Description

Topology : 
EX4300 [ge-0/0/23]<-->[ge-0/0/23]EX4200[xe-0/1/0]<--> [xe-0/0/47]QFX5110
Lab device configurations:

On EX4300: 
set interfaces ge-0/0/23 vlan-tagging
set interfaces ge-0/0/23 mtu 8000
set interfaces ge-0/0/23 unit 943 vlan-id 943
set interfaces ge-0/0/23 unit 943 family inet mtu 7500
set interfaces ge-0/0/23 unit 943 family inet address 10.19.43.1/30
set protocols ospf area 0.0.0.0 interface ge-0/0/23.943 metric 1000
set protocols ospf area 0.0.0.0 interface ge-0/0/23.943 bfd-liveness-detection minimum-interval 1000
set protocols ospf area 0.0.0.0 interface ge-0/0/23.943 bfd-liveness-detection minimum-receive-interval 1000
set protocols ospf area 0.0.0.0 interface ge-0/0/23.943 bfd-liveness-detection multiplier 3
set protocols ospf area 0.0.0.0 interface ge-0/0/23.943 strict-bfd
set protocols ospf area 0.0.0.0 interface ge-0/0/23.944 metric 1000
set protocols ospf area 0.0.0.0 interface ge-0/0/23.944 bfd-liveness-detection minimum-interval 1000
set protocols ospf area 0.0.0.0 interface ge-0/0/23.944 bfd-liveness-detection minimum-receive-interval 1000
set protocols ospf area 0.0.0.0 interface ge-0/0/23.944 bfd-liveness-detection multiplier 3

On EX4200: 

set interfaces interface-range telenet-clic member ge-0/0/23
set interfaces interface-range telenet-clic member xe-0/1/0
set interfaces interface-range telenet-clic mtu 9216
set interfaces interface-range telenet-clic unit 0 family ethernet-switching port-mode trunk
set interfaces interface-range telenet-clic unit 0 family ethernet-switching vlan members 941-944

On QFX5110: 

sset interfaces xe-0/0/47 description "Telenet WAN DC-1"
set interfaces xe-0/0/47 flexible-vlan-tagging
set interfaces xe-0/0/47 mtu 8000
set interfaces xe-0/0/47 encapsulation flexible-ethernet-services
set interfaces xe-0/0/47 unit 0 family ethernet-switching interface-mode trunk
set interfaces xe-0/0/47 unit 0 family ethernet-switching vlan members WAN-OVERLAY1
set interfaces xe-0/0/47 unit 943 vlan-id 943
set interfaces xe-0/0/47 unit 943 family inet mtu 7500
set interfaces xe-0/0/47 unit 943 family inet address 10.19.43.2/30
set protocols ospf area 0.0.0.0 interface xe-0/0/47.943 bfd-liveness-detection minimum-interval 1000
set protocols ospf area 0.0.0.0 interface xe-0/0/47.943 bfd-liveness-detection minimum-receive-interval 1000
set protocols ospf area 0.0.0.0 interface xe-0/0/47.943 bfd-liveness-detection multiplier 3


{master:0}
root@jtac-qfx5110-48s-4c-r2101> show ospf neighbor 
Address          Interface              State           ID               Pri  Dead
10.19.43.1       xe-0/0/47.943          Full            10.25.255.85     128    31


root@jtac-ex4300-48mp-r2001> show ospf neighbor 

Warning: License key missing; requires 'ospf' license

Address          Interface              State           ID               Pri  Dead
10.19.43.2       ge-0/0/23.943          Full            10.25.255.122    128    38



ISSUE : 

When we do a monitor capture on EX4300, we see that EX4300 is receiving the OSPF hello sent by self. 
QFX5k is reflecting OSPF hello received by EX4300 back to it. 

root@jtac-ex4300-48mp-r2001> monitor traffic interface ge-0/0/23 no-resolve                      
verbose output suppressed, use <detail> or <extensive> for full protocol decode
Address resolution is OFF.
Listening on ge-0/0/23, capture size 96 bytes

13:39:34.614157 Out IP truncated-ip - 30 bytes missing! 10.19.43.1 > 224.0.0.5: OSPFv2, Hello, length 60 >> sent out by EX4300 to QFX5k
13:39:34.614549  In IP truncated-ip - 30 bytes missing! 10.19.43.1 > 224.0.0.5: OSPFv2, Hello, length 60 >> QFX5k reflects the packet back to EX4300

13:39:35.826697  In IP truncated-ip - 30 bytes missing! 10.19.43.2 > 224.0.0.5: OSPFv2, Hello, length 60
13:39:43.637669 Out IP truncated-ip - 30 bytes missing! 10.19.43.1 > 224.0.0.5: OSPFv2, Hello, length 60
13:39:43.638047  In IP truncated-ip - 30 bytes missing! 10.19.43.1 > 224.0.0.5: OSPFv2, Hello, length 60
13:39:44.631874  In IP truncated-ip - 30 bytes missing! 10.19.43.2 > 224.0.0.5: OSPFv2, Hello, length 60


When we do a monitor capture on QFX, we do not see it. 

08:10:40.491523  In IP 10.19.43.1 > 224.0.0.5: OSPFv2, Hello, length 60
08:10:43.287028 Out IP truncated-ip - 30 bytes missing! 10.19.43.2 > 224.0.0.5: OSPFv2, Hello, length 60
08:10:48.528829  In IP 10.19.43.1 > 224.0.0.5: OSPFv2, Hello, length 60
08:10:51.056943 Out IP truncated-ip - 30 bytes missing! 10.19.43.2 > 224.0.0.5: OSPFv2, Hello, length 60

 

Symptoms

QFX5k is reflecting OSPF hello received it .

 

Solution

-The interface has 2 units , Unit 0 and unit 943 , both belong to different families, ethernet switching and inet respectively. 
- If unit 0 is removed , the issue is not seen. 
-If unit 0 is configured as family inet, issue is not seen.
-Issue is only see when both the units are in different families.

 

 

As per the update from the engineering team on the internal PR, This is a BCM limitation when we have Layer 2 VXLANs and Layer 3 IPv4 Logical Interfaces on the same IFD where L2 VxLAN IFL is EP style.

 

Workaround:

When we have Layer 2 VXLANs and Layer 3 IPv4 Logical Interfaces on the same IFD, L2 VxLAN IFL must be configured using service provider style instead of enterprise style

Modification History

2024-05-28 : Article Created

Related Information

Internal PR :  https://gnats.juniper.net/web/default/1798266#description_tab