From: Alexander Arsenyev (GU/ETL) (alexander.arsenyev@ericsson.com)
Date: Sun Jul 18 2004 - 04:20:05 GMT-3
I believe that Cat3550 will ARP for "everything" IF IP address/netmask combination
on VLAN interface covers that "everything". That's why sometimes it's important
to trick Cat3550 into thinking that "everything" is directly connected, see
my earlier post http://www.groupstudy.com/archives/ccielab/200406/msg01843.html
HTH,
Cheers
Alex
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Brian McGahan
Sent: 18 July 2004 01:29
To: Kenneth Wygand; Mike Calhoon; Lord, Chris; ccielab@groupstudy.com
Subject: RE: 3550 COnnectivity
Ken,
Your statements are true to a degree. Technically the 3550 is
not using proxy-arp. Instead, it is just ARPing for everything. It is
the router that responds on behalf of the destination that is being
ARPed for (hence proxy-arp).
I only mention this point because it is the router on the
attached segment that must be running proxy-arp, and not the switch
itself.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Kenneth Wygand
> Sent: Saturday, July 17, 2004 5:23 PM
> To: Mike Calhoon; Lord, Chris; ccielab@groupstudy.com
> Subject: RE: 3550 COnnectivity
>
> Mike,
>
> Without specifying the "ip default-gateway", your 3550 will default to
> using proxy-arp to resolve your IP addresses to MAC addresses. If
your
> attached router (on the VLAN where your switch's IP address is)
supports
> proxy-arp, it will resolve and your ping will succeed.
>
> You should have entries if you do a "show arp" when using proxy-arp,
but I
> don't believe those entries will exist when crossing VLANs if you have
a
> default gateway configured (just your default gateway will be in your
> local arp table).
>
> If you can, try it out both ways and post your outputs! :)
>
> Hope this helps,
> Ken
>
> ________________________________
>
> From: nobody@groupstudy.com on behalf of Mike Calhoon
> Sent: Sat 7/17/2004 6:18 PM
> To: 'Lord, Chris'; ccielab@groupstudy.com
> Subject: RE: 3550 COnnectivity
>
>
>
> Chris,
>
> I have wondered the same thing lately. I have found that as long as
the
> rest of my routers have the route to the VLAN installed, I can ping
the ip
> on the switch without having to add "ip default-gateway", ip routing,
or
> anything else to it. So full connectivity is being reached, but I am
> wondering if I should be adding "ip default-gateway" or anything extra
to
> the switch.
>
>
> Thanks,
> Mike
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Lord, Chris
> Sent: Saturday, July 17, 2004 5:03 PM
> To: ccielab@groupstudy.com
> Subject: 3550 COnnectivity
>
> Please could I ask for some opinions.......
>
> A lot of practice lab scenarios state standard assumptions such as "do
not
> use static or default routes on any router, etc" and "full
connectivity
> must
> be attained, etc". Suppose we met this in the real lab, my question is
> this... if one of the switches has a vlan interface with an ip address
> assigned to it then I assume the pod should be able to ping it and
> vica-versa. If the switch is not running an IGP, is the use of "ip
> default-gateway" permissible or does this break the rules?
>
> If you can't use "ip default-gateway" do you think configuring irdp on
the
> attached router in the switch's management vlan would be a good
> alternative?
>
> thx in anticipation,
>
> Chris.
>
>
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