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I just put up a LACP between two Cisco SG-200 switches.

Unfortunately some PCs connected to these switches got problems like lost Postgres connections etc.

My configuration is simple:

----------------             ----------------
|   switch_1   | =========== |   switch_2   |
|              | =========== |              |
----------------             ----------------

LAG ports: GE45, GE46, GE47, GE48 on both switches
Load Balance Algorithm: IP/MAC Address

Postgresql show logs:

could not receive data from client: Connection reset by peer

My LACP config: imgur.com/a/4yfAzOV

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What could be the reason?

Stuggi
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Knowledge
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  • Does it work if you disconnect all but one link? – Stuggi Aug 13 '20 at 06:54
  • You mean disconnect LAG patch cords except one? – Knowledge Aug 13 '20 at 06:58
  • Exactly, that should basically force the LAG to use only one port, effectively removing the LAG without any configuration changes, and shows you if the issue is the balancing algorithm used or something else. – Stuggi Aug 13 '20 at 07:13
  • Disconnected all LAG cables, except 1. In general, is the use of port aggregation for a switch connection correct? – Knowledge Aug 13 '20 at 07:19
  • Ok, did it affect how things work? Port aggregation is quite common in enterprise networks between for example two large switches where you need all the link capacity. If you just want redundancy, Spanning Tree is usually used. – Stuggi Aug 13 '20 at 08:52
  • The logs are empty and everything looks stable. Any idea why LACP not working correctly? – Knowledge Aug 13 '20 at 08:53
  • Another thing to keep in mind when using LAGs is how the traffic is balanced, if you have a lot of clients talking to a single server, you want to balance according to the MAC address of the sender, because if you balance according to the destination, all traffic will go through one of the links and the other ones won't get used. – Stuggi Aug 13 '20 at 08:53
  • So i try to change balance algorithm from IP/MAC Address to MAC Address but probably I tried to change it before - without result. – Knowledge Aug 13 '20 at 09:15

1 Answers1

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Did you setup Switch 1 in LACP Passive and Swtich 2 in LACP Active (or vice-versa)? If you have both switchs in ACTIVE mode they will both try to negotiate the LACP and that can cause you some problems. (not sure if these settings are configurable on a SG200). If possible share your LAG/LACP configurations with us.

NBorba
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