output analyzed by  , please note do not use classical show tech-support (short version) , use the command denoted in green for Wireless Analyzer. You  will get lots of useful advisories. 


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