Re: DNA Center cluster link

eagles-nest · ‎08-29-2019

Hi

I've watched a Cisco video on installing DNAC and it shows enp10s0 being used as a cluster link but the presenter assigns 1.1.1.1/24 to the link with no gateway. In documentation it shows that for a single node the cluster link doesn't need to be connected which would make sense because at this time I have no other cluster members to communicate with.

When I log into the GUI for the first time in the system settings System 360 area I see the host defined as the cluster link IP address of 1.1.1.1 which is not routeable on my network.

When I then go to Design - Network settings there's a box to tick to define DNAC as a syslog and snmp server. However, when I push this config out via the provision process I see 1.1.1.1 defined as my snmp and syslog servers. Since the 1.1.1.0 subnet is not routeable on my network the DNAC address of 1.1.1.1 is not reachable.

Surely DNAC should push out the Enterprise interface IP as the syslog and snmp server address to use to reach DNAC? I thought since the cluster link is just needed for inter-DNAC comms then it doesn't need to be reachable and in the case of a single node cluster doesn't even need to be patched into the network.

Thanks for any input, Stuart.

Pavan Siripuram · ‎08-30-2019

The Assumption for Cluster link is that all the DNA Centers would be in same network , that is the reason the default GW might not be mentioned , Anyhow even in the standalone we recommend to have cluster link up as in future customers might move to three node cluster.

Also if its LAB then you can change the cluster link same as Enterprise link , as by default this port would be up so Enterprise ip should be pushed as SNMP or syslog server , But yes we need to investigate why cluster ip(non routable) was getting pushed instead of Enterprise ip which is routable in your network , probably better to open a TAC case.

eagles-nest · ‎09-02-2019

Thank you Pavan

So just to confirm. I can configure the Cluster link IP address in the same subnet as the enterprise link. Is that correct?

Thanks, Stuart.

Pavan Siripuram · ‎09-02-2019

you don't have configure separate cluster link ,In Lab setup you can reuse the Enterprise Link for Cluster communication also , if you do maglev-config update and go to the enterprise link and select cluster option . once done Cisco DNA Center will start using this link for both enterprise and cluster .

NOTE : This i am suggesting only for lab environments , in production please follow the cisco best practices to configure different links.

eagles-nest · ‎09-04-2019

Thank you again Pavan

I found a Cisco video that stepped through the install process. When it got to a page that asked for VIP addresses the presenter put in 3 addresses. One for each of the Cluster link, Enterprise and GUI links. These were in addition to the addresses configured on each interface and each interface address came from a different subnet.

I believe I may have gone wrong in my install by only assigning a cluster link VIP as 1.1.1.1. Would this perhaps be why it is the address shown in the GUI system settings area? If I had correctly assigned a VIP for the Enterprise link do you think this would have been shown in the system settings area and pushed out as the snmp and syslog server addresses?

I assigned the cluster link a 1.1.1.x address because the install guide suggested this link doesn't need connected in a single node install. I thought its addressing was irrelevant. However, in not applying an Enterprise link VIP have I forced the DNAC to use the only available VIP address which is the cluster link.

So really by following the video I found I should apply the following addressing

Enterprise link -Routable IP address and additional VIP address.

Cluster link - IP address and VIP address. Not required to be routable.

GUI interface - Routable IP address and VIP

Cluster and services subnets. 2 z /21 subnets to be used internally on DNAC. Not required to be routed.

It looks like I may be able to update the VIP addresses by running the maglev setup again but I can't change the cluster link address without a rebuild. Does that sound correct?

Thanks again for any input, Stuart.

Pavan Siripuram · ‎09-04-2019

please see inline:

I believe I may have gone wrong in my install by only assigning a cluster link VIP as 1.1.1.1. Would this perhaps be why it is the address shown in the GUI system settings area? If I had correctly assigned a VIP for the Enterprise link do you think this would have been shown in the system settings area and pushed out as the snmp and syslog server addresses?

Pavan : Yes , if you have configured VIP for enterprise then yes it would have been pushed , if you are start configuring the VIP addresses then you have to configure them for all the interfaces,

I assigned the cluster link a 1.1.1.x address because the install guide suggested this link doesn't need connected in a single node install. I thought its addressing was irrelevant. However, in not applying an Enterprise link VIP have I forced the DNAC to use the only available VIP address which is the cluster link.

Pavan : In a single node cluster configuring VIP is optional , but as i mentioned earlier if you have configured on one interface then you have to start configuring on others too , if not you might see the behaviour which you have seen.

The below what you mentioned is correct , And also there will be one more interface called Cloud interface which will be used for internet connectivity , this is optional , if you have internet connectivity through GUI interface this can be ignored , if not then you need this to be configured so DNA center can download the cloud updates.

"Enterprise link -Routable IP address and additional VIP address.

Cluster link - IP address and VIP address. Not required to be routable.

GUI interface - Routable IP address and VIP

Cluster and services subnets. 2 z /21 subnets to be used internally on DNAC. Not required to be routed."

yes you can't change the VIP addresses once configured and yes you have to rebuild if you have to change the VIP addresses.

mglanzrock · ‎09-25-2020

Hi all, I too am getting ready to setup a three node cluster in my data center. I just wanted to confirm again for the "CLUSTER LINK" that this subnet does not in fact need to be routable across my network, correct? Almost more just of a layer 2 connection for all three nodes to communicate? Thank you in advance.

"Enterprise link -Routable IP address and additional VIP address.

Cluster link - IP address and VIP address. Not required to be routable.

GUI interface - Routable IP address and VIP

Cluster and services subnets. 2 z /21 subnets to be used internally on DNAC. Not required to be routed."

Preston Chilcote · ‎09-25-2020

You are correct, mglanzrock. The Cluster Link is used only for the 3 nodes of the cluster to talk among themselves. Nothing else in the network needs to be able to reach that subnet.

Jonathan Cuthbert · ‎09-12-2019

It looks like you set up this device as a transit control plane node. That would be the only time you would have the T icon badge.

Did you go through a workflow similar to the screen shot below?