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I am posting this question to get better understand of VRF on Nexus switch.

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This is the scenario i have 10G_A link from my ISP running BGP on it, now i need more capacity so order second 10G_B link with new handoff and new Public IP pool and terminate on same Nexus switch in that case i should use VRF right? to isolate both link routing.

Or i am missing something to understand VRF?

EDIT

My goal is how do i handle two handoff link from ISP with different class-C subnet and how do i route traffic for Subnet-A goes to 10G_A and Subnet-B goes to 10G_B link?

If it's not possible with VRF then what would be the best solution here?

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    It depends. How do you intend to balance the traffic among the two links? Are both links to the same ISP? Do you advertise your own IP range? (you speak about a new public IP pool...).
    – JFL
    Jan 16, 2018 at 21:03
  • Both link from same ISP and I’m planning to run BGP on both link and both link have own public IP range.
    – Satish
    Jan 16, 2018 at 23:40
  • We don't want to load balancer traffic, all I need isolation of traffic.
    – Satish
    Jan 17, 2018 at 1:16
  • Can you add more detail?What is the incoming traffic? How do you segregate which traffic use which link? As explained by @mxrx with VRF you basically get two routers in a single box.
    – JFL
    Jan 17, 2018 at 8:48
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin ♦
    Apr 1, 2018 at 19:53

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If your goal is isolation of traffic then you'd have downstream ports on the switch that would be in VRF's A or B and then configure routing within the respective vrf's (either BGP or just a static default). You'd use different IP ranges in the two vrf's as, ultimately, the Internet is one routing table and has no way to differentiate between identical IP's across your vrf's.

I'm inferring a bit but I don't think vrf's are the tool to accomplish your stated goal of adding capacity. VRF's are fundamentally about segmentation - so in the example above, the switch would be logically split into two distinct operational units. You'd much more typically just hook up the second connection to the same vrf, add it to BGP, advertise the same routes and then potentially adjust policy to shift some traffic to the new line (...this may not be necessary depending on which carriers and what views you're receiving).

If this isn't the case then, again, two vrf's with their own sets of interfaces and routes and you're all set. Logically (at least from a routing perspective) it's basically behaving like two independent switches.

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  • I have update my question, i want to send Subnet-A traffic over link A and Subnet-B traffic over link B, i thought it is easy with VRF that is why i raise that question, as you said we can do this using BGP subnet advertisement on individual link in that case that would be good idea too but just wanted to understand how many option i have
    – Satish
    Jan 18, 2018 at 3:10
  • Controlling the inbound traffic is pretty straightforward - advertise subnet A out link A and subnet B out link B and traffic will find itself to the right place. Outbound traffic is a bit trickier. The multi-vrf approach could work, as could policy based routing (PBR) where you'd match on traffic from subnet A that isn't bound to anything local and set its next-hop to ISP A and vice-versa for subnet-B.
    – rnxrx
    Jan 18, 2018 at 3:42
  • I am worry PBR will overkill my CPU, currently we have 10G traffic but in 6 month it will be 40G possible.
    – Satish
    Jan 18, 2018 at 15:57
  • If PBR runs on a given Nexus switch then it's supported in hardware and can run at line rate without much (or any) CPU impact.
    – rnxrx
    Jan 18, 2018 at 18:18

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