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VPC pair of Nexus 7K and servers connected directly

Hi all,

I hope you can help me, i want to know if is possible to do the follow escenary:

My Data Center has one single core switch where is connected several servers, one port is the link to the router wan and other port is the link to the FW, my boss wants to install 2 nexus in order to replace the single switch. All my network has only one address, for example 192.168.10.0/24

if I connect two nexus 7010 in VPC and Domain, each nexus is going to has 2 modules with 48 port 10/100/1000 rj45 and i wan to connect servers directly to each nexus, with this figure i'm going to have a group of servers connected in two different nexus, Do they can have the same network 192.168.10.0/24 considering that the nexus are in the same vdc and vlan and have only one gateway for both groups????? If the answer is positive, which nexus would be the gateway for that address, the primary or secondary???? Or i must have a different address for both group of servers, i mean for example 192.168.10.0/24 and 192.168.12.0/24??? thus each nexus would be the gateway for that new address???

To have two nexus connected by VPC in a Domain mean that one computer connected to one nexus can share the same address or vlan with other computer connected to the other nexus????

Any imput is going to help me in order to have a better idea!!! Thanks a lot.

2 REPLIES
Silver

VPC pair of Nexus 7K and servers connected directly

csco10851302 wrote:

Hi all,

I hope you can help me, i want to know if is possible to do the follow escenary:

My Data Center has one single core switch where is connected several servers, one port is the link to the router wan and other port is the link to the FW, my boss wants to install 2 nexus in order to replace the single switch. All my network has only one address, for example 192.168.10.0/24

if I connect two nexus 7010 in VPC and Domain, each nexus is going to has 2 modules with 48 port 10/100/1000 rj45 and i wan to connect servers directly to each nexus, with this figure i'm going to have a group of servers connected in two different nexus, Do they can have the same network 192.168.10.0/24 considering that the nexus are in the same vdc and vlan and have only one gateway for both groups????? If the answer is positive, which nexus would be the gateway for that address, the primary or secondary???? Or i must have a different address for both group of servers, i mean for example 192.168.10.0/24 and 192.168.12.0/24??? thus each nexus would be the gateway for that new address???

To have two nexus connected by VPC in a Domain mean that one computer connected to one nexus can share the same address or vlan with other computer connected to the other nexus????

Any imput is going to help me in order to have a better idea!!! Thanks a lot.

If you run the two Nexus switches connected with vPC's between them, then you can create HSRP across the SVI's for your VLAN and connect directly to the line card.

My question is *why* do you want vPC's running? The main use for vPC's is to provide redundancy for multi-homed devices by allowing a "virtual" etherchannel to be created - giving you the benefits of etherchannel (load balancing, additional bandwidth) and the redundancy of having the etherchannel spanned across physically separate switches - so if one Nexus fails, the other keeps going and you have effectively *no* loss owing to spanning tree - in my tests I think I lost *one* packet across a vPC link at 10 Gb/s when I disconnected the primary switch.

If your servers are all single homed, you're probably much better off just running a normal port-channel between the two Nexus switches, trunking all the VLAN's across this port-channel link, and creating SVI's on each Nexus then using HSRP (or VRRP) to provide redundancy groups for routing.

The only reason I can see for setting up vPC's if you're conencting single-homed devices is to future proof - on the possibilioty that you *may*, in the future, connect multi-homed devices across your two Nexus switches - in this case, get the vPC setup ready and just don't use it. You still create an SVI for the VLAN on each Nexus and run HSRP between them.

This way, you can run a single subnet per VLAN across both Nexus switches and have your servers in the one range - 192.168.10.0/24 - but you need *three* addresses for the routers (one for Nexus one, one for Nexus two, and one for the HSRP group) instead of just one - but you will have redundancy for routing if one Nexus should fail - at least the devices on the second Nexus will keep routing without issue.

For what it's worth, I think a pair Nexus 7010's is a *massive* overkill for what you're describing - if you're only connecting servers, you could do it much cheaper with a pair of 4503 switches, a suitable 10 gig supervisor engine (for the trunk between the switches) and a couple of 48 port 10/100/100 line cards. But if your boss has money to spare, don't argue with him - spend it. :-)

Cheers.

New Member

Re: VPC pair of Nexus 7K and servers connected directly

HI Darren, thanks a lot for your time in responding my doubts and you're rigth...wtih 2 cisco 4503 is enough. According your reply:

If you run the two Nexus switches connected with vPC's between them,  then you can create HSRP across the SVI's for your VLAN and connect  directly to the line card.

DO i need my old switch connected between the nexus??? Should i remove the old switch that nowadays has my servers??? Do you have any document or example about this. I would like to see the picture.

If your servers are all single homed, you're probably much better off  just running a normal port-channel between the two Nexus switches,  trunking all the VLAN's across this port-channel link, and creating  SVI's on each Nexus then using HSRP (or VRRP) to provide redundancy  groups for routing

Do you have any example configuration or graphics about this???

I have in mind some option about my network, i'm going to appreciate your comments i attached the images where shows some options.



thanks Darren for your help!!!!

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