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Date:      Thu, 06 Apr 2000 15:51:00 -0500
From:      Ryugen@palaver.org (Ryugen C. Fisher)
To:        Javier Frias <javier@nyi.net>
Cc:        Joe Greco <jgreco@ns.sol.net>, dev@inetu.net, isp@freebsd.org
Subject:   Re: flat network
Message-ID:  <4.3.1.2.20000406155000.00a87ae0@mail.palaver.org>
In-Reply-To: <38ECED38.421C71A7@nyi.net>
References:  <200004090128.UAA92724@aurora.sol.net>

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At 03:02 PM 4/6/00, Javier Frias wrote:
>Joe Greco wrote:
> >
> > > I've  had quite a bid different experience with vlans.
> > > At least on catalyst switches.
> >
> > Don't talk to me about Catalyst switches.  Not today.  Cisco sucks.
> >
>
>i used to think like that.... we used to use cabletron switches
>and one of their 8000 routers, just a test. OH MY GOD
>those things never worked. we even had two cabletron engineers
>here for 9 days. and even they couldn't get it to work right.
>
>we went back to cisco like crack whores after their pimp.
>
>so yes, cisco i snot perfect, am i hope a good contender comes
>out , but so far, their products have worked as advertise,
>and their support is next to none.
>
>true they are a bit overpriced, but with good reseller channels, you'll
>be amazed.
>i have gotten equipment for less than 1/3 as advertised.
>
>
>
> > > with vlans, arp is reduced. ARP works by broadcasting a packet to all
> > > hosts attached
> > > to an Ethernet segment. Since a vlans virtually reduces the number of
> > > hosts
> > > on each "Ethernet Segment" or "vlan", the number of host an arp request
> > > reaches
> > > is smaller.
> >
> > You're not talking to an idiot.  With routing protocols, ARP is reduced
> > further, to the point where the only ARP traffic on the network is for the
> > physical interfaces present on the network.
> >
>
>i'm sorry if i made it look that way, i know your not ;)
>just for the record, I in no way think you are an idiot.
>
>true, there are other ways, i never said vlans where the only answer.
>but just a simple solution.
>
>
> > If you have one router and one machine on a network, with ARP you still 
> have
> > the potential to have as many ARP entries as you do virtual 
> servers.  If you
> > would like a practical demonstration of why this is bad, go generate about
> > 65,000 virtual servers on such a machine, and then ask for stuff from 
> all of
> > them.  Note the behaviour of the ARP cache on your routers and switches.
> > The behaviour is O(N), and you are screwed when N exceeds the capacity of
> > the ARP table on the device.  God forbid you've more than one server on the
> > net!
> >
> > If you have one router and one machine on a network, with OSPF you have
> > exactly two ARP entries - and no need for the router to ARP for each 
> virtual
> > server.  If you would like a practical demonstration of why this is good,
> > do the same test as above.  The behaviour is O(1).
> >
>
>very true.
>as a side note, i think he meant 200 actual servers, not 200 vservers.
>
>
> > > To move servers between facilities you need a flat network? you can move
> > > vlans accross
> > > switches. Plus, there are quite a large nmber of ways you can do this,
> > > without
> > > the need of a huge flat network.
> >
> > I wasn't proposing the creation of a huge flat network.  My largest
> > production network has a netmask of 0xfffffff0.  I move servers between
> > facilities with no problems, thanks to OSPF.  Do a traceroute to both
> > dns1.sol.net and dns2.sol.net, numbered right next to each other, for a
> > trivial example.
> >
>
>sorry, my misunderstanding.
>
> > > vlans also offer quite a big more security than a flat network.
> > > crosstalk is almost eliminated.
> > >
> > > In the isp market, how some companies provide colocation
> > > without giving a customer a separate vlan is beyond my comprehesion.
> >
> > Use a separate routed network.  Broaden your horizons.
>
>i understand you reasoning.
>
> > --
> > ... Joe
> >
>
>


Did someone say 'Livingston' I must presume???


Ryugen, that "Old Frog" hisself
Ryugen@palaver.org




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