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loloski
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Joined: Mon Mar 15, 2021 9:10 pm
Location: Philippines

OSPF Adjancency issues (mixed ROS v6 & ROS v7)

Fri Apr 18, 2025 4:54 am

Background

All routers and participating switches jumbo frame is enable and it works great
All Ros v7 routers participating in OSPF with BFD enable established adjacency,exchanging routes and it works as expected

Issue

Neighbor Ros V6.49.18 stuck in Ex-Start (if BFD is enable) cycle between Ex-Start and Exchange (if BFD is disable) and of course wouldn't form adjacencies to ROS v7 routers


CCR1036 ROS V6.49.18
/routing ospf area
add area-id=0.0.0.1 name="AREA 1"
/routing ospf instance
set [ find default=yes ] disabled=no router-id=192.168.65.5
/routing ospf area range
add area="AREA 1" range=10.5.48.0/20
/routing ospf interface
add cost=2 interface=internal network-type=broadcast use-bfd=yes
add cost=1 disabled=no interface=internal_v2 network-type=broadcast
add interface=bridge network-type=point-to-point
/routing ospf network
add area="AREA 1" disabled=no network=10.5.48.0/20
add area=backbone disabled=no network=192.168.33.0/24
add area=backbone network=192.168.30.0/24
[rchan@routerX] > /interface vlan print 
Flags: X - disabled, R - running 
 #   NAME                   MTU ARP             VLAN-ID INTERFACE                
 0 R internal             10218 enabled              30 sfp-sfpplus1             
 1 R ;;; For LibreQoS
     internal_v2          10218 enabled            4002 sfp-sfpplus1             
 2 R v50                  10218 enabled              50 sfp-sfpplus1             
[rchan@routerX] > 

[rchan@routerX] > /routing ospf neighbor print 
 0 instance=default router-id=192.168.65.1 address=192.168.30.1 
   interface=internal priority=128 dr-address=192.168.30.2 
   backup-dr-address=192.168.30.1 state="ExStart" state-changes=3 
   ls-retransmits=0 ls-requests=0 db-summaries=0 

 1 instance=default router-id=192.168.65.4 address=192.168.30.2 
   interface=internal priority=128 dr-address=192.168.30.2 
   backup-dr-address=192.168.30.1 state="ExStart" state-changes=3 
   ls-retransmits=0 ls-requests=0 db-summaries=0 
[rchan@routerX] >


CCR2116 ROS V7.17.2

[rchan@routerY] > /routing/ospf/neighbor/print 
Flags: V - virtual; D - dynamic 
 0  D instance=ospf-instance-1 area=backbone address=192.168.30.2 priority=128 
      router-id=192.168.65.4 dr=192.168.30.2 bdr=192.168.30.1 state="Full" 
      state-changes=6 adjacency=57m22s timeout=38s 

 1  D instance=ospf-instance-1 area=backbone address=192.168.30.3 priority=1 
      router-id=192.168.65.5 dr=192.168.30.2 bdr=192.168.30.1 state="ExStart" 
      state-changes=3 timeout=35s 
[rchan@routerY] > /interface/vlan/print 
Flags: R - RUNNING
Columns: NAME, MTU, ARP, VLAN-ID, INTERFACE
#   NAME          MTU  ARP      VLAN-ID  INTERFACE   
0 R Internal     9566  enabled       30  sfp-sfpplus1
;;; For LibreQoS
1 R Internal_v2  9566  enabled     4000  sfp-sfpplus1
2 R Management   9566  enabled       65  sfp-sfpplus2
3 R Tr69         9566  enabled       48  sfp-sfpplus1
[rchan@routerY] > 
I can't upgrade CCR 1036 to latest v7 please don't ask :) I can't disable jumbo frames in all equipment because they are running in production I will try to experiment on spare equipment
Does anyone has an idea on triage the issues beside reducing the MTU to 1500 across the board? has anyone has similar situation and tips or notes please, thank you!
 
User avatar
loloski
Member
Member
Topic Author
Posts: 481
Joined: Mon Mar 15, 2021 9:10 pm
Location: Philippines

Re: OSPF Adjancency issues (mixed ROS v6 & ROS v7)

Fri Apr 18, 2025 9:54 am

I resolved this by reducing MTU from 10218 to 9566, now both rosv6 and rosv7 is happily working as it should