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Ask the Expert: Different Flavors and Design with vPC on Cisco Nexus 5000 Series Switches

Welcome to the Cisco® Support Community Ask the Expert conversation.  This is an opportunity to learn and ask questions about Cisco® NX-OS.

The biggest limitation to a classic port channel communication is that the port channel operates only between two devices. To overcome this limitation, Cisco NX-OS has a technology called virtual port channel (vPC). A pair of switches acting as a vPC peer endpoint looks like a single logical entity to port channel attached devices. The two devices that act as the logical port channel endpoint are actually two separate devices. This setup has the benefits of hardware redundancy combined with the benefits offered by a port channel, for example, loop management.

vPC technology is the main factor for success of Cisco Nexus® data center switches such as the Cisco Nexus 5000 Series, Nexus 7000 Series, and Nexus 2000 Series Switches.

This event is focused on discussing all possible types of vPC along-with best practices, failure scenarios, Cisco Technical Assistance Center (TAC) recommendations and troubleshooting

Cisco Experts

Vishal Mehta is a customer support engineer for the Cisco Data Center Server Virtualization Technical Assistance Center (TAC) team based in San Jose, California. He has been working in TAC for the past 3 years with a primary focus on data center technologies, such as the Cisco Nexus 5000 Series Switches, Cisco Unified Computing System™ (Cisco UCS®), Cisco Nexus 1000V Switch, and virtualization. He presented at Cisco Live in Orlando 2013 and will present at Cisco Live Milan 2014 (BRKCOM-3003, BRKDCT-3444, and LABDCT-2333). He holds a master’s degree from Rutgers University in electrical and computer engineering and has CCIE® certification (number 37139) in routing and switching, and service provider.

Nimit Pathak is a customer support engineer for the Cisco Data Center Server Virtualization TAC team based in San Jose, California, with primary focus on data center technologies, such as Cisco UCS, the Cisco Nexus 1000v Switch, and virtualization. Nimit holds a master's degree in electrical engineering from Bridgeport University, has CCNA® and CCNP® Nimit is also working on a Cisco data center CCIE® certification While also pursuing an MBA degree from Santa Clara University.

Remember to use the rating system to let Vishal and Nimit know if you have received an adequate response. 

Because of the volume expected during this event, Vishal and Nimit might not be able to answer every question. Remember that you can continue the conversation in the Network Infrastructure Community, under the subcommunity LAN, Switching & Routing, shortly after the event. This event lasts through August 29, 2014. Visit this forum often to view responses to your questions and the questions of other Cisco Support Community members.

  • LAN Switching and Routing
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I know this is for the Nexus

I know this is for the Nexus 5000 but information is easy to find for this. Are there any up to date design guides for the Nexus 7000 and 2000 for VPC along with supported server connectivity? I find this information a bit hard to find, if you can provide any I would appreciate it, thanks.

16 REPLIES

Good time-of-day.We have a

Good time-of-day.

We have a couple of Nexus 5000 switches in vPC, configured with peer-gateway, but without peer-switch; running as first-hop (with HSRP) for 50 end-user VLANs.

Could you please hint what should be the correct steps to minimize service disruption (in terms of routing and STP), if we need to reload holder of primary vPC role?!

Thanks.

New Member

Hi Vasilii,to answer your

Hi Vasilii,

to answer your question.

The “vpc peer-gateway” allows HSRP routers to accept frames destined for their vPC peers.  This feature extends the virtual MAC address functionality to the paired router’s MAC address.  

In addition vPC  the peer-switch feature reduces convergence time as a result of a spanning-tree failure from 3 seconds to sub-second. so if you dont have the peer-switch option then you 3 second spt convergence time.

-Nimit

 

Hello VasiliiIs your Primary

Hello Vasilii

Is your Primary vPC N5k switch root of Spanning-Tree ?

If so then Peer-Switch would help to minimize the disruption to just sub-seconds as explained by Nimit.

Please see below link (search for Peer-Switch) for explanation on how Peer-Switch configuration can help

http://www.cisco.com/c/en/us/products/collateral/switches/nexus-5000-series-switches/design_guide_c07-625857.html#_Toc271759470

Otherwise if these Nexus 5000 are not roots then rebooting Primary N5k will not cause service disruption as Secondary N5k will continue to forward the traffic.

To summarize below are the options:

1. if N5k are not root....then reboot of primary N5k should not have traffic loss
2. if they are the root then better to configure peer-switch
3. if peer-switch cannot be configured and N5k are the roots, then 3 second outage expected

Let me know if more clarification is needed.

Thanks

Vishal

Thank you for reply.The vPC

Thank you for reply.

The vPC is a root bridge for all VLANs, but peer-switch is not configured (clear about this - STP convergance should happen).

Won't the reload of vPC primary device disrupt the service for any significant time? Running firmware is 5.3.1 and my question is about proofed behavior of vPC if we reload operational primary (like, does peer-keepalive and peer-links go down simultaneously?)

Upon reboot of Primary vPC

Upon reboot of Primary vPC switch there will not be any traffic loss on vPC links as secondary vPC switch will become primary and forward the traffic. i.e There is no impact on north/south data traffic but east-west traffic over Peer-Link will be lost (black-holed) during reboot time of primary vPC switch

During reboot yes both Peer-Link and Keepalive link will go down simultaneously.

The details on expectation during vPC peer switch reboot are explained at link below:

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/operations/n5k_vpc_ops.html#wp425292

Let me know if further clarification is needed.

Regards,

Vishal

I know this is for the Nexus

I know this is for the Nexus 5000 but information is easy to find for this. Are there any up to date design guides for the Nexus 7000 and 2000 for VPC along with supported server connectivity? I find this information a bit hard to find, if you can provide any I would appreciate it, thanks.

New Member

Hi,Host–to–Cisco Nexus 2000

Hi,

Host–to–Cisco Nexus 2000 Series Connectivity Options
A host can connect to a Cisco Nexus 2000 using all the most common technologies
like network interface card (NIC) teaming or MAC pinning (active-active uplinks using
the Cisco Nexus 1000V Switch, for example) or port channels. On the top of those,
the Nexus 2000 supports the Virtual Port Channel (vPC) functionality, a unique Cisco
feature that allows hosts to attach to a pair of Cisco Nexus 2000 with active/active
redundancy based on standard port channeling.

please find the attached for your reference.

i hope this help !!

 

let me know if you have any additioanl questions.

 

Hello KWillacey,Yes there is

Hello KWillacey,

Yes there is Server deisgn guide with Nexus 7000 but it is specific for UCS-B chassis.

The recommendations listed below will be helpful in connecting any other servers with Nexus 7000

http://www.cisco.com/c/en/us/products/collateral/switches/nexus-7000-series-switches/white_paper_c11-623265.html

 

Please refer above link and feel free to ask us any follow-up questions

Thanks,

Vishal

Thanks for the information

Thanks for the information guys. I will review and ask any follow up questions.

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