Subject: draft - ospf-scalability-03.txt

From: Vivek Dubey <[email-masked]>
Date: Wed, 16 Apr 2003 05:03:24 -0000

Hi,
Section 2:
2) Reset the Inactivity Timer for an interface whenever any OSPF
    packet is received over that interface (currently this is done
only
    for the Hello packet).
    So OSPF would declare the interface to be down only if no
    OSPF packet is received over that interface for a period
    equaling or exceeding the RouterDeadInterval.

Here what the paragraph implies seems little unclear.
a) Inactivity timer are neighbor specific, so
    why should the one for interface be restarted ?
b) Why should Ospf interface be made down if no packets
    are received on it ?
c) Probably it should be something like this:
    "Reset the inactivity timer for a Neighbor whenever any
    Ospf packet is received from that neighbor"

Or i missed the point the draft tries to make ????

vivek

---

From: Vivek Dubey <[email-masked]>
Date: Sat, 19 Apr 2003 07:37:15 -0000

Hi,
If network is stable and there is no congestion
and outage problems, restart of inactivity timer (for
every OSPF packet over adjacency) might be overhead.

But if "Congestion Detection" leads to ways to prevent
outages "resettting of inactivity timer" this overhead
might be worth it.

"draft-ash-manral-ospf-congestion-control-00.txt " talks
about possible ways of detecting and avoiding
congestion. Again implementations may vary depending upon
requirenments.

For Vishwas:
Is there any new version of
"draft-ash-manral-ospf-congestion-control-00.txt " ???

thanks,
vivek

On Sat, 19 Apr 2003 Dave Katz wrote :
>            Ignoring the reasons for possibly implimenting
>            the below feature...
>
>            As a past contributor to an ARC (architecture
>review
>            committee), a frequent question was, is that
>proposal
>            downward scalable?
>
>            I question whether implimentating, the ability for
>            every OSPF packet over an adj to reset the
>Inactivity
>            timer could cause more harm than good.
>
>            Given a 50k LSDB, with a normal amount of flooding
>            is isn't unlikely that we would see about 100k
>worth
>            of update pkts per hr.
>
>            Would 100k per hr of inactivity timer resets cause
>            harm in routers?
>
>This is an implementation issue.  Those who are sufficiently
>clever will succeed, those who are not will fail.
>
>Protocols like OSPF are filled with scalability issues, and the
>ability to deal with them efficiently is one of the few product
>differentiators.  (Full BGP routing in OSPF anyone?)

---

From: "Choudhury, Gagan L, ALABS" <[email-masked]>
Date: Sun, 20 Apr 2003 18:55:30 -0500

Hi Mitchell,
  Your comment is regarding Recommendation 2 in the draft and the
benefit of this recommendation is that during a period of
congestion it does not declare a adjacency to be down due
to excessively delayed Hello packets as long as other OSPF packets
are received over it. However, Recommendation 1 of the draft 
(prioritizing Hello) also does the same job.  Based on comments on 
the list, in the next version we will point
out that Recommendation 2 is not to be implemented if
Recommendation 1 is already being implemented.  Hopefully
this will satisfy your concern.

Now in case Recommendation 1 is not implemented then we do
propose Recommendation 2.  We feel that in that case the
benefit of not declaring an adjacency down due to delayed
Hellos during periods of congestion outweighs the extra
overhead of more frequent resetting of Inactivity timer.
Please also see the comment from Vivek Dube which seem to
support this position. 

Thanks to yourself, Vivek and others for the comments
which are improving the quality of the draft. With regards,

        Gagan Choudhury   

-----Original Message-----
From: Erblichs [mailto:[email-masked]]
Sent: Friday, April 18, 2003 6:36 PM
To: [email-masked]
Subject: Re: draft - ospf-scalability-03.txt

Group,

        As a past contributor to an ARC (architecture review
        committee), a frequent question was, is that proposal
        downward scalable?

        I question whether implimentating, the ability for
        every OSPF packet over an adj to reset the Inactivity
        timer could cause more harm than good.

        Given a 50k LSDB, with a normal amount of flooding
        is isn't unlikely that we would see about 100k worth
        of update pkts per hr.

        Does anybody else have a concern, that this type of
        item should be explicitly stated within the doc?

        With each 10 sec hello interval, I would expect to
        see 360 resets per nbr of the Inactivity timers.

        Mitchell Erblich
        Sr Software Engineer
        -------------------------------

"Manral, Vishwas" wrote:
>
> Hi Vivek,
>
> This has been updated in version 4 of the draft, which has recently been
> completed. The current text reads: -
>
> "      reset the Inactivity Timer for an adjacency whenever any OSPF
>        packet is received over that adjacency "
>
> Thanks,
> Vishwas
>
> -----Original Message-----
> From: Vivek Dubey [mailto:[email-masked]]
> Sent: Wednesday, April 16, 2003 10:33 AM
> To: [email-masked]
> Subject: draft - ospf-scalability-03.txt
>
> Hi,
> Section 2: