HSRP and IP SLA Configuration with Additional Features of Boolean Object Tracking – Network Redundancy configuration on Cisco Router

Network Redundancy-:

Network redundancy and failover is mission critical for any organization to minimize the downtime and continuity of network services. Network redundancy can be achieved with the help of alternative links, deploy standby network devices (Routers and Switches) and communication channels that needs to be installed within network infrastructure.

Internet link redundancy is a process of backup mechanism for quickly swap network operations on to redundant infrastructure in the occurrence of Planned/unplanned network outages. This Process can be achieved through manually and automatic link failover when the primary network path is unavailable.

Network redundancy ensuring network reachability and keep the services up and running for end users in case of device failure, link failure within network infrastructure.

How to Achieve Network Redundancy

This article describe that how to achieve network level redundancy with HSRP and IP SLA (Service Level Agreements) with additional features of Boolean object tracking list toward internet.

HSRP

HSRP is Cisco standard proprietary protocol that provides network reachability and provides first-hop redundancy for IP hosts.HSRP tend to configure with a set of routers interfaces to work together to present a single virtual interface or default gateway for IP hosts on a LAN .

HSRP need to be configured on Routed network segment (Routers and L3 Switches) and it provides a virtual MAC (Media Access Control) address and an IP address that is single address shared between a group of HSRP configured routers and switches. The virtual address (MAC and IP) become the logical gateway for LAN users.

However, Logical address never goes down and it’s represents the group of HSRP routers which are configured as backup gateway to each others. One of the router selected as active router (Based on HSRP priority and router in the HSRP group with the highest priority value becomes the active router) and other routers as standby members in the HSRP group.

IP SLAs (Service Level agreement)

Cisco IOS software leverage with IP SLA feature which allow the administrator to Analyze active traffic-monitoring on the device interfaces to monitor continuous traffic on the Network. IP SLAs features used to measure the network connectivity toward the upstream network such as ISP.IP SLAs provides network level redundancy if the primary Link goes down then the traffic will be shifted automatically on backup link.

Objective -:

This article will describes the configuration and implementation of HSRP and IP SLA (Service Level Agreements) with additional features of Boolean object tracking in order to achieve network level redundancy and auto failover.

Figure -: Network diagram for HSRP and IP SLA (Service Level Agreements) with additional features of Boolean object tracking

Edge-Router-1-:

track 4 ip sla 1
track 5 ip sla 2
track 6 list boolean or
object 4
object 5

Note -: Created two track objects (track 4 and track 5 with SLAs tracker and both track objects called in track 6 object with Boolean or condition)

Object tracking tracks the combined states of defined objects and it used with the following Boolean functions:

AND – All the objects defined in the track list to be up.
OR – At least one object should be up.

ip sla 1
icmp-echo 8.8.8.8
frequency 30
ip sla schedule 1 life forever start-time now

ip sla 2
icmp-echo 4.2.2.2
frequency 30
ip sla schedule 2 life forever start-time now

Note -: Created two IP SLA and ping initiates to public IP address 8.8.8.8 and 4.2.2.2 to ensure continuous reachability to internet.

interface GigabitEthernet0/0
description inside Interface
ip address 172.16.1.2 255.255.255.0
standby 0 ip 172.16.1.1
standby 0 priority 150
standby 0 preempt
standby 0 track 6 decrement 30

Edge-Router-2-:

track 1 interface GigabitEthernet0/1 line-protocol

interface GigabitEthernet0/0
ip address 172.16.1.3 255.255.255.0
standby 0 ip 172.16.1.1
standby 0 priority 145
standby 0 preempt delay minimum 60
standby 0 track 1 decrement 10

Show command to check the SLA statistics

Edge-Router-1#sh ip sla statistics
IPSLAs Latest Operation Statistics
IPSLA operation id: 1
Latest RTT: 16 milliseconds
Latest operation start time: 13:09:52 EDT Fri May 5 2017
Latest operation return code: OK
Number of successes: 3
Number of failures: 0
Operation time to live: Forever
IPSLA operation id: 2
Latest RTT: 16 milliseconds
Latest operation start time: 13:09:52 EDT Fri May 5 2017
Latest operation return code: OK
Number of successes: 3
Number of failures: 0
Operation time to live: Forever