From: Donghai Zhang (zdh1207@gmail.com)
Date: Tue Sep 18 2007 - 02:43:46 ART
Dear Rik,
I thought I have conceived your second last reply in which you seamed to
have implied that if I use HSRP,then no sub-optimal pathes exit,because the
active gateway would be the switch to which a host is connected. If I want,
no hosts would get a sub-optimal path. Isn't it?
However,what I want to mention here is that: Even using HSRP has nothing
to do with my problem. HSRP is used to solve the problem of gateway
redundency.Let's say, if I set one ip(for ex.192.168.1.1) to the SVI of
vlan10 on SW1 as the gateway of those hosts connecting directly to SW1,
and another ip (for ex. 192.168.1.2) to the SVI of vlan 10 on SW2 as gateway
of those hosts connecting directly to SW2. No sub-optimal path occur, though
it is strange to set two different gateways for a vlan. But it works, and,
with HSRP, it works better.
Let return to your saying. You meant if there's a trunk link between the
two switches then the traffic couldn't take a sub-optimal path. Actually it
still has a sub-optimal path if you fail to properply set the gateways on
each swith, and this time,apparentely,traffic just cross between 3560 ,not
through 4506.
I would like to conclude that : No necessarily need HSRP, no necessarily
need physical link between 3560s, what's needed is two different IP
addresses on each 3560's SVI.
Expecting your comments.thanks.
2007/9/18, Guyler, Rik <rguyler@shp-dayton.org>:
>
> Here's the catch - if you don't put in that trunk link between the two
> switches then the traffic really could take a sub-optimal path. Let's say
> sw1 is active for vlan1/pc1 and sw2 is active for vlan2/pc2. If pc2 is
> connected to sw1, the data from pc2 would have to go all the way up to the
> 4506, back down to sw2, then back up to the 4506 and possibly back to sw1
> if
> vlan is the destination. That is a very sub-optimal method for moving
> data.
>
>
> If your traffic load isn't high then the end-users may never experience a
> serious performance lag but if there will be a lot of traffic on these
> switches then I think you should really consider spending a few more
> dollars
> to make this right. Design work is often times the standing up and
> screaming about how to do things the right way and not cutting corners for
> a
> few dollars here and there.
>
> Do you have any sort of cabling that runs between the two switches?
>
> Rik
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Donghai Zhang
> Sent: Monday, September 17, 2007 9:53 AM
> To: Navid Daghighi
> Cc: ccielab@groupstudy.com
> Subject: Re: where to set the default gateway?
>
> Hi ,dear Rik,you gave me a very detail explanation.thank you very much.Asto
> the trunk link between the two 3560s, I think is not so necessary because
> this link is hard to deployed (distance is too long ,need extra investment
> ,etc), and, trunk between each 3560 and 4506 would also relay vlans as
> well.Your other suggestions are great.
>
> 2007/9/17, Navid Daghighi <daghighi.navid@free.fr>:
> >
> > hi Donghai,
> >
> > why not use HSRP or VRRP ?
> >
> > my little 2 cents...
> >
> > Navid
> >
> >
> > Donghai Zhang a icrit :
> > > the topology may look like this:
> > >
> > >
> > >
> > > ---------
> > > | 4506 |
> > > -----------
> > > / \
> > > / \
> > > / \
> > > --------- ----------
> > > 3560 1 35602
> > > --------- ----------
> > > | | | |
> > > pc1 pc2 PCs
> > >
> > > suppose pc1 in vlan 10 and pc2 in vlan 20,which 3560 acts as the
> > gateway?
> > > if 35602 acts as the getway,should pc1 go through 35601 and then
> > > 4506
> > and
> > > then 35602 and then return along the same route and then back
> > > 35601,and then finally reach pc2? That seams to be apparently
> > > unresonable. But
> > how to
> > > solve it ? You may set gateway just on 35601,but what about PCs
> > > under
> > 35602?
> > > Don't they encounter the same situation?
> > >
> > >
> > > 2007/9/17, Alexander Belov <abelov@technoserv.ru>:
> > >
> > >> Can You draw ? :)
> > >>
> > >> From the bottom story I got You Have 2 (two) distribution layer
> > >> Switches...
> > >> i.e. 2 x 3560...
> > >> Or You are saying You have two 3560s acting as one switch (like a
> > >> cluster)?
> > >> :)
> > >>
> > >> WBR,
> > >> Alex
> > >>
> > >> -----Original Message-----
> > >> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> > >> Behalf Of Donghai Zhang
> > >> Sent: Monday, September 17, 2007 3:01 PM
> > >> To: Marc La Porte
> > >> Cc: ccielab@groupstudy.com
> > >> Subject: Re: where to set the default gateway?
> > >>
> > >> Maybe I was not telling this clearly. I mean I need one of the
> > >> 3560s to
> > be
> > >> the gateway of the PCs in the local LAN. No that there are two
> > >> 3560s, which one would be proper?
> > >>
> > >> 2007/9/17, Marc La Porte <marc.a.laporte@gmail.com>:
> > >>
> > >>> You only have to put a default-gateway on a layer 2 switch, so if
> > >>> both 3560s are layer 3 then it's not necessary on there
> > >>>
> > >>> On 9/17/07, Donghai Zhang <zdh1207@gmail.com> wrote:
> > >>>
> > >>>> Actually the distribute switches will be L3 at this moment. And
> > >>>> the 3560s would be the default gateways of the hosts.The problem
> > >>>> is which 3560 to set ?
> > >>>>
> > >>>> 2007/9/17, Marc La Porte <marc.a.laporte@gmail.com>:
> > >>>>
> > >>>>> Assuming that the core switch will be L3 and the distribution
> > >>>>>
> > >> switches
> > >>
> > >>>>> L2, I would put the SVI on the core switch and the default
> > >>>>> gateway
> > >>>>>
> > >> on
> > >> the
> > >>
> > >>>>> distribution switches
> > >>>>>
> > >>>>> On 9/17/07, Donghai Zhang <zdh1207@gmail.com > wrote:
> > >>>>>
> > >>>>>> Dear all,
> > >>>>>> I have got a problem recently. Suppose I have two catalyst
> > >>>>>> 3560,
> > >>>>>>
> > >> as
> > >>
> > >>>>>> distribute switch, one catalyst 4506,as core switch. I need to
> > >>>>>> set default-gateways of those hosts inside local LAN in the
> > >>>>>>
> > >> 3560s.Theploblem is
> > >>
> > >>>>>> that: in which 3560 should I set the SVI interface? If I set in
> > >>>>>>
> > >> one,
> > >>
> > >>>>>> then
> > >>>>>> the hosts within the same vlan but connecting to the other
> > >>>>>> switch have to travel to this switch so that they can be
> > >>>>>> servced routing,thus bandwith would be waste.
> > >>>>>> Anyone help me ,thanks advance.
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>>
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