I met a CCIE 3 years ago who confirmed that he
understood that ICMP was used for Ping request/reply
??? but nothing else.
Scarrrrrrrrrrry.
PS: I'm not tarring all CCIE's with the same brush.
But exams are exams at the end of the day.
Phil.
--- Chuck Larrieu <[EMAIL PROTECTED]> wrote: >
-----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]] On Behalf Of
> Priscilla Oppenheimer
> Sent: Monday, August 21, 2000 10:35 AM
> To: Derek CHUNG; [EMAIL PROTECTED]
> Subject: Re: Is a TCP packet encapsulated by a IP
> packet which is inside a
> Layer 2 frame?
>
> <<snip>>
>
> Now Chuck said that nobody could rattle off header
> contents off the top of
> their head. I'm going to see if I can. &;-)
>
> CL: I believe I asked ( rhetorically ) how many
> could do what you did so
> well without referring to a chart or some other
> source. I think even Howard
> admitted he cannot do so at present? ( even if he
> was able to at one time )
>
> IP
> Version
> Header Length
> Type of Service -- precedence, etc.
> Length of Packet
> ID -- all fragments have the same ID
> Flags -- don't fragment, more fragments
> Fragment Offset -- indicates the position of this
> data relative to the
> beginning of a fragmented message
> Time to Live -- decremented by each router until it
> reaches 0, in which
> case the packet is trashed
> Protocol -- next layer up, for example, UDP, TCP,
> EIGRP, OSPF, ICMP, etc.
> Header checksum
> Source IP Address
> Destination IP Address
> Options -- record route, source routing, etc.
> Padding if necessary -- must end on a 32-bit
> boundary
>
> CL: agrees with the source I am checking this
> against
>
> TCP
> Source Port
> Destination Port
> Sequence Number -- each BYTE is sequenced. This
> field specifies the seq #
> of the first byte in this message
> ACK Number
> Header Length
> Flags - Urgent, ACK, PUSH, RESET, SYN, FIN
> Window Size
> Checksum - checksum of header and data
> Urgent Pointer -- points to any urgent data in the
> message
> Options
>
> CL: WOW!!!
>
> Whew! Did it! &;-)
>
> CL: yes you did, PO, and therefore you are entitled
> to ask the rest of us
> how we ever got such and such a certification
> without knowing this ;->
> Still wondering how many CCIE's are unable to
> duplicate your feat. :->
>
> Priscilla
>
>
>
> At 03:59 AM 8/20/00, Derek CHUNG wrote:
> >Is a TCP packet (layer 4) encapsulated by a IP
> packet (layer 3) which is
> >inside a Layer 2 frame?
> >If so, why the headers of a IP packet and TCP
> packet look so similar and
> >redundant?
> >
> CL: I also believe that this premise remains untrue.
> While both IP and TCP
> headers are normally 20 bytes, I see very little
> else in common, as
> befitting the very different functions they perform.
> TCP has more
> reliability functions built in - acknowledgement,
> windowing, etc. whereas IP
> is more oriented towards best effort delivery across
> an internet.
> >___________________________________
> <<snip>>
>
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