“HSRP + IP SLA monitoring of distant IP” is a most popular failover strategy whereby a distant IP is tracked to offer routing redundancy for routing IP site visitors not depending on the supply of any single.
Many a instances community implementers/directors will observe Service supplier DNS or another globally accessible International IP (through IP SLA monitor or RTR function set utilizing ICMP protocol ).
A few of tracked IPs I bear in mind could also be 8.8.8.8 or 4.2.2.2. Although I is probably not referring to those IPs, nevertheless let’s not neglect that tracked International IPs could block ICMP ping to mitigate safety threats like DOS/DDOS assaults. On this case, HSRP observe protocol dependence on International IP monitoring could fail.
To deal with this example, we could use Default Route HSRP monitoring.
Lab State of affairs: HSRP with Default Route Monitoring
Under is one lab state of affairs created to assist perceive the setup and requisite configuration of Default Route Monitoring:
Observe –
BGP timers have been manipulated in lab setup for sooner convergence. This can be totally different from actual life state of affairs.
R1
!
interface FastEthernet0/0
ip tackle 192.168.123.1 255.255.255.0
!
ip route 0.0.0.0 0.0.0.0 192.168.123.4
R2
interface FastEthernet0/0
ip tackle 192.168.123.2 255.255.255.0
standby 1 ip 192.168.123.4
standby 1 precedence 110
standby 1 preempt
standby 1 observe 1 decrement 20>>>>>>> Decrement by 20 when tracked route just isn’t accessible
!
interface FastEthernet0/1
ip tackle 192.168.24.2 255.255.255.0
!
router bgp 2
community 192.168.24.0
timers bgp 10 30 20 >>>> Timers up to date for sooner convergence
redistribute static metric 50
neighbor 192.168.24.4 remote-as 4
neighbor 192.168.24.4 soft-reconfiguration inbound
!
ip route 1.1.1.0 255.255.255.0 192.168.123.1
R3
standby 1 ip 192.168.123.4
standby 1 preempt
!
interface FastEthernet0/1
ip tackle 192.168.34.3 255.255.255.0
!
router bgp 2
no synchronization
community 192.168.34.0
timers bgp 10 30 20
redistribute static metric 100
neighbor 192.168.34.4 remote-as 4
neighbor 192.168.34.4 soft-reconfiguration inbound
no auto-summary
!
ip route 1.1.1.0 255.255.255.0 192.168.123.1
R4
!
interface FastEthernet0/0
ip tackle 192.168.24.4 255.255.255.0
!
interface FastEthernet0/1
ip tackle 192.168.34.4 255.255.255.0
!
router bgp 4
no synchronization
bgp log-neighbor-changes
community 0.0.0.0
community 4.4.4.0 masks 255.255.255.0
community 192.168.24.0
community 192.168.34.0
timers bgp 10 30 20
neighbor 192.168.24.2 remote-as 2
neighbor 192.168.24.2 soft-reconfiguration inbound
neighbor 192.168.34.3 remote-as 2
no auto-summary
!
ip route 0.0.0.0 0.0.0.0 Null0
Subsequent , time to confirm the configuration as beneath –
R2
Interface Grp Prio P State Lively Standby Digital IP
Fa0/0 1 110 P Lively native 192.168.123.3 192.168.123.4 >>>>>> Native Router is HSRP Grasp
R2#sh ip route 0.0.0.0
Routing entry for 0.0.0.0/0, supernet >>>>>>> Default Route entry in Routing desk
Recognized through “bgp 2”, distance 20, metric 0, candidate default path
Tag 4, sort exterior
Final replace from 192.168.24.4 00:01:55 in the past
Routing Descriptor Blocks:f
* 192.168.24.4, from 192.168.24.4, 00:01:55 in the past
Route metric is 0, site visitors share rely is 1
AS Hops 1
Route tag 4
R2#present observe 1
Monitor 1
IP route 0.0.0.0 0.0.0.0 reachability
Reachability is Up (BGP) >>>>>>>> Default Route is being learnt through BGP
10 adjustments, final change 00:01:56
First-hop interface is FastEthernet0/1
Tracked by:
HSRP FastEthernet0/0 1
R1
Tracing the path to 4.4.4.4
1 192.168.123.2 52 msec 56 msec 60 msec >>>>>> Traceroute takes path through R2 (HSRP Lively) path to succeed in R4 loopback
2 192.168.24.4 124 msec 120 msec 88 msec
Subsequent, we’ll shut interface “Fa0/0” of R4 as per beneath diagram:
R4 –
R4(config-if)#shut
Under configuration exhibits that R2 is HSRP standby whereas R3 turns into HSRP lively.
R2 –
|
Interface Grp Prio P State Lively Standby Digital IP
Fa0/0 1 90 P Standby 192.168.123.3 native 192.168.123.4
R2#sh ip route 0.0.0.0
% Community not in desk
R2#sh observe 1
Monitor 1
IP route 0.0.0.0 0.0.0.0 reachability
Reachability is Down (no route)
9 adjustments, final change 00:01:14
First-hop interface is unknown
Tracked by:
HSRP FastEthernet0/0 1
R3 –
Interface Grp Prio P State Lively Standby Digital IP
Fa0/0 1 100 P Lively native 192.168.123.2 192.168.123.4
As soon as R3 turns into the HSRP grasp (Lively) , Traceroute from R1 Loopback to R4 Loopback ought to take path through R3 as beneath –
R1 –
Tracing the path to 4.4.4.4
1 192.168.123.3 64 msec 60 msec 60 msec
2 192.168.34.4 120 msec 116 msec 124 msec
Proceed Studying:
A number of HSRP (MHSRP): Load Sharing FHRP
