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Re: IP SLA and HSRP - Please help

 
 
Darren Green
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Posts: n/a
 
      04-29-2008
On 29 Apr, 16:23, "Elia Spadoni" <(E-Mail Removed)> wrote:
> Hello
> 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?


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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Darren
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Posts: n/a
 
      04-30-2008
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.
>
> d) To set "how much decrease the priority" I could use this command,
> standby 1 track 1 decrement 20, right?
>

Yes I believe so. I normally just have my HSRP priority set to 105. The
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.
>
> Thank you in advance
>
>

Regards

Darren>
 
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