From: Vincent Mashburn (vmashburn@fedex.com)
Date: Tue Oct 31 2006 - 11:16:30 ART
If I understand your predicament correctly here, you have 2 routers on
the same physical segment, but each router is the gateway to a different
subnet. If this is the case, why not make each router part of both
subnets (via secondary addressing) and then use something like HSRP or
VRRP (using 2 groups) to make Router 1 the primary for subnet 1 and
Router 2 the primary for subnet 2? Just a thought... may be work
trying.
Thanks
Vince Mashburn
Voice / Data Engineer
901-263-5072
CCVP, CCNP, CCDA,Network +
Cisco IP Telephony Support Specialist
Cisco IP Telephony Operations Specialist
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Venkataramanaiah.R
Sent: Tuesday, October 31, 2006 3:01 AM
To: Brian McGahan
Cc: fangbo; Fosket, William; ccielab@groupstudy.com
Subject: Re: Proxy-Arp with two routers on a segment..
Brian is correct.. We tested this with Windows host and it behaves this
way...
However my legacy host some trouble while generating the arp requests,
it always uses the first subnet IP while raising the arp request,
although it owns both subnets on the same NIC. So at all times, Router
of Subnet A is chosen.
Regards
-Venkat
On 10/31/06, Brian McGahan <bmcgahan@internetworkexpert.com> wrote:
> Tim,
>
> Assuming that proxy-ARP is enabled and that the host who
> originates the ARP request has an IP address in the same subnet of the
> interface that the router receives the ARP request on, then yes.
>
> Brian McGahan, CCIE #8593 (R&S/SP)
> bmcgahan@internetworkexpert.com
>
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
> Toll Free: 877-224-8987 x 705
> Outside US: 775-826-4344 x 705
> 24/7 Support: http://forum.internetworkexpert.com
> Live Chat: http://www.internetworkexpert.com/chat/
>
>
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > fangbo
> > Sent: Monday, October 30, 2006 10:33 PM
> > To: Brian McGahan; 'Fosket, William'; 'Venkataramanaiah.R'
> > Cc: ccielab@groupstudy.com
> > Subject: re: Proxy-Arp with two routers on a segment..
> >
> > Hi there,
> >
> > I guess the host will send arp request to broadcast( FFFFFFFFFFFF),
so
> > every
> > routers on same segment will get the request and send arp reply out
if
> he
> > know the route to destination.
> > Is this right?
> > Thanks and regards,
> >
> > tim
> > -----SJ<~T-<~-----
> > 7"<~HK: nobody@groupstudy.com [mailto:nobody@groupstudy.com] 4z1m
> Brian
> > McGahan
> > 7"KMJ1<d: 2006Dj10TB31HU 5:49
> > JU<~HK: Fosket, William; Venkataramanaiah.R
> > 3-KM: ccielab@groupstudy.com
> > VwLb: RE: Proxy-Arp with two routers on a segment..
> >
> > > If an arp request from 1.1.1.2/24 were seen by a router at
> 1.1.1.1/24
> > > and a router at 2.2.2.1/24 on the same segment, would their be any
> > > special configuration required to prevent 2.2.2.1 from answering?
> >
> > No extra configuration is needed. The router at 2.2.2.1/24
will
> > not respond to an ARP from 1.1.1.2 unless Local Area Mobility is
> > enabled.
> >
> > Brian McGahan, CCIE #8593 (R&S/SP)
> > bmcgahan@internetworkexpert.com
> >
> > Internetwork Expert, Inc.
> > http://www.InternetworkExpert.com
> > Toll Free: 877-224-8987 x 705
> > Outside US: 775-826-4344 x 705
> > 24/7 Support: http://forum.internetworkexpert.com
> > Live Chat: http://www.internetworkexpert.com/chat/
> >
> >
> > > -----Original Message-----
> > > From: Fosket, William [mailto:William.Fosket@compass.net]
> > > Sent: Monday, October 30, 2006 3:06 PM
> > > To: Brian McGahan; Venkataramanaiah.R
> > > Cc: ccielab@groupstudy.com
> > > Subject: RE: Proxy-Arp with two routers on a segment..
> > >
> > > It's more of an issue of where the request is coming from than
where
> > > they are trying to get to, I think. It is more a question about
how
> > arp
> > > works than how proxy arp works. Though the requests would come
from
> > the
> > > same segment, they'd be coming from different subnets (if I
> understood
> > > correctly).
> > >
> > > If an arp request from 1.1.1.2/24 were seen by a router at
> 1.1.1.1/24
> > > and a router at 2.2.2.1/24 on the same segment, would their be any
> > > special configuration required to prevent 2.2.2.1 from answering?
> > >
> > > Bill Fosket CCIE #16041
> > >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
Behalf
> > Of
> > > Brian McGahan
> > > Sent: Monday, October 30, 2006 1:47 PM
> > > To: Venkataramanaiah.R
> > > Cc: ccielab@groupstudy.com
> > > Subject: RE: Proxy-Arp with two routers on a segment..
