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I just want to know if it's possible to implement mLACP (with VSS) or vPC on L3 interfaces. I just can't find any answer to this on cisco doc.

Thanks,

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    You can have layer-3 port channels. A link failure in a layer-3 port channel fails over much faster than even a routing protocol. – Ron Maupin Jan 2 '17 at 16:02
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(m)LACP and vPC are Layer 2 technologies, thus they don't apply to layer 3 interfaces

At layer 3 you use for example VRRP (to provide gateway to hosts) or routing protocols (like OSPF) to achieve redundancy and automatic switchover.

  • thank you for the help, thought I could save some IP with that – Jey10 Jan 2 '17 at 9:44
  • Newer NXOS versions on 7K and 9K definitely support L3 VPC's now (i.e. running a routing protocol over SVI's carried over VPC links). The typical use-case is running a dynamic routing protocol to a firewall but it can be used in most topologies. – rnxrx Jan 3 '17 at 0:36
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Yes, you can absolutely. You can setup a Port-Channel interface and set it with an IP. This is referred to as a Layer 3 port-channel and you can run routing protocols over it as needed. This will work regardless of if you are running this directly on the same switch or over a mLACP/ vPC.

int po1
description Uplink 
ip address 10.0.1.1 255.255.255.0 
no switchport

int gi1/1/2
no switchport    (--- important that all interfaces are in layer 3
channel-group 1 mode active

int eth2/1/2
no switchport    (--- important that all interfaces are in layer 3
channel-group 1 mode active

This would be a very bare bones example.

  • This is true on the downstream switch and in the case of VSS on a pair of C6K's but is not necessarily true on platforms supporting VPC (NXOS boxes - 7K, 5K, 9K, etc). Some support this functionality in recent code versions but require additional explicit configuration while others don't support it at all. There are also a bunch of caveats in terms of which protocols are supported as well as questions of protocol configuration, behavior of multicast, etc. – rnxrx Jan 3 '17 at 0:38

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