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StubArea51
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RouterOSv7 first look – MLAG on CRS 3xx switches

Sat Jun 05, 2021 4:43 pm

Did some testing with the new MLAG feature and wrote a blog post on it.

https://stubarea51.net/2021/06/04/mikro ... -switches/

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Re: RouterOSv7 first look – MLAG on CRS 3xx switches

Sun Jun 06, 2021 6:21 am

Nice work on the article Kevin.
 
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Re: RouterOSv7 first look – MLAG on CRS 3xx switches

Sun Jun 06, 2021 1:20 pm

I heard the peerlink is a single point of failure in an MLAG pair
What's the best way to hook up four racks each with two ToR CRS326Q?
Each rack of course consists of servers with LAG connection to their ToR switches.
 
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anav
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Re: RouterOSv7 first look – MLAG on CRS 3xx switches

Sun Jun 06, 2021 2:40 pm

I have no idea what that does but your input and work are incredible!!
All that talent in MS, but really its too hot or too wet or to windy(tornadoes), why dont you move up to the promised land (Canada).
 
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Re: RouterOSv7 first look – MLAG on CRS 3xx switches

Sun Jun 06, 2021 8:45 pm

Nice article. I noticed MLAG requires STP/RSTP. We have that disabled in most of our switches. We have a switch-centric setup and layer3 ring in our core and couldn't make it work with STP enabled. Might have been because I wasn't smart/patient enough to make MSTP work. But I also thought a complex MSTP config defies the KISS principle.
 
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netravnen
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Re: RouterOSv7 first look – MLAG on CRS 3xx switches

Mon Jun 07, 2021 12:26 am

Did some testing with the new MLAG feature and wrote a blog post on it.
Have you considered e.g. using a GRE tunnel interface as the peer-port to be able to ensure IP multi-path redundancy in your test topology? Thereby avoiding relying on the physical peer interface not being interrupted during normal operations. (e.g. cable unplugged by accident, optic/port hw failure)

Some networks will use MLAG for geo distant (<50km) devices with e.g. L2 Network-to-Network Interconnects (e.g. 2x1x10 GE, 1x10 GE NNI per router, in an active-standby set-up). An example for this could be two service providers, where provider a uses provider b's access net to reach customers. With the set-up being provider b backhauls all traffic as L2 circuits to a geo-redundant L2 NNI between provider a and b's networks in two different datacentres.
 
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Re: RouterOSv7 first look – MLAG on CRS 3xx switches

Mon Jun 07, 2021 1:23 am

Have you considered e.g. using a GRE tunnel interface as the peer-port to be able to ensure IP multi-path redundancy in your test topology? Thereby avoiding relying on the physical peer interface not being interrupted during normal operations. (e.g. cable unplugged by accident, optic/port hw failure)

Some networks will use MLAG for geo distant (<50km) devices with e.g. L2 Network-to-Network Interconnects (e.g. 2x1x10 GE, 1x10 GE NNI per router, in an active-standby set-up). An example for this could be two service providers, where provider a uses provider b's access net to reach customers. With the set-up being provider b backhauls all traffic as L2 circuits to a geo-redundant L2 NNI between provider a and b's networks in two different datacentres.
A few things to unpack here:

1) MikroTik's peer port for MLAG is not IP based, it runs at L2

2) Only physical interfaces can be selected - see below:

[admin@CSW-01] > interface/bridge/mlag/set peer-port=gre-tunnel1
invalid value for argument peer-port:
    input does not match any value of interface
    input does not match any value of interface-bond

3) For geographically diverse L2 transport, I prefer VPLS within the scope of MikroTik equipment and would tie the VLAN transport over a pseudowire into MLAG endpoints (if needed for HW redundancy to the CE)
 
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Re: RouterOSv7 first look – MLAG on CRS 3xx switches

Mon Jun 07, 2021 6:40 am

One thing I noticed is that the documentation says "The MLAG requires enabled STP or RSTP protocol" - does MLAG not work with MSTP?
 
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Re: RouterOSv7 first look – MLAG on CRS 3xx switches

Tue Jun 08, 2021 3:12 am

One thing I noticed is that the documentation says "The MLAG requires enabled STP or RSTP protocol" - does MLAG not work with MSTP?

I just tried using MSTP on the Bridge the MLAG ports are on, it definitely does not support that version of STP.

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Re: RouterOSv7 first look – MLAG on CRS 3xx switches

Tue Jun 08, 2021 4:00 am

I just tried using MSTP on the Bridge the MLAG ports are on, it definitely does not support that version of STP.
That seems an odd limitation.. I would hope that this is just a temporary state of affairs and that MLAG will support MSTP later.
 
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Re: RouterOSv7 first look – MLAG on CRS 3xx switches

Tue Nov 16, 2021 5:06 pm

The links on the picture are marked as Active and Backup. Is that true?

Since there is no "max active links" option in RouterOS, mode=802.3ad should means load balancing over all links.
 
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Re: RouterOSv7 first look – MLAG on CRS 3xx switches

Mon Dec 20, 2021 5:49 pm

Can you test MLAG only with physical gear? I tried to test it using an CHR image in Eve-NG, but the command "/interface bridge mlag" is missing (with a RouterOS 7.1 image).

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