Connect Two nexus 9K switches towards 9600 Core switch.

[prakashrajasekaran2807]

HI Folks,

I need to connect two of my nexus 9k switches to cisco 9600 chassis switch which have two line cards with it.

can any body help to resolve my doubt. i have  attcahed my connectivity and configuration below 

i  have the below configuration

Nexus :

Nexus-1:
Nexus-1(config)# interface eth 1/3
Nexus-1(config-if)# channel-group 100 mode active

Nexus-1(config)# interface eth 1/4
Nexus-1(config-if)# channel-group 101 mode active

!
Nexus-1(config-if)# interface port-channel 100
Nexus-1(config-if)# switchport
Nexus-1(config-if)# switchport mode trunk
Nexus-1(config-if)# switchport trunk allowed vlan all
Nexus-1(config-if)# vpc 100

Nexus-1(config-if)# interface port-channel 101
Nexus-1(config-if)# switchport
Nexus-1(config-if)# switchport mode trunk
Nexus-1(config-if)# switchport trunk allowed vlan all
Nexus-1(config-if)# vpc 101

Nexus-2:
Nexus-2(config)# interface eth 1/3
Nexus-2(config-if)# channel-group 100 mode active

Nexus-1(config)# interface eth 1/4
Nexus-1(config-if)# channel-group 101 mode active
!
Nexus-2(config-if)# interface port-channel 100
Nexus-2(config-if)# switchport
Nexus-2(config-if)# switchport mode trunk
Nexus-2(config-if)# switchport trunk allowed vlan all
Nexus-2(config-if)# vpc 100

Nexus-2(config-if)# interface port-channel 101
Nexus-2(config-if)# switchport
Nexus-2(config-if)# switchport mode trunk
Nexus-2(config-if)# switchport trunk allowed vlan all
Nexus-2(config-if)# vpc 101

Cisco 9606R core:

interface Port-channel3
description PO-UPlink-NX-A
switchport mode trunk
shutdown
end

CORESW-01# sh run int port-channel 4
Building configuration...

Current configuration : 92 bytes
!
interface Port-channel4
description PO-UPlink-NX-B
switchport mode trunk
shutdown
end

[mohammedshahidali88]

Create Port-channel 100 & 101 on 9600 Core Switch in active mode. And 9600 Physical interfaces to the port-channel 100 and 101.

[prakashrajasekaran2807]

Yes i can create it. but i am bit confused in connectivity part. can you guide to that.

[prakashrajasekaran2807]

Can you share a example  config like that for the below connectivity so that i can understand better.. thanks in advance. 

[mohammedshahidali88 · Accepted solution]

Below is the simple config, hope this will resolve your issue.

NEXUS A & B

feature telnet
feature interface-vlan
feature lacp
feature lldp
feature vtp


NEXUS A:

interface port-channel100
description ********To Core Switch***********
switchport mode trunk


interface Ethernet1/19 -20
switchport mode trunk
channel-group 100 mode active
no shutdown


NEXUS B:

interface port-channel101
description ********To Core Switch***********
switchport mode trunk


interface Ethernet1/19 -20
switchport mode trunk
channel-group 101 mode active
no shutdown

CORE SWITCH

interface Port-channel100
description ********Port-Channel to Nexus A******
switchport mode trunk

interface Port-channel101
description ********Port-Channel to Nexus B******
switchport mode trunk


interface TenGigabitEthernet1/1/0/1 (CoreSwitch1/line card1/0/interface1)
description ********UPlink from Nexus A********
switchport mode trunk
channel-group 100 mode active

interface TenGigabitEthernet1/1/0/2 (CoreSwitch1/line card1/0/interface2)
description ********UPlink from Nexus B********
switchport mode trunk
channel-group 101 mode active

interface TenGigabitEthernet1/2/0/1 (CoreSwitch1/line card2/0/interface1)
description ********UPlink from Nexus A********
switchport mode trunk
channel-group 100 mode active

interface TenGigabitEthernet1/2/0/2 (CoreSwitch1/line card2/0/interface2)
description ********UPlink from Nexus B********
switchport mode trunk
channel-group 101 mode active

[mohammedshahidali88]

Beginning with Cisco NX-OS Release 7.0(3)I7(1), Link Aggregation Control Protocol (LACP) vPC convergence feature is supported on Cisco Nexus 9200 and 9300 Series Switches. You can configure LACP vPC convergence feature for more efficient use of port channels by reducing convergence time of vPC port channel for member link going down and first member bring up.

