Re: Split Horizon

Yep Narbik, I was indeed referring to synchronization/full-mesh I said
as much below. But in a couple of recent discussions on this very
list people (including CCIEs) were referring to this as a BGP split
horizon behavior. I have been traveling a lot lately and sometimes
reading threads one or two full weeks after they've already played
out, so I didn't bother to chime in. In fact, I was just reading one
such thread this morning from maybe a week ago. I half wondered if
R.B's question didn't stem from one of these other threads where the
term "split horizon" was being applied to BGP and hence my post...

Cheers sir,

Scott

On Apr 23, 2009, at 4:35 , Narbik Kocharians wrote:

> I think you mean synchronization
>
> On Thu, Apr 23, 2009 at 2:43 PM, Scott M Vermillion <
> scott_ccie_list_at_it-ag.com> wrote:
>
>> R.B,
>>
>> I would just clean that up a little and replace "packet" with
>> "destination"
>> or something along that line.
>>
>> People sometimes (recently) use this in iBGP discussions, which I
>> believe
>> to be a slightly improper application of the term. The full
>> mesh/synchronization requirement has as much if not more to do with
>> serving
>> as an anti-blackholing mechanism vs. preventing loops from
>> forming. And
>> even to the extent that it does prevent loops, it does so slightly
>> differently as contrasted to, say, RIP split-horizon, so this is
>> not a term
>> that I personally use in the context of BGP. Others do, though,
>> and so this
>> is probably one context worth making note of.
>>
>> The term has also been borrowed for split-horizon DNS and so
>> forth. But it
>> generally infers a behavior where otherwise flooded information is
>> not
>> reflected back towards its point of origin relative to any given
>> point in a
>> topology.
>>
>> What was the catalyst for your question?
>>
>> Regards,
>>
>> Scott
>>
>>
>>
>>
>> On Apr 23, 2009, at 7:03 , Robin Betterley wrote:
>>
>> Hi GS,
>>>
>>> The basic principle is simple: Information about the routing for a
>>> particular packet is never sent back in the direction from which it
>>> was received.
>>>
>>> Is there any other known principle of split horizon?
>>>
>>> Cheers,
>>> R.B
>>>
>>>
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>>
>>
>>
>
>
> --
> Narbik Kocharians
> CCSI#30832, CCIE# 12410 (R&S, SP, Security)
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Received on Thu Apr 23 2009 - 17:21:07 ART