From: Jayashanker Warrier (jwarrier@rediffmail.com)
Date: Thu Oct 10 2002 - 05:08:36 GMT-3
Hi Nick,
Even RTP kick in only when there is a congestion so the only
option is RSVP (please correct me if i am wrong)
Thanks
Jayashanker
At 07:35 10/10/2002 +1000, Nick Shah wrote:
Ok, The reason LLQ or CBWFQ doesnt satisfy the requirements is
because :
- Remember CBWFQ kicks in only when there is congestion, so if you
specify
40K b/w for class voice, that only comes into affect when there
is
congestion
- When there is no congestion, VOICE traffic is free to use as
much as it
'demand'
- HEnce the Lab requirement of using 40KMax is not fulfilled.
- Here's where RSVP reservation or IP RTP comes into play. because
it uses
either 40K or nothing it is the ideal choice.
rgds
Nick
----- Original Message -----
From: Jaroslaw Zak <jaroslawz@hotmail.com>
To: <clarson52@comcast.net>; <nshah@connect.com.au>;
<CLarson@usaid.gov>;
<ccielab@groupstudy.com>
Sent: Thursday, October 10, 2002 1:18 AM
Subject: Re: RSVP
>Chris,
>
>For this particular question, how about LLQ, where you do
>configure
priority
>queue for voice and specify minimum bandwidth (no need for ip
>rtp) and you
>can apply it per interface or per pvc, and you dont have to apply
>that all
>the way end-to-end (which is just a bad design anyway, but
>satisfies your
>task).
>
>Regards
>Jarek
>
>
> >From: Chris <clarson52@comcast.net>
> >Reply-To: Chris <clarson52@comcast.net>
> >To: Nick Shah <nshah@connect.com.au>, "Larson, Chris"
<CLarson@usaid.gov>,
> > ccielab@groupstudy.com
> >Subject: Re: RSVP
> >Date: Wed, 09 Oct 2002 06:53:17 -0400
> >
> >First, thanks for your reply. I appreciate it. My post was more
>of a rant
I
> >spose.
> > I am not really confused about the technology. I understand
>RSVP,
CBWFQ,
> >WRED etc. etc.
> >
> >My post was mostly written out of frustration and confusion
>with the lab
> >authors questions and maybe labs in general. As stated before
>the
question
> >was not real clear excpet to make 40k available to voice. Well
>anyone who
> >understands the technology would drop RSVP right away because
>it is not
> >configured anywhere else and therefore configuring it on this
>one
interface
> >doesn't make sense and w/o going back to look at the lab prolly
>wouldn't
> >meet the requirement as putting it on this one interface does
>not make
40k
> >available to voice.
> >
> >This is my problem with a lot of lab questions. The fact that a
>lot of
them
> >are far from reality. I can catch the subtle hints at what the
>author
wants
> >at times but some are so vague.
> >
> >Here is another example. R3 and R4 are running ospf. They are
>part of a
> >larger network of course. On R3 and R4 there is serial and
>isdn. On R3
> >ensure that if the connection to R4 is lost that R3 can still
>communicate
> >with the rest of the network? What the hell is that? Since it
>is in OSPF
> >well a loss of ospf on either router will keep R3 from
>communicating with
> >the rest of the network. Having built a lot of networks in the
>real world
I
> >would be inclined to do a demand circuit. However, the answer
>was a
backup
> >interface. The way it is configured would not allow it to
>communicate
with
> >the rest of the network, only with R4 (unless a default route
>was added).
> >I
> >know..... I KNow.... it is a test to see if you understand the
>technology
> >not if you know how to use it well.
> >I would suggest they move that stuff into the written and
>expect a CCIE
> >candidate to configure things that work and that would be
>acceptable to
the
> >real world.
> >
> >Sorry, just a rant and I am done now. In my opinoin the real
>lab is much
> >less vague then some of these practice ones I have found
>anyway. Thank
> >goodness.
