IP SLA and HSRP - Please help
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Posted by Elia Spadoni on April 29, 2008, 11:23 am
Please log in for more thread options I would like to achieve redundancy but I was not able to understend completely the topic: I read this: http://tcpmag.com/qanda/article.asp?EditorialsID=348 and http://www.nil.si/ipcorner/RedundantMultiHoming/ My scenario is: Router A: SHDSL - int atm0/0.1 public wan ip fast0 - 172.16.0.11 (lan side) Router B: ADSL - int atm0/0.1 public wan ip fast0 - 172.16.0.12 (lan side) The routers are identical, are two Cisco 2650 with 32F/128D and IOS 12.4(17a) ADVSEC I have managed creating the virtual ip of HSRP my troubles are in the IP SLA command. I need that router A pings this IP (example) 77.77.77.50 I need that router B pings this IP (example) 99.99.99.50 The pinged IP is to test the reachability of the upstream router of each connection. I would like to ping it every 30 seconds (frequency 30) and after 3 (three) pings un-answered, the router will change connection from sHDSL to ADSL. After 3 pings answered, the connection is re-routed on the main SHDSL link. Can someone help me? | |||||||||||||||||||
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Posted by Darren Green on April 29, 2008, 5:10 pm
Please log in for more thread options You can configure tracking in many different ways. Personally assuming your SDSL is primary and ADSL is backup, configure HSRP on the LAN side and then on your primary router track the object as part of HSRP.... somthing like: RTR-A ip sla monitor 1 type echo protocol ipIcmpEcho 77.77.77.50 frequency X ip sla monitor schedule 1 life forever start-time now ! track 1 rtr 1 reachability ! int Ethernet 0/0 ip address 1.2.3.4 255.255.255.0 standby 10 ip X.X.X.X standby 10 track 1 standby 10 track ATM0/0 standby 10 priority 105 standby 10 preempt etc..... This way if your tracked object of 1, a ping to 77.77.77.50 fails, the HSRP of this router will be reduced and your secondary ADSL router take over. Look on Cisco for IP SLA Regards Darren | |||||||||||||||||||
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Posted by Elia Spadoni on April 29, 2008, 8:11 pm
Please log in for more thread options Hello, thank you for your answer,
>> I have managed creating the virtual ip of HSRP
>> >> my troubles are in the IP SLA command. >> >> I need that router A pings this IP (example) 77.77.77.50 >> I need that router B pings this IP (example) 99.99.99.50 >> >> The pinged IP is to test the reachability of the upstream router of each >> connection. >> >> I would like to ping it every 30 seconds (frequency 30) >> and after 3 (three) pings un-answered, the router will change connection >> from sHDSL to ADSL. After 3 pings answered, the connection is re-routed >> on >> the main SHDSL link. > You can configure tracking in many different ways. Personally assuming
> your SDSL is primary and ADSL is backup, configure HSRP on the LAN > side and then on your primary router track the object as part of > HSRP.... somthing like: > > RTR-A > > ip sla monitor 1 > type echo protocol ipIcmpEcho 77.77.77.50 > frequency X > ip sla monitor schedule 1 life forever start-time now > ! > track 1 rtr 1 reachability > ! > int Ethernet 0/0 > ip address 1.2.3.4 255.255.255.0 > standby 10 ip X.X.X.X > standby 10 track 1 > standby 10 track ATM0/0 > standby 10 priority 105 > standby 10 preempt > etc..... > > This way if your tracked object of 1, a ping to 77.77.77.50 fails, the > HSRP of this router will be reduced and your secondary ADSL router > take over. > > Look on Cisco for IP SLA > > Regards > > Darren Hello I have read about IP SLA but I did not find any examples suitable for my personal situation. Some questions: a) So, since the SHDSL is the main link, and just if the SHDSL link is down, the ADSL will take over, I need to set the IP SLA commands on the SHDSL router only, right? > standby 10 track 1
> standby 10 track ATM0/0 b) In this way, in the HSRP I will monitor both the status of the ATM0/0 interface AND the "ip sla entry number 1" right? c) But how can I set, ping every 30 seconds and if three pings fail, re-route the connection? I can set the frequency of 30 seconds, but not how many pings need to be failed to lower the priority of the HSRP router. d) To set "how much decrease the priority" I could use this command, standby 1 track 1 decrement 20, right? e) > track 1 rtr 1 reachability
delay down 10 up 20
this will delay the time to 10 seconds to put the HSRP router "offline", right? Thank you in advance | |||||||||||||||||||
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Posted by Darren on April 30, 2008, 3:33 am
Please log in for more thread options Elia Spadoni wrote:
>
> Hello > I have read about IP SLA but I did not find any examples suitable for my > personal situation. > > Some questions: > > a) So, since the SHDSL is the main link, and just if the SHDSL link is > down, the ADSL will take over, I need to set the IP SLA commands on the > SHDSL router only, right? Yes >
>> standby 10 track 1
>> standby 10 track ATM0/0 >
> b) In this way, in the HSRP I will monitor both the status of the ATM0/0 > interface AND the "ip sla entry number 1" right? Yes, I was only giving you an example. You could track the interface as well as the IP SLA entry 1, this is what I normally prefer to do >
> c) But how can I set, ping every 30 seconds and if three pings fail, > re-route the connection? > I can set the frequency of 30 seconds, but not how many pings need to be > failed to lower the priority of the HSRP router. I would need to check the IP SLA documentation at cisco.com. However, remember that HSRP will ordinarily take over is 3 x HSRP hellos are missed and the default is normally 10 x secondary. YOu could modify this timer to 30 seconds also. May be easier. >
Yes I believe so. I normally just have my HSRP priority set to 105. The
> d) To set "how much decrease the priority" I could use this command, > standby 1 track 1 decrement 20, right? > standard decrement in HSRP is 10 and the default priority 100. If my ATM0/0/0 fails or my IP SLA fails, HSRP goes down to 95 and my secondary takes over. > e) > track 1 rtr 1 reachability
> delay down 10 up 20 > > this will delay the time to 10 seconds to put the HSRP router "offline", > right? Again I would need to refer to the IP SLA documentation on line at cisco.com. I will try an take a look a little later today. >
Regards
> Thank you in advance > > Darren>
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> I would like to achieve redundancy but I was not able to understend
> completely the topic:
>
> I read this:
>
> http://tcpmag.com/qanda/article.asp?EditorialsID=348
>
> and
>
> http://www.nil.si/ipcorner/RedundantMultiHoming/
>
> My scenario is:
>
> Router A:
> SHDSL -
> int atm0/0.1 public wan ip
> fast0 - 172.16.0.11 (lan side)
>
> Router B: ADSL -
> int atm0/0.1 public wan ip
> fast0 - 172.16.0.12 (lan side)
>
> The routers are identical, are two Cisco 2650 with 32F/128D and IOS
> 12.4(17a) ADVSEC
>
> I have managed creating the virtual ip of HSRP
>
> my troubles are in the IP SLA command.
>
> I need that router A pings this IP (example) 77.77.77.50
> I need that router B pings this IP (example) 99.99.99.50
>
> The pinged IP is to test the reachability of the upstream router of each
> connection.
>
> I would like to ping it every 30 seconds (frequency 30)
> and after 3 (three) pings un-answered, the router will change connection
> from sHDSL to ADSL. After 3 pings answered, the connection is re-routed on
> the main SHDSL link.
>
> Can someone help me?