HSRP Learn & Backup States

[Mitrixsen]

Hello, everyone.

I have two questions.

I don't quite understand what does the Learn state do. What does it mean that the router hasn't determined the VIP? Don't we as the administrator specify the VIP by configuring HSRP? Which should trigger the INIT state. Also, when does this state occur? I didn't manage to see it in my debug output, the router just moves straight to Listen.

SW1#
HSRP: Vl1 Interface UP 
HSRP: Vl1 Starting minimum intf delay (1 secs) - uptime 997
HSRP: Vl1 Intf min delay expired - uptime 998
HSRP: Vl1 Grp 1 Init: a/HSRP enabled
HSRP: Vl1 Grp 1 Init -> Listen
HSRP: Vl1 Grp 1 Redundancy "hsrp-Vl1-1" state Init -> Backup
HSRP: Vl1 IP Redundancy "hsrp-Vl1-1" update, Init -> Backup
HSRP: Vl1 Grp 1 Listen: d/Standby timer expired (unknown)
HSRP: Vl1 Grp 1 Listen -> Speak
HSRP: Vl1 Grp 1 Redundancy "hsrp-Vl1-1" state Backup -> Speak
HSRP: Vl1 IP Redundancy "hsrp-Vl1-1" update, Backup -> Speak
HSRP: Vl1 Grp 1 Speak: d/Standby timer expired (unknown)
HSRP: Vl1 Grp 1 Standby router is local
HSRP: Vl1 Grp 1 Speak -> Standby
HSRP: Vl1 Grp 1 Redundancy "hsrp-Vl1-1" state Speak -> Standby
HSRP: Vl1 IP Redundancy "hsrp-Vl1-1" standby, unknown -> local
HSRP: Vl1 IP Redundancy "hsrp-Vl1-1" update, Speak -> Standby
HSRP: Vl1 Grp 1 Standby: c/Active timer expired (unknown)
HSRP: Vl1 Grp 1 Active router is local
HSRP: Vl1 Grp 1 Standby router is unknown, was local
HSRP: Vl1 Grp 1 Standby -> Active
HSRP: Vl1 Grp 1 Redundancy "hsrp-Vl1-1" state Standby -> Active
HSRP: Vl1 Grp 1 Added 192.168.1.254 to ARP (0000.0c07.ac01)
HSRP: Vl1 Grp 1 Activating MAC 0000.0c07.ac01
HSRP: Vl1 Grp 1 Adding 0000.0c07.ac01 to MAC address filter - resetting the interface
HSRP: Vl1 IP Redundancy "hsrp-Vl1-1" standby, local -> unknown
HSRP: Vl1 IP Redundancy "hsrp-Vl1-1" update, Standby -> Active
HSRP: Vl1 IP Redundancy "hsrp-Vl1-1" update, Active -> Active

And what exactly is Backup?

That's all, thank you.
David

[Giuseppe Larosa]

Hello @Mitrixsen ,

happy new year

if you are studying for CCIE level lab you need to grab information from RFCs  ( if any) and from cisco config guide and command reference guide.

I you have 4 routers R1,R2,R3,R4 connected to a common L2 LAN or or VLAN ( or emulated LAN VPLS or EVPN).

the init state is started when the interface comes up, for example R4:gi0/3.

HSRP v1 : it uses link local all routers in subnet 224.0.0.2 to detect UDP port 1985  (to be checked)

HSRP v2 :it uses a dedicated link local multicast

>>

HSRP: Vl1 Grp 1 Redundancy "hsrp-Vl1-1" state Standby -> Active
HSRP: Vl1 Grp 1 Added 192.168.1.254 to ARP (0000.0c07.ac01)
HSRP: Vl1 Grp 1 Activating MAC 0000.0c07.ac01
HSRP: Vl1 Grp 1 Adding 0000.0c07.ac01 to MAC address filter - resetting the interface

one active ,one backup per HSRP group

speak means I see other devices

You have names for HSRP group but you use HSRP version 1

>> Vl1 Grp 1 Adding 0000.0c07.ac01 to MAC address filter - resetting the interface

the MAC address is added to the low level driver  of the NIC i.e. Rx:gi0/y

this can cause issues in real world

see

https://www.networkacademy.io/ccna/network-services/hot-standby-router-protocol-hsrp

HTH

Giuseppe

[Mitrixsen]

Hello @Giuseppe Larosa 

Thank you, I wish you a happy new year as well

I am studying for ENCOR at the moment. I've read the RFCs and Cisco documents but neither of them describe the Learn and Backup states too much as I've posted here.

David

[Giuseppe Larosa]

Hello,

I'm busy too look for Jeff Doyle Vol I routing with tcp/ip

HSRP is a FHRP , each protocol has a Finite State Machine for neighborships the debug command illustrates these states

Hope to help

Giuseppe