From: Serran (groupstudy@swiftdsl.com.au)
Date: Wed Mar 24 2004 - 11:39:52 GMT-3
Yep. although the standard is 60min. cisco will refresh at 30min so there is
no chance for the lsa to timeout in that way. and there is some
randomness.. as i have seen the age timer hit anywhere from 2000 to 2015.
just curious that's all as i couldn't find any literature about lsa
premature aging having a random function.
thanks wes.
Serran.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Wes Smith
Sent: Thursday, 25 March 2004 1:31 AM
Cc: Ccielab@Groupstudy. Com
Subject: Re: Cisco's documented implementation of OSPF's LS aging -
incorrect?
There is some randomness involved. The doc you reference says they will
last 60 minutes,
LSA Group Pacing will vary the refresh to avoid flooding the network wiht
syncronised updates.
Wes
Serran wrote:
>I was doing some labs on ospf the past couple of days.. when it occured to
>me...
>
>R6#sh ip ospf database
>
> OSPF Router with ID (200.0.0.6) (Process ID 10)
>
> Router Link States (Area 0)
>
>Link ID ADV Router Age Seq# Checksum Link count
>200.0.0.2 200.0.0.2 426 0x80000039 0x0007BA 1
>200.0.0.5 200.0.0.5 511 0x80000007 0x00C883 3
>200.0.0.6 200.0.0.6 1870 0x80000009 0x002706 2
>200.0.0.7 200.0.0.7 1644 0x80000006 0x00A004 2
>200.0.0.8 200.0.0.8 7 (DNA) 0x80000003 0x005B0F 1
>
>
>the lsa type 1 originating from 200.0.0.6 is 1870 seconds... hang on.. that
>is > 30 min. Cisco states in its doco that an lsa will be refreshed
>prematurely (every 30 min), ie. half the max age timer (60 min).
>
>It seems that the timer is not 1800sec but approx 2000sec.
>
>Maybe there is some random factor or correlation with the group pacing
timer
>so it varies + or - a few minutes?
>
>
>12.2:
>http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configurati
o
>n_guide_chapter09186a00800b3f2e.html#1017198
>RFC2328 section 14 goes through some of the details on lsa aging.
>
>
>
>Can anyone add further into this?
>
>
>
>
>Cheers
>Mark.
>
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