IP SLA with Object Tracking
- Configuration example
-Troubleshooting
Where it can be implemented
• Static Routing
• Hot Standby Router Protoco (HSRP)
• Policy Based Routing (PBR)
When NOT to use Object Tracking
• Directly connected
interfaces.
Tracks
G0/0
G0/0
RA
• Running routing
protocol (i.e. RIP,
OSPF, EIGRP, BGP,
etc.)
RB
No route being
advertised
200.2.2.0/24
192.168.1.0/24
RA
RC
RD
Configuration Components
IP SLA
• Define IP SLA Operation
Object Tracking
• Link track to IP SLA Operation
Objects
• Link objects to track. Such as
Static route, PBR, HSRP, etc.
Static Routing with Object Tracking
On RA:
interface Ethernet0/0
description primary-link
ip address 200.1.1.2 255.255.255.0
!
interface Ethernet0/1
description backup-link
ip address 200.2.2.2 255.255.255.0
!
ip sla 1
icmp-echo 212.23.1.1 source-ip 200.1.1.2
frequency 3
ip sla schedule 1 life forever start-time now
track 2 ip sla 1 reachability
!
ip route 0.0.0.0 0.0.0.0 200.1.1.1 track 2
ip route 0.0.0.0 0.0.0.0 200.2.2.1 250
!
access-list 101 permit icmp any host 212.23.1.1
route-map LOCAL-POLICY permit 10
match ip address 101
set ip next-hop 200.1.1.1
!
ip local policy route-map LOCAL-POLICY
HSRP with Object Tracking
On RA (Active Router):
ip sla 1
icmp-echo 4.2.2.2
frequency 3
ip sla schedule 1 life forever start-time now
!
track 2 ip sla 1 reachability
!
interface Ethernet0/0
ip address 10.10.10.1 255.255.255.0
standby 1 ip 10.10.10.3
standby 1 priority 110
standby 1 preempt
standby 1 track 2 decrement 15
!
access-list 101 permit icmp any host 4.2.2.2
route-map LOCAL-POLICY permit 10
match ip address 101
set ip next-hop 200.1.1.1
!
ip local policy route-map LOCAL-POLICY
PBR with Multiple Object Tracking
On RA:
ip sla 1
icmp-echo 200.1.1.2
frequency 3
ip sla schedule 1 life forever start-time now
!
ip sla 2
icmp-echo 200.2.2.2
frequency 3
ip sla schedule 2 life forever start-time now
!
track 11 ip sla 1 reachability
track 22 ip sla 2 reachability
!
access-list 101 permit 10.10.10.0 0.0.0.255 any
route-map LAB permit 10
match ip addess 101
set ip next-hop verify-availability 200.1.1.2 10 track 11
set ip next-hop verify-availability 200.2.2.2 20 track 22
!
Interface Ethernet1/0
ip address 10.10.10.1 255.255.255.0
ip policy route-map LAB
Parameters
• Frequency
Sets the rate at which a specified Cisco IOS IP SLAs operation is sent
into the network.
• Timeout
Sets the amount of time for which the Cisco IOS IP SLAs operation
waits for a response from its request packet.
• Threshold
Sets the rising threshold that generates a reaction event and stores
history information for the Cisco IOS IP SLAs operation.
Example:
ip sla 1
icmp-echo 212.23.1.1
timeout 500
threshold 2
frequency 3
ip sla schedule 1 life forever start-time now
“Show” Commands for IP SLA
• show ip sla statistics
Displays the current state of the Cisco IOS IP SLAs operation
–Example:
–R1#show ip sla statistics
–Round Trip Time (RTT) for
Index 1
–
Latest RTT: 1 milliseconds
–Latest operation start time: *03:55:56.835 EST Mon Oct 25 2010
–Latest operation return code: OK
–Number of successes: 87
–Number of failures: 24
–Operation time to live: Forever
IP SLA operations status:
OK = good
Over Threshold = exceed threshold < timeout
Timeout = over timeout value
Duration of operation
Successes & Failure
icmp packet statistics
“Show” Commands for IP SLA
• show ip sla configuration
The output will list the supported operations
–
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Example:
Operation number
R1#sh ip sla configuration
Entry number: 1
Type of operation to perform: icmp-echo
Target address/Source address: 212.23.1.1/200.1.1.2
Operation timeout (milliseconds): 500
Schedule:
Operation frequency (seconds): 3
Next Scheduled Start Time: Start Time already passed
…..
