Description

This article describes the behavior where Border Gateway Protocol (BGP) neighborship may not come up between routers running Junos OS 13.3, 14.2, or 14.1 when Ethernet VPN (EVPN) family is configured.

Symptoms

BGP flaps were continually observed after upgrading from Junos OS 13.3 to 14.2. The following notification was received:

Jun 14 07:09:09 mx rpd[1686]: bgp_rcv_nlri:9264: NOTIFICATION sent to 30.30.30.1 (Internal AS 1): code 3 (Update Message Error) subcode 10 (bad address/prefix field), Reason: peer 30.30.30.1 (Internal AS 1) update included invalid route 3:0:0::0::/304 (26 of 28)
Jun 14 07:09:09 mx rpd[1686]: Received malformed update from 30.30.30.1 (Internal AS 1)
Jun 14 07:09:09 mx rpd[1686]: Family evpn, prefix 3:0:0::0::/224 Invalid

Solution

According to RFC 7432 section 7.3 (Inclusive Multicast Ethernet Tag Route) , Junos OS 13.3 incorrectly includes ESI in type 3 route which is incorrect as seen below.


Type 3 EVPN route advertised from a box running Junos OS 14.2: 

user@mx> show route advertising-protocol bgp 30.30.30.3 detail   

evpn1.evpn.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)  
* 3:15270:152016::0::30.30.30.2/304 (1 entry, 1 announced)  
BGP group bgp-m320-1 type Internal      
 Route Distinguisher: 15270:152016      
 Route Label: 299840   
 PMSI: Flags 0x0: Label 299840: Type INGRESS-REPLICATION 30.30.30.2   
 Nexthop: Self      
 Flags: Nexthop Change      
 Localpref: 100      
 AS path: [1] I      
 Communities: target:15270:152016      
 PMSI: Flags 0x0: Label 299840: Type INGRESS-REPLICATION 30.30.30.2

Type 3 route advertised from box running 13.3

user@mx > show route advertising-protocol bgp 30.30.30.3 detail

evpn1.evpn.0: 1 destinations, 2 routes (1 active, 0 holddown, 0 hidden)
* 3:15270:152016::0 ::0 ::30.30.30.1/384 (2 entries, 1 announced)
BGP group bgp-240-4 type Internal
  Route Distinguisher: 15270:152016
  Route Label: 314704
  PMSI: Flags 0x0: Label 314704: Type INGRESS-REPLICATION 30.30.30.1
  Nexthop: Self
  Flags: Nexthop Change
  Localpref: 100
  AS path: [1] I
  Communities: target:15270:152016
  PMSI: Flags 0x0: Label 314704: Type INGRESS-REPLICATION 30.30.30.1

This is the reason BGP keeps flapping with message "update included invalid route" if your box is running Junos 14.2 and the peer is running 13.3.

In a case with EVPN, use the same Junos OS version on the BGP peers. It is recommended to use Junos OS 14.2 or higher, which is up to the RFC standard.