Single-sided vs double-sided vpc

[Pulkit Nagpal]

• Introduction
• Description
• Network Diagram
• Pros and Cons
• Related Information

Introduction

This document describes what single-sided and double-sided vPCs are and also discuss their pros and cons.

Description

There are two main topologies available for deploying Nexus 5000 in access layer and Nexus 7000 in aggregation-layer. These are:

1. Single-sided vPC: In single-sided vPCs, each Nexus 5000 switch connects to a pair of Nexus 7000 aggregation switches using a unique vPC, but the Nexus 5000 switches do not run vPC themselves. Each access switch sees its uplink as a simple port-channel, and has no knowledge of vPC.
2. Double-sided vPC: In double-sided vPC both the Nexus 7000 and Nexus 5000 switches run vPC. Each vPC pair of Nexus 5000 switches is connected to the aggregation vPC pair using a unique vPC.

Network Diagram

Single-sided vPC:

Double-sided vPC:

Pros and Cons

	Single-Sided vPC	Double-Sided vPC
Pros	Simple topology with consistent, predictable traffic flows to and from servers.	Supports vPC connection to servers, enabling resiience and load-sharing over multiple NICs. Supports active/active. vPC peer-link provides extra resilience.
Cons	No capability for vPC to server. Resilient server connection options are limited to active/standby NIC teaming or transmit load-balancing.	Sub-optimal path for 50% of traffic to non-vPC-attached servers. All multicast traffic is copied across vPC peer-link, which can become a bottleneck in high-volume multicast cases.

Related Information

• Virtual Port channel quick configuration guide
• vPC: Building Networks without sponning tree protocol

[anonybird1]

Hi there,

I have a question.

In case of dual sided vPC, why do you configure a single vPC (vPC1 in the diagram) from N5Ks to N7Ks for all four links?

Why not to have two separate vPCs from access N5Ks to upstream aggregation N7Ks and still run vPC on N5Ks for downstream servers?

Thanks

[dvag-nsafe]

Hi pnagpal  ,

the vPC-ID's on the Cores (upper Switch piar) and the access (lower Switch pair) can be different, correct? Like, the N7K's would have vPC1 and the N5K would have vPC2. It'll still work right?

I ask because we have this configuration running at the moment and it seems to work.

[marinogr]

Hi,

We have a N5K in VPC and a Data link to carry nonVPC vlan. We want to migrate to new N9K VPC  suppose to double-side VPC.

For VPC Vlan is all clear per design double-side VPC.

How is trafffic carried of nonVPC data to new N9K VPC.  How to migrate nonVPC vlan to new N9K. We dont want to use data link in N9K.

I have not found this design or best practice or something for explanation.