I'm looking to implement a new network design with Juniper EX Series switches. Part of this involves implementing vPC between my core and ToR switches (and also between ToR and host).

The goal is to be able to split 4x1GE links into 2x2GE port groups, each one split between my two core switches for redundancy, and still obtain near 4 Gbps bandwidth to each rack.

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I'm fairly new to the concept of vPC but I don't seem to be able to find a Juniper equivalent for this technology - other than stacking the ToR switches with Virtual Chassis technology.

I'll probably end up using Virtual Chassis if I can't do it any other way, but I'd like to try and keep the ToR switches un-stacked, if I can.

The only other option I know of is to use MSTP to balance traffic per VLAN - which is probably OK given that we use 1xVLAN per customer and each host can do 2 Gbps max, but a port channel seems much simpler to configure and maintain.

Am I missing something?

3 Answers 3



If talking in Cisco terms, the main difference between vPC and basic stacking (StackWise, FlexStack) is excluding of splitbrain situation, when both members become a master and continue to forwarding.

Juniper EX series currently do not support any technology like vPC, so MLAG can be completed only with Virtual Chassis which can be splitbrained.

Although Juniper have an analog of vPC, greatly works on MX series routers. They calling it directly "MC-LAG", which additionally uses ICCP to communicating between MC-LAG nodes. Those technologies well discribed in the book "Juniper MX Series" by Douglas Richard Hanks, Jr. and Harry Reynolds.

  • Thanks for this. My main concern is that with VC the stack then shares processes and the config, which I feel would make it more vulnerable to config and software issues. Is there any way to use VC without actually doing stacking? I'm guessing not... But worth asking.
    – Geekman
    Dec 12, 2013 at 7:27
  • There are many differencies in MLAG protocols in compare with stacking and many of them are results of partially independent control planes. However those control planes of MLAG group nodes should at least know about each other thats why some configuration must be done.
    – Sk1f3r
    Dec 12, 2013 at 18:17
  • Again, in compare with Cisco Stacking, VC have many advantages, at least: 1) VC between different EX series switches - you can make create one logical device from 3 x 4200 and 2 x 8200 and 1 x 3200 (please check official compatability info); 2) any data port can be used as VC port, except some low level EX switches which can use only special VC ports or uplink ports as VC port; 3) distance between VC members limited only by power of SFP optical signal - up to 70km. As a result the scheme presented above can be amazing compact on L3.
    – Sk1f3r
    Dec 12, 2013 at 18:18

From EX9000 Series, Juniper does support MC-LAG


I believe VC port link aggregation should be an equivalent. https://www.juniper.net/documentation/en_US/junos/topics/concept/virtual-chassis-ex4200-aggregated-ethernet.html

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    Jan 15, 2019 at 7:41

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