topic Re: HSRP Taking time to failover in Switching

HSRP Taking time to failover

ankitohc — Wed, 20 Dec 2023 20:24:58 GMT

Hi Team,

I just want to know its just a normal behavaiour - Does it 10 seconds to become active?

Re: HSRP Taking time to failover

MHM Cisco World — Wed, 20 Dec 2023 20:32:44 GMT

Hmm,
it can but I think it slow.
can I see config of HSRP
MHM

Re: HSRP Taking time to failover

M02@rt37 — Wed, 20 Dec 2023 20:54:33 GMT

Hello @ankitohc

In HSRP , the default timers include a 10-second delay before the router with the highest priority becomes the active router. This delay is known as the "Hello Timer" or "Hold Time."

Hello Timer (Hold Time) -- This is the interval at which routers participating in HSRP send hello messages to each other. The default hello time is 3 seconds. If a router does not receive a hello message from the active router within the hold time, it assumes that the active router is no longer available.

Hold Time --The hold time is how long a router considers the HSRP router that sent the last hello message to be the active router. The default hold time is 10 seconds.

So, during the normal operation of HSRP, when a router becomes the active router, it will send hello messages every 3 seconds. If a standby router does not receive a hello message within 10 seconds, it may transition to the active state, assuming that the previously active router is no longer reachable.

If you observe a 10-second delay before a router becomes active in your lab, it aligns with the default HSRP timers. If needed, these timers can be adjusted using the `standby` command on the routers participating in HSRP.

Re: HSRP Taking time to failover

ankitohc — Wed, 20 Dec 2023 21:01:15 GMT

also, getting duplicate error

SW1-

SW1#show run
SW1#show running-config
Building configuration...

Current configuration : 1017 bytes
!
! Last configuration change at 20:20:56 UTC Wed Dec 20 2023
!
version 15.2
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
service compress-config
!
hostname SW1
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
!
ip dhcp pool 1
network 10.10.1.0 255.255.255.0
dns-server 8.8.8.8
default-router 10.10.1.3
!
!
ip cef
no ipv6 cef
!
!
spanning-tree mode pvst
spanning-tree extend system-id
!
vlan internal allocation policy ascending
!
!
!
!
!
!
!
!
!
!
!
!
!
interface Ethernet0/0
!
interface Ethernet0/1
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface Ethernet0/2
!
interface Ethernet0/3

!
interface Vlan1
ip address 10.10.1.1 255.255.255.0
standby version 2
standby 0 ip 10.10.1.3
standby 10 priority 70
standby 11 priority 80
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
!
!
!
!
!
control-plane
!
!
line con 0
logging synchronous
line aux 0
line vty 0 4
login

*Dec 20 20:54:08.942: %IP-4-DUPADDR: Duplicate address 10.10.1.3 on Vlan1, sourced by 0000.0c9f.f00a

Re: HSRP Taking time to failover

ankitohc — Wed, 20 Dec 2023 21:01:55 GMT

SW2>EN
SW2#SHOW RUN
SW2#SHOW RUNning-config
Building configuration...

Current configuration : 835 bytes
!
! Last configuration change at 20:22:35 UTC Wed Dec 20 2023
!
version 15.2
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
service compress-config
!
hostname SW2
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
!
!
!
!
!
!
!
ip cef
no ipv6 cef
!
!
spanning-tree mode pvst
spanning-tree extend system-id
!
vlan internal allocation policy ascending
!

interface Ethernet0/0
!
interface Ethernet0/1
!
interface Ethernet0/2
!
interface Ethernet0/3
!
interface Vlan1
ip address 10.10.1.2 255.255.255.0
standby version 2
standby 10 ip 10.10.1.3
standby 10 priority 99
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
!
!
!
!
!
control-plane
!
!
line con 0
logging synchronous
line aux 0
line vty 0 4
login
!
!
end

