This KB describes the log message "Received 6 malformed attribute ELC."
Below logs may be seen on the router.We observe that the BGP peers are sending packets with malformed ELC attribute.
Aug 13 07:26:20.095 2024 rtr rpd[10735]: %DAEMON-3: Total incoming malformed attributes from x.x.x.x (Internal AS 1234) since last logging
Aug 13 07:26:20.096 2024 rtr rpd[10735]: %DAEMON-3: Received 2 malformed attribute ELC(28)
Aug 13 07:26:20.096 2024 rtr rpd[10735]: %DAEMON-3: Total incoming malformed attributes from x.x.x.x (Internal AS 1234) since last logging
Entropy Label Capability attribute (ELC) is an optional, transitive BGP path attribute that can be used to inform an LSP ingress router about an LSP egress router's ability to process entropy labels.
We should not see the bgp peerings to have flapped due to this malformed packets. Hence these malformed packets should not cause any service impact.However, we can recommend customer to configure the bgp-error-tolerance
Please note that when we configure "bgp-error-tolerance" it should not cause the BGP sessions to go down nor traffic being dropped so this is a non-impacting configuration change.
Below is the document which explains bgp-error-tolerance.
https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-error-messages.html
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Starting in Junos OS Release 23.4R1, we use the Entropy Label Capability (ELCv3) attribute defined within the IETF BGP Next-Hop Dependent Capability Attribute for load balancing. This attribute replaces the existing ELCv2 attribute.
To operate the ELCv2 attribute along with ELCv3, explicitly configure the elc-v2-compatible statement at the [edit protocols bgp family inet labeled-unicast entropy-label] hierarchy level.
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Make sure bgp-error-tolerance is configured when upgrading networks with labeled-unicast to 23.4.
Starting in Junos OS Release 24.2R1, BGP error handling is enabled by default
2024-08-20 : Article Created
2025-07-12 : Added additional info as in comments.