Beginning with Cisco NX-OS Release 7.0(3)I7(5), Link Aggregation Control Protocol (LACP) vPC convergence feature is supported on Cisco Nexus 9500 Series Switches with 9700-EX and 9700-FX line cards. This feature is not supported on Nexus 9500 with 9400, 9500, and 9600 and 9600-R line cards.

When you configure LACP vPC convergence on a Cisco Nexus 9000 switch, it waits until all the VLANs are initialized and programmed and then send LACP sync PDU, which will start sending traffic to the VPC domain without drops. You may configure the lacp vpc-convergence command in a VXLAN and non-VXLAN environments that have vPC port-channels to hosts that support LACP.


https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/7-x/interfaces/configuration/guide/b_Cisco_Nexus_9000_Series_NX-OS_Interfaces_Configuration_Guide_7x/b_Cisco_Nexus_9000_Series_NX-OS_Interfaces_Configuration_Guide_7x_chapter_0100...

[Sergiu.Daniluk]

Hi @prakashrajasekaran2807 

Respectful, I disagree with recommendation of @mohammedshahidali88. Why use two individual port-channels, when you can take advantage of vPC on your Nexus 9K switches?

Assuming that your N9K switches are configured in a vPC domain (and probably they are since you have vpc configured under port-channels), what you have to do is configure your Nexus switches like this:

Both NexusA and NexusB will have this config:

interface Ethernet1/19 -20
switchport mode trunk
channel-group 100 mode active
no shutdown

interface port-channel100
switchport mode trunk
vpc 100

Your C9600 config will look like:

interface TenGigabitEthernet1/1/0/1
description ********UPlink from Nexus A********
switchport mode trunk
channel-group 100 mode active 

interface TenGigabitEthernet1/1/0/2
description ********UPlink from Nexus B********
switchport mode trunk
channel-group 100 mode active 

interface TenGigabitEthernet1/2/0/1 
description ********UPlink from Nexus A********
switchport mode trunk
channel-group 100 mode active

interface TenGigabitEthernet1/2/0/2 
description ********UPlink from Nexus B********
switchport mode trunk
channel-group 100 mode active 

interface Port-channel100
description PO-uplink to Nexus vPC
switchport mode trunk

This way your logical topology will look like Nexus 9k ===== PO100 ==== C9600

This is the power of vPC. You will have active/active forwarding on both N9K switches and on all links.

Stay safe,

Sergiu

[prakashrajasekaran2807]

HI ,

Thanks

In this case, the catalyst 9606R will  take both Nexus as single host. am i correct !

if we applied a single Vpc how about reduancy and STP loop avoidance. is there any port block  happen

[Sergiu.Daniluk]

That's correct. when you attach a switch (in your case C9606) to 2x nexus switches using vPC, the C9606 will see both N9K as a single virtual switch. Plus all 4 links will be active from STP perspective.

Redundancy and STP is all handled by the vPC itself. If you are not familiar with vPC I would recommend reading the following document:

https://www.cisco.com/c/dam/en/us/td/docs/switches/datacenter/sw/design/vpc_design/vpc_best_practices_design_guide.pdf  - it was written for N7K, but the concepts apply for all Nexus platforms. It's a one day reading book. Once you finish this document, you will know 99% of all things related to vPC. There are few things which are not covered there (routing over vpc, plus few newer features) but overall is the best starting point with vPC.

Cheers,

Sergiu