> > >
> > > The ARP request will always come in from a host on a directly
> > > connected segment. If the router has a route to the ARP's
> destination
> > > and proxy-arp is enabled on the connected link that the ARP was
> > received
> > > the router will reply with its own MAC address. The destination
> does
> > > not have to be connected, it just has to be in the routing table.
> > >
> > > Diagram out your topology and let me know exactly what you are
> > > trying to accomplish and I can give you a better recommendation.
> > >
> > >
> > > HTH,
> > >
> > > Brian McGahan, CCIE #8593 (R&S/SP)
> > > bmcgahan@internetworkexpert.com
> > >
> > > Internetwork Expert, Inc.
> > > http://www.InternetworkExpert.com
> > > Toll Free: 877-224-8987 x 705
> > > Outside US: 775-826-4344 x 705
> > > 24/7 Support: http://forum.internetworkexpert.com
> > > Live Chat: http://www.internetworkexpert.com/chat/
> > >
> > >
> > > > -----Original Message-----
> > > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> Behalf
> > > Of
> > > > Venkataramanaiah.R
> > > > Sent: Monday, October 30, 2006 10:59 AM
> > > > To: Brian McGahan
> > > > Cc: ccielab@groupstudy.com
> > > > Subject: Re: Proxy-Arp with two routers on a segment..
> > > >
> > > > Brian, Moreover, you suggestion will apply only if i am proxy
> arping
> > B
> > > > from A and vice versa.. But when i arp any other subnets, both
> > routers
> > > > will have these routers..
> > > >
> > > > In any case, i think bill's understanding with this issue is
> > correct.
> > > > Routers seem to responding only to the connect hosts. (They
verify
> > > > source addresses before responding with MAC). However, in our
> case,
> > > > our legacy hosts, which uses same NIC for both subnets, never
uses
> > > > second subnet to ask for MAC. So always R1 responds..
> > > >
> > > >
> > > >
> > > > On 10/30/06, Venkataramanaiah. R <vramanaiah@gmail.com> wrote:
> > > > > Brian, I like your advise, but i cannot do that, i want this
> > > > > intercommunication to around via both routers..
> > > > >
> > > > > It is a strange topology that we are trying to build upon
here,
> > with
> > > > > legacy telcom hosts. So bear with me for that ;-)
> > > > >
> > > > > thanks
> > > > >
> > > > >
> > > > > On 10/30/06, Brian McGahan <bmcgahan@internetworkexpert.com>
> > wrote:
> > > > > > You will only reply with proxy-arp if you have a route to
the
> > > > requested
> > > > > > host's subnet. Remove router 1's route to subnet 2 and
remove
> > > router
> > > > > > 2's route to subnet 1 and you will see the desired behavior.
> > > > > >
> > > > > >
> > > > > > HTH,
> > > > > >
> > > > > > Brian McGahan, CCIE #8593 (R&S/SP)
> > > > > > bmcgahan@internetworkexpert.com
> > > > > >
> > > > > > Internetwork Expert, Inc.
> > > > > > http://www.InternetworkExpert.com
> > > > > > Toll Free: 877-224-8987 x 705
> > > > > > Outside US: 775-826-4344 x 705
> > > > > > 24/7 Support: http://forum.internetworkexpert.com
> > > > > > Live Chat: http://www.internetworkexpert.com/chat/
> > > > > >
> > > > > >
> > > > > > > -----Original Message-----
> > > > > > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]
> On
> > > Behalf
> > > > > > Of
> > > > > > > Venkataramanaiah.R
> > > > > > > Sent: Saturday, October 28, 2006 1:09 PM
> > > > > > > To: ccielab@groupstudy.com
> > > > > > > Subject: Proxy-Arp with two routers on a segment..
> > > > > > >
> > > > > > > I have a requirement where there will be two routers on
the
> > same
> > > > > > > segment supporting two different subnets... The segments
> have
> > > hosts
> > > > > > > belonging to both these subnets..
> > > > > > >
> > > > > > > I want to enforce the following..
> > > > > > >
> > > > > > > Router 1 must respond to proxy-arp request only from hosts
> > > belonging
> > > > > > > to Subnet 1.
> > > > > > >
> > > > > > > Router 2 must respond to proxy-arp request only from hosts
> > > belonging
> > > > > > > to Subnet 2.
> > > > > > >
> > > > > > > Is there a way out..? I cant think of any way to achieve
> > this,
> > > so
> > > > > > > thought i will ask the experts :-)
> > > > > > >
> > > > > > >
> > > > > > > Regards
> > > > > > > -Venkat
> > > > > > >
> > > > > > >
> > > > > >
> > > >
> > >
> >
>
This archive was generated by hypermail 2.1.4 : Wed Nov 01 2006 - 07:29:07 ART