My point being that the response you will see at a workstation will not
always be the same as the response you will see at the console of a Cisco
router. The router generally has a more robust implementation of ICMP then
the Windows workstation. In a sniffer trace you will see certain types of
ICMP replies that the Windows boxes simply report as destination
unreachables, or even timeouts even though the ICMP type as specified by6
the RFC's is not simply unreachable.
Of course, that is what I meant. Not that the workstation sends an ICMP, but
that what it recieves from the router is simply a timeout.
----- Original Message -----
From: "Priscilla Oppenheimer" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, November 20, 2000 4:47 PM
Subject: Re: !H !H !H!H
At 03:25 PM 11/20/00, Chris Larson wrote:
>Even if this was correct you cannot simply by getting an !h say that this
is
>from an access-list. There are many reasons for a host unreachable message.
>
>Also, from most workstations (Windows that is), you will simply get a
>timeout and neither !A or !h from packets being denied by an access-list.
Sending a Destination Unreachable is the job of the Router, not the
workstation. Whether it sends an A, H, or nothing depends on the
implementation of ICMP that it is running.
Priscilla
>----- Original Message -----
>From: "Rossetti, Stan" <[EMAIL PROTECTED]>
>To: "'Jennifer Cribbs'" <[EMAIL PROTECTED]>; "cisco"
><[EMAIL PROTECTED]>; "Rossetti, Stan" <[EMAIL PROTECTED]>
>Sent: Monday, November 20, 2000 2:23 PM
>Subject: RE: !H !H !H!H
>
>
>Are you sure? Page 1163 of Cisco IOS Configuration Fundamentals states
that
>the character A signifies that the destination is "Administratively
>Unreachable. Usually, this output indicates that an access list is
blocking
>traffic."
>
>-----Original Message-----
>From: Jennifer Cribbs [mailto:[EMAIL PROTECTED]]
>Sent: Monday, November 20, 2000 1:13 PM
>To: cisco; [EMAIL PROTECTED]
>Subject: RE: !H !H !H!H
>
>
>On the traceroute command:
>
>!H is returned 3 times if an access list prevents a router from forwarding
>the
>packet to the HOST. The 'trace' command is used to determine the route
>taken
>to a remote host. All the hops are shown as the trace probe moves toward
>the
>destination. Three probes are issued. The response time of each probe
will
>
>be displayed if successful.
>
>The trace command returns a N if the network is unreachable.
>The P is the response if the protocol is unreachable.
>An * is a timeout.
>!H is the return for what I said above but it is regarding a traceroute
>command,
>and not a ping.
>
>Jennifer Cribbs
>[EMAIL PROTECTED]
>
>
>
> >===== Original Message From "Rossetti, Stan"
<[EMAIL PROTECTED]>
>=====
> >I thought !A meant this path is blocked by an access list.
> >
> >-----Original Message-----
> >From: Jennifer Cribbs [mailto:[EMAIL PROTECTED]]
> >Sent: Monday, November 20, 2000 12:13 PM
> >To: [EMAIL PROTECTED]
> >Subject: RE: !H not a complete answer
> >
> >
> >This response is returned when an access list somewhere along the path
> >prevents a router from forwarding a packet to the HOST.
> >
> >and that is correct.
> >
> >Jennifer Cribbs
> >[EMAIL PROTECTED]
> >
> >
> >>===== Original Message From "Croyle, James" <[EMAIL PROTECTED]>
=====
> >>http://www.cisco.com/warp/public/112/chapter7.htm
> >>
> >>I think you have a routing loop as is described here. Ping from several
> >>stations and map it out.
> >>
> >>Jim
> >>
> >>
> >>-----Original Message-----
> >>From: Miller, Nathan (AZ15)
> >>To: Richard Bosire; Jason yee
> >>Cc: John Huston; [EMAIL PROTECTED]
> >>Sent: 11/20/00 11:15 AM
> >>Subject: RE: !H
> >>
> >>Does it meas that the destination NETWORK is unreachable or the
> >>destination
> >>HOST??
> >>
> >>-----Original Message-----
> >>From: Richard Bosire [mailto:[EMAIL PROTECTED]]
> >>Sent: Monday, November 20, 2000 8:01 AM
> >>To: Jason yee
> >>Cc: John Huston; [EMAIL PROTECTED]
> >>Subject: Re: !H
> >>
> >>
> >>destination unreachable i.e not path to the destination network
> >>
> >>Jason yee wrote:
> >>
> >>> hi anyone knows what does the symbol !H means in
> >>> traceroute results
> >>>
> >>> __________________________________________________
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> >>--
> >>_______________________________________________
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> >>
> >>Richard Bosire
> >>Network Engineer CCNA,CCSE
> >>AfricaOnline (k) Ltd
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> >>
> >>
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> >_________________________________
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>
>_________________________________
>FAQ, list archives, and subscription info:
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________________________
Priscilla Oppenheimer
http://www.priscilla.com
_________________________________
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