SW2#
SW2#
*Dec 20 20:56:37.626: %IP-4-DUPADDR: Duplicate address 10.10.1.3 on Vlan1, sourced by 0000.0c9f.f000
SW2#
SW2#
SW2#
*Dec 20 20:57:08.626: %IP-4-DUPADDR: Duplicate address 10.10.1.3 on Vlan1, sourced by 0000.0c9f.f000

Re: HSRP Taking time to failover

MHM Cisco World — Wed, 20 Dec 2023 21:03:38 GMT

interface Vlan1
ip address 10.10.1.1 255.255.255.0
standby version 2
standby 0 ip 10.10.1.3
standby 10 priority 70 <- no need
standby 11 priority 80 <- no need

You config priority to group not use' you need

Standby 0 priority (make it different to elect the active hsrp)

Config root primary in active hsrp l3sw

Config root secondary in standby l3sw hsrp

Config hsrp preempt in both l3sw

Wr config

Turn off then turn on

After that check recover time

MHM

Re: HSRP Taking time to failover

MHM Cisco World — Wed, 20 Dec 2023 21:05:27 GMT

In l3sw two the hsrp group is wrong you need to use same hsrp group in both l3sw hsrp

MHM

Re: HSRP Taking time to failover

ankitohc — Wed, 20 Dec 2023 21:43:06 GMT

@MHM Cisco World

I have corrected the confguration now its reduced however its still 5 seconds

Re: HSRP Taking time to failover

MHM Cisco World — Wed, 20 Dec 2023 21:50:17 GMT

Reduce and there is no duplicate?

If Yes we are in right way

Now can you share last config let me make double check.

Thanks

MHM

Re: HSRP Taking time to failover

ankitohc — Wed, 20 Dec 2023 22:01:01 GMT

Duplicate error is gone.. let me share your latest config

SW1#wr
Building configuration...
Compressed configuration from 969 bytes to 658 bytes[OK]
SW1#
*Dec 20 21:58:05.038: %SYS-5-CONFIG_I: Configured from console by console
SW1#
SW1#show run
SW1#show running-config
Building configuration...

Current configuration : 969 bytes
!
! Last configuration change at 21:58:05 UTC Wed Dec 20 2023
!
version 15.2
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
service compress-config
!
hostname SW1
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
!
!
!
!
!
!
ip dhcp pool 1
network 10.10.1.0 255.255.255.0
dns-server 8.8.8.8
default-router 10.10.1.3
!
!
ip cef
no ipv6 cef
!
!
spanning-tree mode pvst
spanning-tree extend system-id
!
vlan internal allocation policy ascending
!
!
!
!
!
!
!
!
!
!
!
!
!
interface Ethernet0/0
!
interface Ethernet0/1
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface Ethernet0/2
!
interface Ethernet0/3
!
interface Vlan1
ip address 10.10.1.1 255.255.255.0
standby version 2
standby 0 ip 10.10.1.3
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
!
!
!
!
!
control-plane
!
!
line con 0
logging synchronous
line aux 0
line vty 0 4
login
!
!
end

Re: HSRP Taking time to failover

ankitohc — Wed, 20 Dec 2023 21:59:38 GMT

SW2#show run
SW2#show running-config
Building configuration...

Current configuration : 810 bytes
!
! Last configuration change at 21:56:10 UTC Wed Dec 20 2023
!
version 15.2
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
service compress-config
!
hostname SW2
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
!
!
!
!
!
!
!
ip cef
no ipv6 cef
!
!
spanning-tree mode pvst
spanning-tree extend system-id
!
vlan internal allocation policy ascending
!
!
!
!
!
!
!
!
!
!
!
!
!
interface Ethernet0/0
!
interface Ethernet0/1
!
interface Ethernet0/2
!
interface Ethernet0/3
!
interface Vlan1
ip address 10.10.1.2 255.255.255.0
standby version 2
standby 0 ip 10.10.1.3
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
!
!
!
!
!
control-plane
!
!
line con 0
logging synchronous
line aux 0
line vty 0 4
login

Re: HSRP Taking time to failover

M02@rt37 — Wed, 20 Dec 2023 22:02:47 GMT

@ankitohc

HSRP adjacency formation involves routers exchanging hello messages to discover each other's presence and determine the active and standby roles. The hello messages are part of the HSRP timers, including the hello interval and hold time.

