[j-nsp] VRRP tuning and scaling

[Angel Bardarov]

Hi,
When you configure "fast interval" you have limitation on number of VRRP 
groups - it depends  also on how "fast" is your interval:

vrrp-group 250 {
    virtual-address 1.1.1.252;
    priority 105;
    fast-interval 100;
    preempt {
        hold-time 300;
    }
    accept-data;
}
[edit interfaces ge-0/2/1 unit 2011 family inet address 1.1.1.3/24]
lab at edge-a1-RE0# commit check
[edit interfaces ge-0/2/1 unit 2011 family inet address 1.1.1.3/24]
  'vrrp-group 20'
    Configuration exceeds maximum rate of 200 fast advertisements per second
error: configuration check-out failed

With 100 ms interval the convergence is around 400 ms and you can't have 
more than 20 groups. You can have more than 20 if these additional 
groups don't use "fast interval" feature.

Regards,
Angel


Gard Undheim wrote:
> Hi
>
> Thanks for the answers. I have tested a bit with up to 75 vrrp-groups
> and a interval of 100msec in the lab now, and the boxes is not able to
> to the failover in the expected time (300-400msec). These tests were
> done with two M5's, the actual network will use M120 and M320. I guess
> I'll set the interval to 300 seconds, since this is also what is
> recommended in the 8.5 release notes.
>
> Regards,
> Gard
>
> Jonathan Brashear wrote:
>   
>> Seconded.  Depending on what type of Juniper you're using, VRRP issues
>> can heavily tax a router and cause it to drop bgp with other routers if
>> enough problems pop up.  Dropping the fast-interval time will only
>> hasten these problems.  It's your call, but imo it's a
>> high-risk/low-reward situation tuning the failover to the lowest time
>> possible. 
>>
>>
>> Network Engineer
>>     
>>> 214-981-1954 (office) 
>>> 214-642-4075 (cell)
>>> jbrashear at hq.speakeasy.net 
>>>       
>> http://www.speakeasy.net
>> -----Original Message-----
>> From: juniper-nsp-bounces at puck.nether.net
>> [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of alaerte vidali
>> Sent: Sunday, January 13, 2008 4:04 PM
>> To: juniper-nsp at puck.nether.net
>> Subject: Re: [j-nsp] VRRP tuning and scaling
>>
>> Hi,
>>
>> I believe you will face scalability issues, even though I can only
>> affirm
>> this 100% in Cisco.
>>
>> I suggest you consider not only normal periods of the network. In this
>> case
>> probably it is ok.
>> But add to this all process you have, plus things like instabilities in
>> network (STP issues, link flapping...).
>> Then everything together can result in routers losing track of VRRP
>> neighbor
>> packets due to the large number.
>>
>> Br,
>> Alaerte
>>
>>     
>>> Today's Topics:
>>>
>>>   1. VRRP tuning and scaling (Gard Undheim)
>>>
>>>
>>> ----------------------------------------------------------------------
>>>
>>> Message: 1
>>> Date: Sat, 12 Jan 2008 18:15:58 +0100
>>> From: Gard Undheim <gard at ipnett.no>
>>> Subject: [j-nsp] VRRP tuning and scaling
>>> To: juniper-nsp at puck.nether.net
>>> Message-ID: <4788F5CE.5090905 at ipnett.no>
>>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>>
>>>
>>> Hi
>>>
>>> I am currently tuning VRRP to speed up the failover time. I have set
>>>       
>> the
>>     
>>> fast-interval to 100msec, which is a minimum. Does anyone know how
>>>       
>> these
>>     
>>> settings scale with different numbers of vrrp groups? The customer
>>> currently has 20 vrrp groups, but would it also work fine with as much
>>> as 255 groups and fast interval of 100msec?
>>>
>>>
>>> Thanks for any help!
>>>
>>> Best Regards,
>>> Gard
>>>
>>>
>>>
>>>       
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