Life (seconds): Forever
Threshold (milliseconds): 2
….
Operation
duration
Threshold
(msec)
Operation type
Source & destination
addresses
Timeout
(msec)
Frequency
(sec)
“Show” Commands for Object
Tracking
• show track
Display the detail of the tracked objects
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Example:
R1#sh track
Track number
Track 1
Response Time Reporter 1 reachability
Reachability is Up
3 changes, last change 01:31:14
Latest operation return code: OK
Latest RTT (millisecs) 1
Tracked by:
STATIC-IP-ROUTING 0
Type of objects
tracked by this
track number
IP SLA operation number. The
object is tracking the
reachability of ip sla 1.
Reachability or State
status
- Up or down
IP SLA operations status:
OK = good
Over Threshold = exceed threshold < timeout
Timeout = over timeout value
“Show” Commands for Object
Tracking
• show track brief
Display a list of the tracked objects and its status
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Example:
R1#sh track brief
Track Object
1
rtr 1
2
rtr 1
Parameter
reachability
state
Value Last Change
Up
01:47:32
Down 00:33:33
Track Number
IP SLA operation
that the track is
tracking
Reachability or
State
Reachability or
State status
up/down
“Show” Commands for Static
Routing
• show ip route track-table
To display information about the tracked static table.
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–
–
Example:
R1#sh ip route track-table
ip route 0.0.0.0 0.0.0.0 200.1.1.1 track 1 state is [up]
Track Number
State of tracked
static route
- up/down
“Show” Commands for PBR
• Show ip access-list [access number]
Using the access-list to confirm if the icmp packets are routed
through the right path.
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Example:
R1#sh ip access-lists
Extended IP access list 101
10 permit icmp any host 212.23.1.1 (23 matches)
Extended IP access list 102
10 permit icmp host 212.23.1.1 host 200.1.1.2 (15 matches)
Troubleshooting Steps
Step 1: Ping Test
Step 2: IP SLA
• Check IP SLA operation status
Step 3: Object Tracking
• Check tracked object status
Step 4: Tracked Static Route/PBR/HSRP
• Check routing table
• Check HSRP router roles
• Check route-map (show ip route-map & show ip policy)
Useful Debugs
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•
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IP SLA: debug ip sla trace, debug ip sla error
Object Tracking: debug track
ICMP packet: debug ip icmp, debug ip packet <access-list>
HSRP: debug standby event/packets
PBR: debug ip policy, debug route-map
Reference
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Introduction to IP SLA
http://www.cisco.com/en/US/tech/tk920/tsd_technology_support_sub-protocol_home.html
Reliable Static Routing Backup Using Object Tracking
http://www.cisco.com/en/US/docs/ios/12_3/12_3x/12_3xe/feature/guide/dbackupx.html
Policy Based Routing (PBR)
http://www.cisco.com/en/US/products/ps6637/products_ios_protocol_option_home.html
PBR Support for Multiple Tracking Options
http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gtpbrtrk.html
Enhanced Object Tracking
http://www.cisco.com/en/US/docs/ios/ipapp/configuration/guide/ipapp_eot.html
Configuring HSRP with Object Tracking
http://www.cisco.com/en/US/docs/ios/ipapp/configuration/guide/ipapp_hsrp.html
Configuring GLBP with Object Tracking
http://www.cisco.com/en/US/docs/ios/ipapp/configuration/guide/ipapp_glbp.html
Configuring VRRP with Object Tracking
http://www.cisco.com/en/US/docs/ios/ipapp/configuration/guide/ipapp_vrrp.html