Policy-Based Routing IP-SLA (Part-2 CCNP)

Ø  SLA Stands for Service Level Agreement

Ø  Allow us to understand the health of  the network along with particular route

Ø  Also allow us to automatically forwards the traffic if one ISP is down to other ISP if we have redundant ISP Connections

Ø  In this scenario we have two ISP Connection coming to our Enterprise Network

1^st Step: - IP-SLA Configuration:-

Ø  Ping 200.200.200.1                            {ISP1}

Ø  Ping 200.200.200.5                {ISP2}     {Check the connectivity}

Ø  R1(config)#ip sla 1                                                         {1:- SLA entry Number}

Ø  R1(config-ip-sla)#icmp-echo 200.200.200.1           {ISP1 ip address}

Ø  R1(config-ip-sla-echo)#timeout 200                      {milliseconds}

Ø  R1(config-ip-sla-echo)#frequency 1                       {Second}

Ø  R1(config-ip-sla-echo)#threshold 300                   {milliseconds}

Ø  R1(config-ip-sla-echo)#exit

ü  200.200.00.1:- What is IP address we wana ping

ü  icmp-echo: - Using Ping

ü  Timeout:-how long we wana wait for Ping response back {or consider ping lost}

ü  Frequency:-how many seconds we sending the ping

ü  Threshold:-how long until we consider that device down

2^nd Step:- Now Start the SLA

Ø  R1(config)#ip sla schedule 1 start-time now life forever

ü  1:-SLA entry number

3^rd Step: - To Make Routing Decision Respond to the SLA {entry or probe}

Ø  R1(config)#track 1 rtr 1

Ø  R1(config-track)#exit

ü  1:-Track Object number

ü  rtr:- Response Time Reporter (RTR) Previous name of IP-SLA

ü  1:- entry number

Track object take the SLA entry and essentially says the ip address/interface is up or down

4^th Step:- Now attach the Track object to our Static routes

Ø  R1(config)#ip route 0.0.0.0 0.0.0.0 200.200.200.1 track 1     

ü  Primary Routes from ISP1

ü  Track 1:- Track object number

Ø  R1(config)#ip route 0.0.0.0 0.0.0.0 200.200.200.5 10       

ü  10 :- Administrative distance      

ü  Backup Route from ISP2

Troubleshooting & Verification Commands:-

Ø  R1#show ip sla statistics

Ø  R1#show track

Ø  R1#show ip route

Now Test

Ø  Shutdown the ISP1 serial interface

Ø  Automatically all the traffic goes to ISP2

After no shut

Ø  And all traffic goes to ISP

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