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

[Nikolas Geyer]

Yes, I have experience with multiple layers of back-to-back MC-LAG as you are describing with a similar product set, EX9200 (basically an MX) as core and QFX5k as aggregation and access.

It worked “ok” for the most part however, we were pushing numbers on this setup beyond what 99% of customers ever would which meant we got to experience the weird and wonderful failures, mostly related to memory leaking or buffer exhaustion (and when it went bang it REALLY went bang).

In 2018 I couldn’t in good faith advocate this back-to-back MC-LAG over multiple tiers setup to anyone. If you need L2 adjacency between your access switches then stitch it up using EVPN on your QFX’s. 

Nik.

Sent from my iPhone

> On 13 Mar 2018, at 12:21 pm, Karl Gerhard <karl_gerh at gmx.at> 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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