RE: DLSW peer question

From: Jason Sinclair (sinclairj@xxxxxxxxxxxxxxx)
Date: Thu Nov 01 2001 - 22:56:36 GMT-3


   
Jim,

Guess it comes back to horses for courses again. Let's face it - in the lab
they will ask for wacky things so I guess anything goes if it answers the
question! In real life, however it may be totally different. Cisco always
says there is no one right way!

Cheers,
Jason Sinclair
Network Support Manager
POWERTEL Limited
Level 11, 55 Clarence Street, SYDNEY
Phone: 61-2-8264-3820
Fax: 61-2-9279-2604
Mobile: 0416 105 858
jasons@powertel.net.au

                -----Original Message-----
                From: Jim Brown [mailto:Jim.Brown@CaseLogic.com]
                Sent: Friday, 2 November 2001 10:49
                To: 'Jason Sinclair'; 'fwells12'; Jim Brown;
ccielab@groupstudy.com
                Subject: RE: DLSW peer question

                Imagine this.... you are peering between sites 'A' and 'B'
using loopbacks
                across a WAN link. The Ethernet port at site 'A' fails. Site
'B' will
                continue to send data across the WAN link. From the
perspective of site 'B'
                everything is OK because the DLSW connection is maintained
between
                loopbacks.

                The DLSW connection is completely unaware of the fact that
the data has
                nowhere to go once it arrives at site 'A'. I don't believe
DLSW monitors the
                availably of interfaces attached to the ring group/bridge
group.

                Using the same scenario except we peer between the Ethernet
ports. If one of
                the Ethernet ports fail, the DLSW connection is torn down
conserving our
                precious WAN bandwidth.

                This is my reasoning why it is better to peer between
physical interfaces in
                certain circumstances. All bets are off with two physical
interfaces on the
                same router participating in DLSW. You could potentially
tear down the
                connection when only one of the interfaces fails and leave
the other segment
                on the same router out in the cold.

                I'm only speaking of theory. I might be way off my rocker.
I've never used
                DLSW in a production environment. So clarification of my
ramblings are
                welcomed. If a DLSW guru wants to straighten me out I'm all
ears.

                -----Original Message-----
                From: Jason Sinclair [mailto:sinclairj@powertel.com.au]
                Sent: Thursday, November 01, 2001 6:27 PM
                To: 'fwells12'; Jim Brown; ccielab@groupstudy.com
                Subject: RE: DLSW peer question

                However,

                Based on the logic of single interfaces, if the single
interface were to
                fail (and they were directly connected!) the a side wouldn't
send anyway as
                layer 2 would have failed?

                Regards,

                Jason Sinclair
                Network Support Manager
                POWERTEL Limited
                Level 11, 55 Clarence Street, SYDNEY
                Phone: 61-2-8264-3820
                Fax: 61-2-9279-2604
                Mobile: 0416 105 858
                jasons@powertel.net.au

                                -----Original Message-----
                                From: fwells12
[mailto:fwells12@hotmail.com]
                                Sent: Friday, 2 November 2001 10:02
                                To: Jim Brown; ccielab@groupstudy.com
                                Subject: Re: DLSW peer question

                                Good point.

                                ----- Original Message -----
                                From: "Jim Brown" <Jim.Brown@CaseLogic.com>
                                To: "'Geir Jensen'" <geir@hfk.vgs.no>;
"fwells12"
                <fwells12@hotmail.com>;
                                <ccielab@groupstudy.com>
                                Sent: Thursday, November 01, 2001 1:45 PM
                                Subject: RE: DLSW peer question

> In a production environment would it not
make more sense
                to tie the local
> peer to a single physical interface if
there is only one
                interface
> participating in DLSW?
>
> If it is tied to the physical interface,
when it goes down
                then so does
                                the
> DLSW connection.
>
> If it is tied to a loopback and the
physical interface is
                down, DLSW
                                traffic
> will travel to the remote end only to be
dropped.
>
> It seems to me tying it to the physical
interface would
                conserve bandwidth
> during interface failures.
>
>
> -----Original Message-----
> From: Geir Jensen [mailto:geir@hfk.vgs.no]
> Sent: Thursday, November 01, 2001 2:16 PM
> To: fwells12; ccielab@groupstudy.com
> Subject: RE: DLSW peer question
>
>
> I always use the loopback, it's definately
more stable
                than the
> alternatives. Geir Jensen
>
> -----Original Message-----
> From: fwells12
> Sent: Thu 11/1/2001 9:34 PM
> To: ccielab@groupstudy.com
> Cc:
> Subject: DLSW peer question
>
>
>
> OK, you have a router which has more than
one LAN
                interface it needs
> DLSW
> traffic forwarded from, let's say e0 and
t0. It also has
                a loopback
> int with
> ip ad 172.16.10.1/24. The ip's of the e0
and t0
                interfaces are
> 172.16.20.1/24
> and 172.16.30.1/24 respectively. What ip
address is the
                best
> practice to use
> for your dlsw local-peer peer-id
statement?
>
> Cheers
                        
        



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