Think of the RSM as a router that just happens to be inside a big switch.
It can run routing protocols (OSPF, EIGRP) just like an external router can,
which means it can make routing decisions without the aid of an external
router. This also means it can make the initial routing decision for MLS
and from then on the switch can start forwarding packets.
/Jared
-----Original Message-----
From: Jeffrey Humphreys
To: Odom, Sean/SAC; 'Frank Wells'; [EMAIL PROTECTED]
Sent: 8/12/00 10:53 PM
Subject: Re: Switches !!!
Sean,
I'm confused. Are you saying that if I have a Catalyst 5500 with a RSP
that I will need an additional router (external to the 5500) to route
between VLANs. If that's what your saying, I would have to disagree. I
could do some additional research on it, but I want to ensure that is
what
you are saying.
I believe that the RSP is really just a 7500 and we are running a full
blown
IOS on it to boot. When I do a sho ip ro, I am seeing the local routing
table.
Thanks,
Jeff Humphreys
----- Original Message -----
From: Odom, Sean/SAC <[EMAIL PROTECTED]>
To: 'Frank Wells' <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Friday, August 11, 2000 12:03 PM
Subject: RE: Switches !!!
> Fred
> Switches even with an internal route processor cannot take the place
of a
> router. The first packet in Multilayer switching is resolved by the
> external router. The internal route processor learns from the
forwarding
> decision made by the external router and then uses that resolution for
the
> remainder of the flow from the source to the destination without using
the
> external route processor. Unless the external route router must be
used
as
> a gateway to leave the local boundaries. To answer your question, a
> switched network must still use an external router for Layer 3
resolution.
> Switches using Layer 3 modules merely releive the router of precious
> processing power. Hope this helps. I have two books on switching
which
can
> be used to answer your questions. Visit my website
> www.TheQuestForCertification.Com. -Sean
>
> >Sean Odom, CCNP, MCSE, CNX-EtherII, Author, Instructor
> >GlobalNet Training Solutions
> >[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
> >www.TheQuestForCertication.Com
<http://www.TheQuestForCertication.Com>
>
> -----Original Message-----
> From: Frank Wells [mailto:[EMAIL PROTECTED]]
> Sent: August 11, 2000 9:30 AM
> To: [EMAIL PROTECTED]
> Subject: RE: Switches !!!
>
>
> Hey Sean.
> This is regarding the following passage taken from the your previous
reply
> to this thread:
>
> If C. If the destination and source node reside on ports assigned to
> different VLANs on the switch, the switch requires an external router
to
> resolve the address and send the packet back to the switch. <*** If
the
> switch contains an internal route processor, the external router needs
to
> only resolve the first packet and then the internal route processor
can
> finish the job from there. ***> (An external router needs to be used
so
that
>
> a routing protocol can be used to map the network topology to base
it's
> routes.)
>
> The second sentence implies that there will always need to be at least
one
> router in any switched network. Is this actually correct? I seem to
> remember reading that there are fully switched networks utilizing
layer
> three switching as the routing mechanism. What I am getting at is I
thought
>
> Route Switch Processors are layer three devices and fully capable of
making
> their own routing decisions, in which case there would be no need for
a
> router. Can you shed some more light please.
>
> Thanks a lot.
>
>
> >From: "Odom, Sean/SAC" <[EMAIL PROTECTED]>
> >Reply-To: "Odom, Sean/SAC" <[EMAIL PROTECTED]>
> >To: "'[EMAIL PROTECTED]'" <[EMAIL PROTECTED]>
> >CC: "'Raees Ahmed Shaikh'" <[EMAIL PROTECTED]>
> >Subject: RE: Switches !!!
> >Date: Fri, 11 Aug 2000 09:46:12 -0600
> >
> >a1. How are MAC addresses used on a switch: The MAC address of the
switch,
> >depending on the interface being used, handle this in different ways.
Some
> >Catalyst switches assign a global MAC address, some switches use a
pool
of
> >addresses assigning one to each interface(You can assign one
manually),
and
> >sometimes the MAC address can be a virtual MAC address when using
HSRP on
> >mulitiple internal route processors such as the MSM, RSM, RSFC, NFFC,
> >NFFCII
> >or the MSFC. The switch is assigned an IP address and default
gateway
> >which
> >allows you to telnet to the switch. On most switches you can also
use
the
> >your webrowser to access the switches configuration and make changes
simply
> >by typing in the switches IP address.
> >
> >a2. If two nodes on the same switch want to communicate on the same
switch:
> >(This question requires a long answer!)
> >
> >If: A. They are connected to the same port on the switch the switch
does
> >nothing since the two nodes are in the same collision domain they
will
see
> >each others traffic.
> >
> >If B. They are in the same VLAN and reside on the same switch, the
switch
> >learns the location of each node attached by reading the first frame
> >received and logging the source address and port of arrival in it's
Content
> >Addressable Memory(CAM) table. When the switch receives another frame
it
> >checks the CAM table and if it knows the port the destination node
resides
> >on it forwards the frame directly to that port. If it does not know
the
> >port, it broadcasts the frame to every port which are members of the
same
> >VLAN with the exception to the port of arrival.
> >
> >If C. If the destination and source node reside on ports assigned to
> >different VLANs on the switch, the switch requires an external
router to
> >resolve the address and send the packet back to the switch. If the
switch
> >contains an internal route processor, the external router needs to
only
> >resolve the first packet and then the internal route processor can
finish
> >the job from there. (An external router needs to be used so that a
routing
> >protocol can be used to map the network topology to base it's
routes.)
> >
> >Hope this answers your questions.
> >
> >Sean Odom, CCNP, MCSE, CNX-EtherII, Author, Instructor
> >GlobalNet Training Solutions
> >[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
> >www.TheQuestForCertication.Com
<http://www.TheQuestForCertication.Com>
> > -----Original Message-----
> >From: Raees Ahmed Shaikh [mailto:[EMAIL PROTECTED]]
> >Sent: August 08, 2000 11:50 PM
> >To: '[EMAIL PROTECTED]'
> >Subject: Switches !!!
> >
> >
> >
> >
> > If all the ports of the switches have mac addresses than
> >
> >q.1 If somebody telnets to swithes the actual physical communication
> >occurs
> >through which mac address.
> >q.2 If two pcs are connected to the same swithc, and they want to
> >communicate the real communication should go like this ( pc mac-
switch
> >port mac - destination switch port mac - destination pc).
> >
> >Totally confused arp arp arp.
> >
> >Please Help.
> >
> >
> >Shaikh Raees Ahmed,
> >Microsoft Certified Systems Engineer,
> >Systems & Network,
> >IT Division.
> >
> >___________________________________
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>
>
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