Hi ..
i am getting problem to up eBGP in between MikroTik and Juniper ..

Following debug found at Mikrotik side..
Error : Unsupported capability received, code: 128
Log:
bgp1-1 {l_addr: 10.200.241.162, r_addr: 10.200.241.161} Starter {openOk: false} Unsupported capability received, code: 128

what does mean "Unsupported capability received, code: 128 "?

MikroTik OS version : 7.13

Mik bgp debug logs is attached

Anyone help to solving this problem above mentioned issue ?

The full list of BGP capability codes are available here: https://www.iana.org/assignments/capabi ... odes.xhtml

what does mean "Unsupported capability received, code: 128 "?

Exactly what the capability codes is.

MikroTik ROS does not (yet) support capability code 128 (Prestandard Route Refresh (deprecated)).

Try disabling the capability on the remote peer.

BGP Capability Code 128 is deprecated. Read this:
https://www.rfc-editor.org/rfc/rfc8810.html

Ask Juniper TAC to read it too. Juniper is at fault here, they should remove code 128 features fully.

Juniper has bad history with BGP safety measures:
https://blog.benjojo.co.uk/post/bgp-pat ... r-handling
https://labs.ripe.net/author/emileaben/ ... n-routing/
https://blog.apnic.net/2023/04/13/navig ... r-routers/

BGP Capability Code 128 is deprecated. Read this:
https://www.rfc-editor.org/rfc/rfc8810.html

Ask Juniper TAC to read it too. Juniper is at fault here, they should remove code 128 features fully.

Juniper has bad history with BGP safety measures:
https://blog.benjojo.co.uk/post/bgp-pat ... r-handling
https://labs.ripe.net/author/emileaben/ ... n-routing/
https://blog.apnic.net/2023/04/13/navig ... r-routers/

Thanks you for shared those links...

BTW it is not an error, it is a debug message informing that unsupported apability is being sent by remote peer, thats it. the BGP session will work regardless of that message.

There is another reason why BGP session is tearing down which happens after open messages are exchanged and enteing established state, remote device sends a notify message that it will close the session, see juniper logs why or check notify message content for more info.