[j-nsp] Experience with two-tier MC-LAG?

[Karl Gerhard]

Hello

Layer 3 is only at the core (MX), aggregation (QFX) and access (EX) are layer 2 only.
So the MC-LAG between the QFX would be a layer 2 MC-LAG, while the MC-LAG between the MX is a Layer 3 MC-LAG with IRB. In this specific datacenter it's mostly servers that are connected to the access switches.

VXLAN and EVPN would add a ton of complexity to this setup, which is - at least at the moment, with only one MC-LAG - a very simple and easy to maintain network design.

Thanks for the replies so far.

Regards
Karl

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*From:* Brant Ian Stevens [mailto:branto at argentiumsolutions.com]
*Sent:* Tuesday, Mar 13, 2018 11:51 PM CET
*To:* Karl Gerhard
*Subject:* [j-nsp] Experience with two-tier MC-LAG?

> Do you have a layer-2 adjacency requirement at the edge? Even if you do, I'd ask why don't you use VXLAN and EVPN?
>
> On 3/13/18 12:20 PM, Karl Gerhard wrote:
>
>> Hello
>>
>> I would like to know whether anyone has deployed a two-tier MC-LAG:
>> MC-LAG #1 between the aggregation switches
>> MC-LAG #2 between the core routers
>> This would allow for a network design with "active/active everything".
>>
>> Our current setup is the following: Access (Juniper EX), Aggregation (Juniper QFX), Core (Juniper MX).
>> Our access switches use Redundant Trunk Groups to connect to two aggregation switches.
>> Each aggregation switch has an AE where the first cable of the AE goes the MX #1 and the second cable of the AE goes to MX #2. To make this possible we have an MC-LAG between the MXs.
>> Pic: https://abload.de/img/single-mc-lag2io7w.jpg
>> With this setup only one uplink of the access switch is utilized, the other one is idle due to the nature of redundant trunk groups (active/passive).
>>
>> If we had a second MC-LAG between the QFXs we could utilize both uplinks of the access switch.
>> Pic: https://abload.de/img/double-mc-lag4ppfd.jpg
>>
>> Does anyone have experience with such a setup? Is this the highway to debugging hell or is it a good idea that increases bandwidth available to the access layer?
>>
>> Regards
>> Karl
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>