Fw: Layer 3 Switching Flow Mask [7:3360]

[Ronny Jonathan]

- Original Message -
From: Mr. Oletu Hosea Godswill, CCNA 
To: Ronny Jonathan 
Sent: Monday, May 07, 2001 6:18 PM
Subject: Re: Layer 3 Switching Flow Mask [7:3360]


> Me think since MLS has to do with layer 2 up to layer 4. We know that
layer
> 4 has ports numbers and all that. Ordinary if the ports numbers at layer 4
> at not made used of, MLS has not been accomplished. Access-list or
something
> have to be configured so that layer 4 element are used in the decision
> making. Since this is the basic defination of MLS, it then means Flow mask
> is an additional thing.
>
> I agree with what the cisco press book said, if you say
> set mls flow destination
> (only destination informations will be kept in the mls cache)
> or if you say
> set mls flow destination-source
> (both source and destination ip-addresses will be kept in the mls cache)
> better stil
> set mls flow full
> (All informations including port numbers will be documented in the cache)
>
> Good luck,
> (Also preparing for BCMSN)
>
> my 2 cents.
> Oletu
>
>
>
> - Original Message -
> From: Ronny Jonathan 
> To: 
> Sent: Sunday, May 06, 2001 12:10 PM
> Subject: Layer 3 Switching Flow Mask [7:3360]
>
>
> > Hi All,
> >
> > In BCMSN course book (Cisco Press) p233, it is stated that:
> > "Most Cisco documentation explains flow masks as a way to determine how
> > packets are compared to entries in the MLS cache. This is inaccurate.
Flow
> > masks are actually used to determine how much information about the
packet
> is
> > placed in the MLS cache. The flow mask is not used to compare packets to
> > existing entries in the MLS cache"
> >
> > But from another source (Boson & Cisco Doc):
> > "you are introducing policy based routing and want to route differently
> based
> > on source, destination, and port number. What command would you use on a
> > multi-level switch to make it consider port numbers when layer 3
> forwarding ?
> > the correct syntax is: set mls flow
[destination|destination-source|full].
> >
>
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat5000/rel_5_2/layer3/m
> l
> > s.htm#xtocidll0l940"
> >
> > So the command "set mls flow ...", is it only to determine what
> information
> > to
> > be kept in the mls entry or is it meant to enforce so that all packets
> going
> > through the L3 switch will be compared to the mls entry according to the
> flow
> > mask that has been set up by the "set mls flow" command ?
> >
> > Thanks in advance for the answer, I need it for BCMSN exam on Wednesday.
> >
> > Regards,
> > Ronny
> > FAQ, list archives, and subscription info:
> http://www.groupstudy.com/list/cisco.html
> > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
>
>
> _
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RE: Layer 3 Switching Flow Mask [7:3360]

[Ronny Jonathan]

First, thanks for your answer Drew ... but I'm still
confused ...

> It determines what information
> is stored in the mls entry and enforces all packets
> coming through the mls
> switch to be compared with the entry according to
> the flow mask specified
> with set mls flow.
How about the note in the BCMSN course book. My
interpretation for the note is:

The "set mls flow" is to determine what information to
be stored in the mls entry (for statistic and data
collection purpose), but NOT to enforce packets that
go through the mls switch to be compared with the mls
entry according to the flow mask specified by the
command.

> By the way, there is a difference between an L3
> switch and an mls-capable
> switch.  Make sure you don't get those confused.
What is the different ? Are you referring to the
RSM/RSFC/MSM/MSFC (MLS-RP) for the layer 3 switch and
Cat 5000/6000(MLS-SE) for the mls-capable switch ?

Regards,
Ronny

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Layer 3 Switching Flow Mask [7:3360]

[Ronny Jonathan]

Hi All,

In BCMSN course book (Cisco Press) p233, it is stated that:
"Most Cisco documentation explains flow masks as a way to determine how
packets are compared to entries in the MLS cache. This is inaccurate. Flow
masks are actually used to determine how much information about the packet is
placed in the MLS cache. The flow mask is not used to compare packets to
existing entries in the MLS cache"

But from another source (Boson & Cisco Doc):
"you are introducing policy based routing and want to route differently based
on source, destination, and port number. What command would you use on a
multi-level switch to make it consider port numbers when layer 3 forwarding ?
the correct syntax is: set mls flow [destination|destination-source|full].
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat5000/rel_5_2/layer3/ml
s.htm#xtocidll0l940"

So the command "set mls flow ...", is it only to determine what information
to
be kept in the mls entry or is it meant to enforce so that all packets going
through the L3 switch will be compared to the mls entry according to the flow
mask that has been set up by the "set mls flow" command ?

Thanks in advance for the answer, I need it for BCMSN exam on Wednesday.

Regards,
Ronny




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