LinuxSA Mailing list archives

  From: Andrew Galdes <galdes1@iprimus.com.au>
  To  : <linuxsa@linuxsa.org.au>
  Date: Tue, 9 Jan 2001 00:14:50 +1030

Re: ping

sorry its late.. am tired but..

TCP is on the transport layer and ICMP is too. but surly TCP is needed  to
send a ping.  are you sure that ICMP is on the transport layer?

andrew galdes

`

On Monday 08 January 2001 21:57, you wrote:
> At 10:27 PM 1/8/01 +1030, Andrew Galdes wrote:
> >i dont understand how it can go on TCP and not hit a port...
>
> I never said it was a TCP protocol. I said it is a transport layer
> protocol. The following layers are knowin in the DODRM:
>
>
> +------------------------------------------+
>
> | Application Layer, like Telnet, SMTP ... |
>
> +------------------------------------------+
>
> | Transport Layer, eg TCP, UDP, ICMP ...   |
>
> +------------------------------------------+
>
> | Network Layer, ie IP                     |
>
> +------------------------------------------+
>
> | Link layer, eg Ethernet II, etc ...      |
>
> +------------------------------------------+
>
> The Internet Message Control Protocol (ICMP) is an odd beast.
>
> It is true that it performs functions that logically place it at the
> network layer, such as ICMP Destination Unreachable, however, other
> messages, such as ICMP Echo Request and  ICMP Echo Reply do not belong at
> the network layer!
>
> On the other hand, ICMP messages are carried in IP datagrams, so ICMP is a
> transport layer protocol.
>
> >On Monday 08 January 2001 19:24, you wrote:
> >> At 07:03 PM 1/8/01 +1030, Alex Garner wrote:
> >> >> >  > this is so simple but i just dont know...  when you ping a
> >> >> >  > system, which port (if any) is it hitting?
> >> >> >
> >> >> > It isn't.  It's using ICMP, which doesn't entertain the concept of
> >> >> > "ports".
> >> >>
> >> >> my understanding is that ICMP is on the same level as TCP and UDP.
> >> >
> >> >As far as I was aware, ICMP was considered network layer (layer 3) and
> >> >UDP and TCP are transport layer (layer 4)?
> >>
> >> Whatever ICMP is considered to be, it is carried in IP datagrams, as is
> >> IGMP, and a bunch of other protocols.
> >>
> >> That makes ICMP a transport layer protocol.
> >>
> >> >Cheers
> >> >
> >> >Alex!
> >> >
> >> >
> >> >--
> >> >
> >> >Alex Garner <alex@netcraft.com.au>
> >> >
> >> >NetCraft Australia
> >> >Phone (08) 8338 0888
> >> >http://www.netcraft.com.au
> >> >
> >> >"Don't tell me your problems!" - David Bennett, 1997
> >> >
> >> >--
> >> >LinuxSA WWW: http://www.linuxsa.org.au/  IRC: #linuxsa on
> >> > irc.linux.org.au To unsubscribe from the LinuxSA list:
> >> >  mail linuxsa-request@linuxsa.org.au with "unsubscribe" as the subject
> >>
> >> Regards
> >> -------
> >> Richard Sharpe, sharpe@ns.aus.com
> >> Samba (Team member, www.samba.org), Ethereal (Team member, www.zing.org)
> >> Contributing author, SAMS Teach Yourself Samba in 24 Hours
> >> Author, Special Edition, Using Samba
>
> Regards
> -------
> Richard Sharpe, sharpe@ns.aus.com
> Samba (Team member, www.samba.org), Ethereal (Team member, www.zing.org)
> Contributing author, SAMS Teach Yourself Samba in 24 Hours
> Author, Special Edition, Using Samba

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