BFD for VRRP flapping issue on S5720-HI Switch

Created Aug 17, 2018 15:10:37Latest reply Aug 23, 2018 09:08:55 290 1 0 0
 Issue Description

As the solution design BFD for VRRP being applied to achieve the recovery time within the required 50ms. Currently 17 BFD sessions are configured for VRRP and they are working fine. As soon as customer configure another BFD sessions for newly added Vlanif, all the BFD sessions start flapping randomly.

transparent.gif Alarm Information

Apr  4 2018 17:27:48+03:00 ICC-LAN-UP-1 %BFD/4/STACHG_TODWN(l)[47]:BFD session changed to Down. (SlotNumber=0, Discriminator=8209, Diagnostic=DetectDown, Applications=VRRP | AUTO, ProcessPST=False, BindInterfaceName=Vlanif14, InterfacePhysicalState=Up, InterfaceProtocolState=Up)

transparent.gif Handling Process

1. Checking the BFD for VRRP configuration, and it is right. 

#

bfd vrrp18 bind peer-ip 10.1.1.2 interface Vlanif18 source-ip 10.1.1.1 auto

 min-tx-interval 50

 min-rx-interval 50

 commit

#

#

interface Vlanif18

 ip address 10.1.1.1 255.255.255.0

 vrrp vrid 18 virtual-ip 10.1.1.3

 vrrp vrid 18 priority 110

 vrrp vrid 18 preempt-mode timer delay 250

 vrrp vrid 18 track bfd-session session-name vrrp18

#

2. Checking the device type and the device type is S5720-32C-HI-24S-AC.
3. As customer needs the interval should be within 50ms, so command "set service-mode enhanced" should be confiugred. After add this command, the issue resolved. 
transparent.gif Root Cause

As customer needs the interval should be within 50ms, so command "set service-mode enhanced" should be confiugred. By default, S5720HIs work in normal mode, requiring the interval for receiving BFD packets to be longer than or equal to 100 ms. If the interval cannot meet requirements, run the set service-mode command to change the working mode of an S5720HI to enhanced so that the S5720HI supports a minimum of 3 ms interval.

transparent.gif Solution

Using command "set service-mode enhanced" to set the working mode of the device to enhanced.

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Mark.hu  Adept   Created Aug 23, 2018 09:08:55 Helpful(0) Helpful(0)

Thank you for sharing, very helpful to me.
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