Lowering the hello interval allows for faster detection of neighbor routers and can speed up the convergence process. However, there is a practical limit. Even with very short hello intervals, the overall convergence time is constrained by the routers' processing capabilities, including CPU power and other internal processes...

Re: HSRP Taking time to failover

MHM Cisco World — Wed, 20 Dec 2023 22:05:56 GMT

You dont config spanning root primary in active

And spanning root secondary in standby

Do this make sure stp root is active l3sw hsrp.

MHM

Re: HSRP Taking time to failover

ankitohc — Wed, 20 Dec 2023 22:32:33 GMT

Final config

hostname SW1
ip dhcp pool 1
network 10.10.1.0 255.255.255.0
dns-server 8.8.8.8
default-router 10.10.1.3

spanning-tree mode pvst
spanning-tree extend system-id
spanning-tree vlan 1 priority 24576
!
vlan internal allocation policy ascending
!
interface Ethernet0/0
!
interface Ethernet0/1
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface Ethernet0/2
!
interface Ethernet0/3
!
interface Vlan1
ip address 10.10.1.1 255.255.255.0
standby version 2
standby 0 ip 10.10.1.3
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
!
!
!
!
!
control-plane
!
!
line con 0
logging synchronous
line aux 0
line vty 0 4
login
!
!

hostname SW2

spanning-tree mode pvst
spanning-tree extend system-id
spanning-tree vlan 1 priority 28672
!
vlan internal allocation policy ascending
!
interface Ethernet0/0
!
interface Ethernet0/1
!
interface Ethernet0/2
!
interface Ethernet0/3
!
interface Vlan1
ip address 10.10.1.2 255.255.255.0
standby version 2
standby 0 ip 10.10.1.3
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server

control-plane
!
!
line con 0
logging synchronous
line aux 0
line vty 0 4
login
!
!
end

SW2#

Re: HSRP Taking time to failover

Joseph W. Doherty — Wed, 20 Dec 2023 23:48:21 GMT

Ditto.

I recall (?) HSRPv2 supports subsecond hellos, so usually possible to get a failure switch over in under 2 seconds. To get subsecond failure switch over I recall you'll usually will want BFD support.

Re: HSRP Taking time to failover

paul driver — Wed, 20 Dec 2023 23:56:46 GMT

Hello
The defaults are hello/hld timers are 3/10 seconds respectively so what you see is valid, if you wish to decrease thses timer then you can do so:
Example
standby 10 timers msec 250 msec 800

sh standby | be Group 10

Re: HSRP Taking time to failover

Joseph W. Doherty — Thu, 21 Dec 2023 00:39:50 GMT

Lots of good HSRP details in https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipapp_fhrp/configuration/xe-3s/fhp-xe-3s-book/fhp-hsrp.html

For example:

You can lower these timer settings to speed up the failover or preemption, but, to avoid increased CPU usage and unnecessary standby state flapping, do not set the hello timer below one second or the hold timer below four seconds.

If the above catches your attention, as it might, when you get into HSRP v1 versus V2, and BFD usage, you'll better understand HSRP, very useful if you want to reduce its default failure switch over time.

Re: HSRP Taking time to failover

MHM Cisco World — Thu, 21 Dec 2023 04:49:59 GMT

now how many packet you lose ?

MHM

Re: HSRP Taking time to failover

ankitohc — Thu, 21 Dec 2023 22:19:21 GMT

I dont see any major changes in failover even I changed the timers

Re: HSRP Taking time to failover

MHM Cisco World — Fri, 22 Dec 2023 07:23:14 GMT

Now we still have two option

1-Use router port instead of vlan svi

2-Use bfd (note bfd in gns3 not work it can crash your router in lab)

MHM