3850 connecting to nexus 9k

[David Bell]

Hello experts.

I am trying to connect a Catalyst 3850 to Nexus 9K.

In the main this has been successful, unfortunately whilst the 9K sees the CDP neighbour fine, and can ping the 3850 switch management address I am unable to ping the 3850 from other subnets.

=== On the Nexus 9K ===

interface port-channel5
  description *** Server Room cab 4 top ***
  switchport mode trunk
  switchport trunk native vlan 111
  switchport trunk allowed vlan 10,111,604,631,999
  vpc 5

interface Ethernet1/5
  description *** Server Room cab 4 top ***
  switchport mode trunk
  switchport trunk native vlan 111
  switchport trunk allowed vlan 10,111,604,631,999
  channel-group 5 mode active

show cdp neighbors interface ethernet 1/5 detail
----------------------------------------
Device ID:SGHServer04-Top-3850.xnlg.nhs.uk
VTP Management Domain Name: SGH1

Interface address(es):
    IPv4 Address: ##.##.##.##
Platform: cisco WS-C3850-48P, Capabilities: Switch IGMP Filtering
Interface: Ethernet1/5, Port ID (outgoing port): TenGigabitEthernet1/1/3
Holdtime: 138 sec

Version:
Cisco IOS Software, Catalyst L3 Switch Software (CAT3K_CAA-UNIVERSALK9-M), Version 15.2(2)E8, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2018 by Cisco Systems, Inc.
Compiled Mon 22-Jan-18 05:56 by prod_rel_team

Advertisement Version: 2

Native VLAN: 111
Duplex: full
Mgmt address(es):
    IPv4 Address: ##.##.##.##

The switch configuration is very simple, trunk with the same native vlan 111, and single management IP address in vlan 999.

I seem to be missing s simple trick, any advice ?

With regards

Dave 

[Reza Sharifi]

Hi,

Where is the layer-3 interfaces (SVIs) for each vlan?

Can you post configs?

HTH

[David Bell]

Thanks for responding.

The management interface of the 3850 switch is in VLAN 999

On the 9K I have:

interface Vlan1
  no ip redirects
  no ipv6 redirects

interface Vlan966
  description L3-transit-to-Core
  no shutdown
  no ip redirects
  ip address 10.##.##.##/28
  hsrp 3
    priority 110
    ip 10.##.##.##

interface Vlan999
  description Management
  no shutdown
  ip address 10.##.##.##/23

I am unable to ping from a client VLAN, eg vlan 9 which is just hosts on a separate subnet (routed by a 6500 chassis) to the management address of the switch on VLAN 999.

The 9K can ping the switch fine, and sees the CDP neighbour fine - so I agree its a routing issue, but I'm no expert .

Kind regards

Dave

[Reza Sharifi]

Hi,

In order for other subnets to be able to reach vlan 999 on the 3850, the 3850 need to have a default gateway.

ip default-gateway <ip address of the gateway>

Does the 3850 have this command?

HTH

[David Bell]

Thanks Reza.

Yes the 3850 has the default gateway configured. If I connect the 3850 to another device I can ping and manage the switch etc. The problem occurs when I connect the 3850 switch to the Nexus 9K, so I believe I've missed a command, just not sure what I've missed. Thanks for taking the time to reply, appreciated. Regards Dave