From: Larry Letterman (lletterm@cisco.com)
Date: Thu May 05 2005 - 22:29:02 GMT-3
in my mind, its one and the same..however Howard and Priscilla will
write a page on it for you..For most of us switching means the packet goes
from
port A to port B in hardware asics..which is faster..forwarding to me means
a host,
switch or router moves the packet from an incoming port to and outgoing port
and can either
be done in the hardware or by a software algorithm..( process switched)
############################
Larry Letterman
Cisco Systems
############################
----- Original Message -----
From: "John Matus" <john_matus@hotmail.com>
To: <lletterm@cisco.com>; <bdennis@internetworkexpert.com>;
<ccielab@groupstudy.com>
Sent: Thursday, May 05, 2005 7:52 PM
Subject: Re: ip helper-address command
> so then what exactly is the difference between switching and forwarding,
if
> they are both layer-2 methods of getting traffic from 1 port to another?
>
> >From: "Larry Letterman" <lletterm@cisco.com>
> >To: "John Matus" <john_matus@hotmail.com>,
> ><bdennis@internetworkexpert.com>, <ccielab@groupstudy.com>
> >Subject: Re: ip helper-address command
> >Date: Thu, 5 May 2005 19:48:47 -0500
> >
> >I personally consider forwarding a layer 2 task which moves the
data/packet
> >from port 1 to
> >port 2 in a switch or router port..routing uses a route lookup table to
get
> >the packet to the next hop
> >address and then forwards the packet to the correct interface..
> >
> >############################
> >Larry Letterman
> >Cisco Systems
> >############################
> >----- Original Message -----
> >From: "John Matus" <john_matus@hotmail.com>
> >To: <bdennis@internetworkexpert.com>; <ccielab@groupstudy.com>
> >Sent: Thursday, May 05, 2005 7:32 PM
> >Subject: RE: ip helper-address command
> >
> >
> > > hmmm........not sure i understand the difference between routing and
> > > forwarding....perhaps forwarding does not use the routing table for
it's
> > > decistion......<i dunno!!!> maybe they should change the test to the
R
> >&
> >S
> > > & F exam.
> > >
> > > >From: "Brian Dennis" <bdennis@internetworkexpert.com>
> > > >To: "John Matus" <john_matus@hotmail.com>,<ccielab@groupstudy.com>
> > > >Subject: RE: ip helper-address command
> > > >Date: Thu, 5 May 2005 20:12:20 -0400
> > > >
> > > >John,
> > > > The helper command is telling the router where to FORWARD the
> > > >packets not ROUTE the packets. Routing and forwarding are two
totally
> > > >different things.
> > > >
> > > >Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
> > > >
> > > >bdennis@internetworkexpert.com
> > > >Internetwork Expert, Inc.
> > > >http://www.InternetworkExpert.com
> > > >Toll Free: 877-224-8987
> > > >Direct: 775-745-6404 (Outside the US and Canada)
> > > >
> > > >-----Original Message-----
> > > >From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> > > >John Matus
> > > >Sent: Thursday, May 05, 2005 4:45 PM
> > > >To: Brian Dennis; ccielab@groupstudy.com
> > > >Subject: RE: ip helper-address command
> > > >
> > > >hmmm......how and why would a router forward udp ports for netbios if
> > > >netbios is a non-routable protocol??
> > > >
> > > > >From: "Brian Dennis" <bdennis@internetworkexpert.com>
> > > > >To: "John Matus" <john_matus@hotmail.com>,<ccielab@groupstudy.com>
> > > > >Subject: RE: ip helper-address command
> > > > >Date: Thu, 5 May 2005 19:38:28 -0400
> > > > >
> > > > >Key is to just know what you are trying to forward. The router
will
> > > > >forward these UDP ports by default:
> > > > >
> > > > >37 Time Protocol
> > > > >49 TACACS
> > > > >53 DNS
> > > > >68 BootP Server
> > > > >69 TFTP
> > > > >137 NetBios
> > > > >138 NetBios Datagram
> > > > >
> > > > >If you want to forward any other UDP ports, you should specify them
> > > >with
> > > > >the "ip forward-protocol udp <port number>" command. If you do not
> > > >want
> > > > >the router to forward any of the default ports, use the "no ip
> > > > >forward-protocol udp <port number>" command.
> > > > >
> > > > >Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
> > > > >
> > > > >bdennis@internetworkexpert.com
> > > > >Internetwork Expert, Inc.
> > > > >http://www.InternetworkExpert.com
> > > > >Toll Free: 877-224-8987
> > > > >Direct: 775-745-6404 (Outside the US and Canada)
> > > > >
> > > > >-----Original Message-----
> > > > >From: John Matus [mailto:john_matus@hotmail.com]
> > > > >Sent: Thursday, May 05, 2005 4:15 PM
> > > > >To: Brian Dennis; ccielab@groupstudy.com
> > > > >Subject: RE: ip helper-address command
> > > > >
> > > > >yes, that is an ugly document indeed. so it looks like the answer
is
> > > > >"no"
> > > > >unless you're running lots of routers that are processing multiple
> > > > >duplicate
> > > > >broadcast request.
> > > > >
> > > > > >From: "Brian Dennis" <bdennis@internetworkexpert.com>
> > > > > >To: "John Matus"
<john_matus@hotmail.com>,<ccielab@groupstudy.com>
> > > > > >Subject: RE: ip helper-address command
> > > > > >Date: Thu, 5 May 2005 18:50:44 -0400
> > > > > >
> > > > > >Everything you ever wanted to know about the "ip helper-address"
> >and
> > > > >"ip
> > > > > >forward-protocol udp" commands but were afraid to ask:
> > > > > >
> > > > > >http://www.cisco.com/univercd/cc/td/doc/cisintwk/idg4/nd2019.htm
> > > > > >
> > > > > >Direct from the DocCD ;-)
> > > > > >
> > > > > >Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
> > > > > >
> > > > > >bdennis@internetworkexpert.com
> > > > > >Internetwork Expert, Inc.
> > > > > >http://www.InternetworkExpert.com
> > > > > >Toll Free: 877-224-8987
> > > > > >Direct: 775-745-6404 (Outside the US and Canada)
> > > > > >
> > > > > >-----Original Message-----
> > > > > >From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> >Behalf
> > > >Of
> > > > > >John Matus
> > > > > >Sent: Thursday, May 05, 2005 2:54 PM
> > > > > >To: ccielab@groupstudy.com
> > > > > >Subject: ip helper-address command
> > > > > >
> > > > > >does the "ip helper-address" command need the "ip
forward-protocol
> > > >udp"
> > > > > >command in order to work correctly?
> > > > > >
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