Subject: Please help me for this rsvp questions, thanks

From: "Hong Liao" <[email-masked]>
Date: Tue, 6 Nov 2001 11:15:16 -0500

Hi,

PathErr/ResvErr is optional not for the RFC2205 Appendix B,

For example:   rsvp spec rfc 2205 page 62

            One might expect the known Class-Num to provide information
           that could allow intelligent handling of such an object.
           However, in practice such class-dependent handling is
           complex, and in many cases it is not useful.

           Generally, the appearance of an object with unknown C-Type
           should result in rejection of the entire message and
           generation of an error message (ResvErr or PathErr as
           appropriate).  The error message will include the Class-Num
           and C-Type that failed (see Appendix B); the end system that
           originated the failed message may be able to use this
           information to retry the request using a different C-Type
           object, repeating this process until it runs out of
           alternatives or succeeds.

FRC2119

SHOULD   This word, or the adjective "RECOMMENDED", mean that there
   may exist valid reasons in particular circumstances to ignore a
   particular item, but the full implications must be understood and
   carefully weighed before choosing a different course.

It looks like the Should means patherr or resverr is optional when the path
or resv message with error was sent out, the patherr or resverr is optioanl
to be sent back from switch.

Can anyone comfirm this for me?

Thanks a lot for your help.

Julia

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From: Swayam Prakash <[email-masked]>
Date: Wed, 07 Nov 2001 09:21:29 +0530

Julia,

Both the error messages are not optional, they r must. If there are no error
messages , for eg. the sender will be forever sending path message in wrong
format ,periodically.
I feel you are looking too much into the words like 'should'.
what should means there is that if errors messages are not issued, there should
be some other means of performing a similar action(notifying the sender that
path message is sent in wrong format)

the definition of should itself says :

*******but the full implications must be understood and
   carefully weighed before choosing a different course.************

Any RFC is not a standard. Its upto the person whether any particular feature
is implemented are not.
RFC gives one way of implementing, if anybody  wants to deviate from the RFC
one should be able to see the repercussions of the same.

Others, correct me if iam wrong.

Thanks
-Swayam

---

From: Kiran Kumar A <[email-masked]>
Date: Wed, 07 Nov 2001 09:26:54 +0530

Hi Hong Liao,
                I hope PathErr and RecvErr messages are OPTIONAL.
The reason is.............

1. If there is an error in Path msg then the very first RSVP router which
receives
    that Path msg will stop forwarding the Path msg further. As a result, the
    receiver will not receive the Path msg and so there is no scope of
generating
    the corresponding Recv msg. At the same time, the timeout will occur at
the
    Sender side as it didn't received any corresponding Resv msg. Then the
Sender
    will again send the Path msg.

2. If there is an error in Resv msg then the very first RSVP router which
receives
    that Resv msg will stop forwarding the Resv msg. As a result, the Sender
will
    not receive any Recv msg for that Path msg and timeout will occur at
Sender
    side. At the Receiver side also timeout will occur for the Resv msg as it
won't
    get any Recv refresh msg with in the time and the corresponding Receive
state
    block is deleted.
          In this case, as the Sender didn't received any Recv msg within the
    timeout, anyhow Path refresh msg will be send to the receiver. Then a new
Recv
    msg is sent to the sender.

Please acknowlege to this answer (whether it is right or wrong) ...........

--
Thanx and regards,

 __/__/__/__/__/__/__/__/__/__/__/__/__/__/__/
         __/
        __/   Kiran Kumar Alampally
       __/   Software Engineer
      __/   Rendezous On Chip
     __/   Banjara Hills, Hyderabad.
    __/   Off:: 3351175/84 extn-303
   __/   Res:: 3526313
  __/   @:: [email-masked]

---

From: Swayam Prakash <[email-masked]>
Date: Wed, 07 Nov 2001 10:41:41 +0530

-------------c inline---------

Kiran Kumar A wrote:

> 1. If there is an error in Path msg then the very first RSVP router
> which receives
>     the corresponding Recv msg. At the same time, the timeout will
> occur at the
>     Sender side as it didn't received any corresponding Resv msg. Then
> the Sender

what happens when the sender sends the same path message(with wrong
format) again.
this will go forever
the sender should know that there is some error in format of sending
path message,which happens thro patherr mesg;.

>
> 2. If there is an error in Resv msg then the very first RSVP router
> which receives
>     that Resv msg will stop forwarding the Resv msg. As a result, the
> Sender will
>     not receive any Recv msg for that Path msg and timeout will occur
> at Sender
>     side. At the Receiver side also timeout will occur for the Resv
> msg as it won't
>     get any Recv refresh msg with in the time and the corresponding
> Receive state
>     block is deleted.
>     timeout, anyhow Path refresh msg will be send to the receiver.
> Then a new Recv

---

From: Swayam Prakash <[email-masked]>
Date: Wed, 07 Nov 2001 11:55:12 +0530

Hi
I have a doubt regarding the tockenbucket model.

from the tockenbucket model i have understood that:

"tokens(each token equal to a byte) are placed in a bucket,if the tokens
in bucket become equal to packetsize then packet leaves the network
element."

(1)Correct me if my understanding of tocken bucket(as given above) is
wrong
(2)Why at all i need a tocken bucket model.What is the use of it.?
(3)who places the tockens in the bucket,is it done by the network
element?
(4)Is the bucket size equal to MTU of that network element?
(5)physically whats a token bucket,to what i can relate it to?

thanks
Swayam

---

From: Karthikeyan Nathillvar <[email-masked]>
Date: Wed, 7 Nov 2001 01:06:27 -0600 (CST)

hi,

> in bucket become equal to packetsize then packet leaves the network
      thats right!!!
> (2)Why at all i need a tocken bucket model.What is the use of it.?

    token bucket is mainly used for shaping the traffic at the edges of
the network.
     Consider a VBR video source which generates fixed number of
packets/second. Each packet will be of different length. So the
bitrate(both average and peak) of the traffic varies within a range.
In QoS networks core network expects traffic to be confined to particular
traffic limits. Using token bucket algorithm, VBR source's traffic can
be shaped at the edges so that it is confined to the traffic expected in core.

> (3)who places the tockens in the bucket,is it done by the network

   it is just an algorithim which is used for traffic shaping.

> (4)Is the bucket size equal to MTU of that network element?

  the bucket size will be the maximum burst a packet can carry.

> (5)physically whats a token bucket,to what i can relate it to?

    for more information, u can go thru the QoS chapter in book Computer
Networks - A Systems Approach by Peterson and Davie.

reg.
karthik