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Replies
Taimur Khan
Beginner

Setting Gateway for Loopbacks

Hi,

i have a router which is connected to two isp. ISP1 and ISP2. we are running bgp with both of them. for inbound traffic we are receiving the traffic almost as expected but for outbound traffic all the traffic is following ISP1 always. and we do not wanted like that and need to send traffic to ISP1 and some to ISP2 (both ISP are sending default route through BGP). after doing many changes we did not get desired results so i went with other solution.

 

 

! Step 1

! Define SLA to track the default route and set default route according to availability.

 

! SLA for ISP1 as default Gateway

 

ip sla 15

icmp-echo 172.16.180.161

 

! ISP1 Side IP

 

 

frequency 5

ip sla schedule 15 life forever start-time now

 

!!!!!! Track for SLA 15 to check the status of next hop ISP1

 

 

track 15 ip sla 15 reachability

 delay down 120 up 1

 

! Default route for all traffic is ISP1 with default metrics. and Track the availability of ISP1.

 

ip route 0.0.0.0 0.0.0.0 172.16.180.161 track 15

 

 

! Default route for all traffic to ISP2 with metric 15 set lower then 20 (EBGP)

! ISP2  side   172.17.4.137

 

ip route 0.0.0.0 0.0.0.0 172.17.4.137 15

 

 

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

! For Load balancing create route-map and call the ACL for preferred path.

! ACL to match the subnet we need to prefer to ISP1.

access-list 80 permit 192.12.176.0 0.0.0.255

access-list 81 permit 192.12.177.0 0.0.0.255

 

! ACL to match the subnet we need to prefer to ISP2.

 

access-list 82 permit 192.12.178.0 0.0.0.255

access-list 83 permit 192.12.179.0 0.0.0.255

 

!!!!! IP SLA for main ISP1 and backup ISP2

 

ip sla 16

icmp-echo 172.16.180.161

frequency 5

ip sla schedule 16 life forever start-time now

 

!!!!!! Track for IP SLA 16 for making the next hop for preferred subnet to ISP1

track 16 ip sla 16 reachability

 delay down 120 up 1

 

 

!!!!! IP SLA for main ISP1 and backup ISP2

 

ip sla 17

icmp-echo 172.17.4.137

frequency 5

ip sla schedule 17 life forever start-time now

 

!!!!!! Track for IP SLA 16 for making the next hop for preferred subnet to ISP1

track 17 ip sla 17 reachability

 delay down 120 up 1

 

 

 

 

!!!! Route map to set ISP1 as main and ISP2  as backup for subnet 80 and 81

 

 

route-map MAIN_ISP1_BACK_ISP2 permit 10

match ip address 80 81

 set ip next-hop verify-availability 172.16.180.161 16 track 16

 

!!!! Route map to set ISP2  as main and ISP1 as backup for subnet 82 and 83

 

 

 

route-map MAIN_ISP2_BACK_ISP1 permit 10

match ip address 82 83

 set ip next-hop verify-availability 172.17.4.137 17 track 17

 

int Loopback 100

 ip address 192.12.176.1 255.255.255.255

ip policy route-map MAIN_ISP1_BACK_ISP2

 

 

int Loopback 101

ip address 192.12.177.1 255.255.255.255

ip policy route-map MAIN_ISP1_BACK_ISP2

 

Int Loopback 200

ip address 192.12.178.1 255.255.255.255

ip policy route-map MAIN_ISP2_BACK_ISP1 

 

 

int Loopback 201

ip address 192.12.179.1 255.255.255.255

ip policy route-map MAIN_ISP2_BACK_ISP1 

 

 

After doing this still the traceroute source as any of these loopback is following ISP1 which we do not want.

so kindly let me know where i am making mistake

 

Thanks

16 REPLIES 16

HI @Richard Burts ,

 

So  i will try tomorrow as per your suggestion, to advertise first two most specific subnets plus complete /22 subnet to isp1 and other two specific subnet plus /22 summary route to isp2. it should solve my inbound traffic issue.

For outbound if i try maximum path will it solve both things or not? Kindly advice

And for PBR i replied above that " ip local policy route-map " command is not working at my router. i have shared the version as well kindly check.

 

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If you make the changes that I suggest about advertising into BGP it should achieve your objective for inbound traffic from Internet to you. It should have 2 subnets come to you over ISP 1 while the other 2 subnets come to you over ISP 2. And if either ISP is not working then all traffic should use the ISP that is still working.

For outbound if you try maximum paths it will not achieve your objective. maximum paths will allow BGP to use both default routes. But nothing there will tell the first 2 subnets to use ISP 1 or tell the other 2 subnets to use ISP 2. To achieve that objective you need PBR.

This is what you posted in an earlier response

"ip local-policy route-map"

(config-if)#ip local-policy route-map ISP_FES
^
% Invalid input detected at '^' marker.

Clearly there is a dash between local and policy. local-policy is not a valid command. local policy should be a valid command.

HTH

Rick