> >
> >
> >
> >----- Original Message -----
> >From: "Nick Shah" <nshah@connect.com.au>
> >To: "Larson, Chris" <CLarson@usaid.gov>;
><ccielab@groupstudy.com>
> >Sent: Tuesday, October 08, 2002 10:54 PM
> >Subject: Re: RSVP
> >
> >
> > > Chris,
> > >
> > > You are right. I guess we should be lookign at the wording
>of the
> >question.
> > > That would be a giveaway. Plus our understanding of the
>underlying
> > > technology.
> > >
> > > For example. CBWFQ doesnt kick in until there is a
>congestion, when
> >there
> >is
> > > a congestion you get the specified b/w (specified in the
class/policy).
> >It
> > > also doesnt take care of serialization delay, jitter (what
>if the
> >interface
> > > is transmitting a large packet just around the time your
>voice packet
> >comes
> > > in, voice packet waits).
> > >
> > > With RSVP, the required b/w is signalled at the beginning of
>the
> > > conversation, if required b/w is not available tough luck,
>no call
made.
> > > This reservation is made end to end. And you may also need
>to specify
> > > 'req-qos guaranteed delay or req-qos controlled load' under
>dial
peers.
> > >
> > > With RTP priority, you use it when you are asked to
>strictly
prioritise
> > > voice and all else use CQ or WFQ. so you specify ip rtp
>priority
<port>
> > > <port> bw. Use it when you have to prioritise VOICE above
>all others.
> > >
> > > And then there is frame relay fragmentation , if data &
>voice traffic
> >takes
> > > a single PVC path.
> > > or DLCI prioritization along with PQ if using different
>PVC;s for
> > > VOICE/DATA/whatever else.
> > >
> > > Plus remember where the technologies can be implemented, on
>the edge
or
> >in
> > > the core, for TCP or UDP. Like WRED can be used for TCP (TCP
>"adapts",
> >UDP
> > > doesnt), but for UDP its not really helpful.
> > >
> > > We can virtually use any/every queuing technology depending
>on a
> >scenario.
> > > (WFQ even). It will all depend upon the wording of the
>question and
what
> >is
> > > allowed/expected/disallowed etc.
> > >
> > > Hope, I have not confused you more :) than you already
>were.
> > >
> > > BTW, in your question, you cant use CBWFQ because the
>specified b/w in
> >cbwfq
> > > is 'minimum' amount of b/w usable during congestion, so rule
>it out of
> > > equation.
> > >
> > > You could use either RSVP or RTP.
> > >
> > > rgds
> > > Nick
> > >
> > >
> > > ----- Original Message -----
> > > From: "Larson, Chris" <CLarson@usaid.gov>
> > > To: <ccielab@groupstudy.com>
> > > Sent: Wednesday, October 09, 2002 12:13 AM
> > > Subject: RSVP
> > >
> > >
> > > > I had a question in a lab scenario that called to make 40
>k
available
> >to
> > > > voice traffic. My first thought was ip rtp priority with a
>40k max
> >limit.
> > > > However the solution calls for RSVP.
> > > >
> > > > Nowhere else is RSVP configured. Based on what I know
>about RSVP
this
> > > could
> > > > not be correct. RSVP requires configuration all along the
>paths
right?
> >How
> > > > would a person determine they are asking for RSVP? For
>that matter
how
> > > would
> > > > you know if they are asking for CBWFQ? It could be used
>to
accomplish
> >the
> > > > same thing if the acl were setup rightin the class map?
> > > >
> > > > I would think that if a solution called for RSVP the
>question would
> >state
> > > to
> > > > reserve a certain amount of bandwidth, not make available.
>Thoughts?
> >How
> > > to
> > > > determine what a given question wants in the way of QoS.
> > > >
> > > >
> > > >
> > > >
> > > > Christopher Larson - CNE, MCP+I, CCNP + Security
> > > > Open Systems Sciences Corp.
> > > > USAID Information Resources Management (contractor)
> > > > 202 712 4559
> > > > clarson@usaid.gov
>
>
>
>
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