Tag Archives: cisco systems

CCIE DC – 1.1.a Link Aggregation – Virtual Port Channel Example

CCIE Data Center, , , ,

This post examines a sample configuration of a virtual port channel. This port channel is created between two Nexus 7K systems and downstream Nexus 5K systems. This is part of the link aggregation section of the exam requirements in CCIE Data Center. Below is the diagram you can use for reference in this example. We will only demonstrate the config of a single VPC peer since the other peer is simply a mirror of this configuration.

Virtual Port Channel

Our previous post on this subject focused on the configuration steps. You can find it here: https://www.ajsnetworking.com/ccie-dc-1-1-a-link-aggregation-configure-virtual-port-channels/

The Configuration

First, we will prepare the vPC keepalive link for this scenario. Do not be thrown off by the name of our VRF. This configuration does not technically fall under the vPC config (yet!).

N7K-A# configure terminal
N7K-A(config)#  vrf context VPC-KEEPALIVE
N7K-A(config-vrf)# interface ethernet 3/18
N7K-A(config-if)# no switchport
N7K-A(config-if)# vrf member VPC-KEEPALIVE
Warning: Deleted all L3 config on interface Ethernet3/18
N7K-A(config-if)# ip addr 209.165.200.225/24

Next, we will configure the vPC domain (after enabling the feature of course) and configure the peer-keepalive link we prepped.

N7K-A(config)# feature vpc
N7K-A(config)# vpc domain 10
N7K-A(config-vpc-domain)# peer-keepalive destination 209.165.200.226 source 209.165.200.225 vrf VPC-KEEPALIVE

Now, we configure a port channel between our vPC peers and configure it as the vPC peer link.

N7K-A(config-vpc-domain)# interface ethernet 3/16-17
N7K-A(config-if)# channel-group 10
N7K-A(config-if)# interface port-channel 10
N7K-A(config-if)# vpc peer-link

Next, we will head down to the N5K and configure a “plain ole” LACP port channel.

N5K-A# config t
N5K-A(config)# feature lacp
N5K-A(config)# int e 1/1-2
N5K-A(config-if-range)# channel-group 201 mode active

Now, it is time to configure the vPC on the N7K.

N7K-A(config-if)# feature lacp
N7K-A(config)# interface e 3/21
N7K-A(config-if)# channel-group 201 mode active
N7K-A(config-if)# int port-channel 201
N7K-A(config-if)# vpc 201

The Verification

You should note that you can and should perform verifications as you go along here. For example, you can verify reachability, check the port channels that are configured, and watch the progress of the vPC as you configure it. For brevity here, we will just end this post and this example with our critical show vpc command.

N7K-A(config-if)# show vpc brief
Legend:
     (*) - local vPC is down, forwarding via vPC peer-link

vPC domain id                          : 10
Peer status                            : peer adjacency formed ok
vPC keep-alive status                  : peer is alive
Configuration consistency status       : success
Per-vlan consistency status            : success
Type-2 consistency status              : success
vPC role                               : secondary
Number of vPCs configured              : 1
Peer Gateway                           : Disabled
Dual-active excluded VLANs and BDs     : -
Graceful Consistency Check             : Enabled
Auto-recovery status                   : Enabled (timeout = 240 seconds)
Operational Layer3 Peer-router         : Disabled
Self-isolation                         : Disabled

vPC Peer-link status
--------------------------------------------------------------------------------
id Port Status  Active vlans Active BDs
-- ---- ------ -------------------------------------------------------------
1  Po10 up      1,12 -

vPC status
------------------------------------------------------
id     Port        Status Consistency  Active VLANs
----- ------------ ------ ----------- ----------------
201    Po201       up      success     1,12

For even more information – check out this Cisco documentation at https://www.cisco.com/c/en/us/products/collateral/switches/nexus-5000-series-switches/design_guide_c07-625857.html
Pearson Education (InformIT)

CCIE DC – 1.1.a Link Aggregation – Configure Virtual Port Channels

CCIE Data Center, ,

This post examines the limitations you should be aware of when configuring virtual port channels. It also examines the configuration steps. This is part of the link aggregation section of the exam requirements in CCIE Data Center.
Aggregation

Our previous post on this subject focused on the control plane. You can find it here: https://www.ajsnetworking.com/ccie-dc-written-1-1/

Limitations

Before you dive right into the configuration steps, you should be aware of the limitations when it comes to your virtual port channels. These include:

  • In the “standard” virtual port channel – you use exactly two vPC peer switches – no more than that are supported. A later post here will cover the extended vPC technology, but this post does not consider that.
  • It is not possible for one of your peer vPC devices to participate in more than one vPC.
  • All ports for a given vPC must exist in the same VDC (Virtual Device Context). You cannot span a vPC across multiple VDCs.
  • A 10 Gbps link is required for the vPC peer link. Typically, you should use at least two links in a port channel for this component.
  • A vPC is a Layer 2 construct. There is no support for the creation of Layer 3 vPCs.

The Configuration Steps

As you might guess, you should double-check all of your physical connections before launching into the vPC configuration. Ensure that your physical link(s) for the peer link are in place and healthy. Also, keep in mind that you make these configurations on each of the vPC peer devices.

Step 1. First, you must enable the vPC feature – you do this with the command: feature vpc

Step 2. Create the vPC using the vpc domain <domain_id> command

Step 3. Next, specify your peer keepalive link – this link can be in any VRF (including Management); use the command – peer-keepalive destination <remote_peer_ip> source <local_peer_ip> vrf <vrf_name>

Step 4. Configure your peer link. This is typically done with a port channel (as described above) as follows:

interface port-channel <port_channel_id>
switchport mode trunk
vpc peer-link

Step 5. Configure a port channel that leads to the downstream device; use the command vpc <domain_id> under the port channel

In the next post, I will walk you through a configuration on live equipment. We will also walk through the important vPC verifications you would want to perform at that time. As always, thanks for reading.

For even more information – check out this Cisco documentation at https://www.cisco.com/c/en/us/products/collateral/switches/nexus-5000-series-switches/design_guide_c07-625857.html
Pearson Education (InformIT)