From: Church, Chuck (cchurch@wamnetgov.com)
Date: Sun Feb 22 2004 - 22:16:09 GMT-3
There seems to be a lot of confusion on this subject still. 'IP forward protocol' by itself doesn't do anything. It only modifies the behavior of IP helper addresses used on interfaces. Configuring an IP helper address on an interface without any ip forward protocol commands will change the packets destination address to that configured on the helper address statement if (1) the original destination address was 255.255.255.255 and (2) the destination protocol was one of the 7 (I think) that are forwarded by default. Changing those 7 (using 'ip forward-protocol' and 'no ip forward-protocol' statements) will change that behavior for all interfaces using a helper address statement. It would block netbios shares if broadcasts are the only method of name resolution. Not very effective, versus using access lists.
Chuck Church
Lead Design Engineer
CCIE #8776, MCNE, MCSE
Wam!Net Government Services
13665 Dulles Technology Dr. Ste 250
Herndon, VA 20171
Office: 703-480-2569
Cell: 703-819-3495
cchurch@wamnetgov.com
PGP key: http://pgp.mit.edu:11371/pks/lookup?op=index&search=cchurch%40wamnetgov.com
-----Original Message-----
From: Michael Snyder [mailto:msnyder@revolutioncomputer.com]
Sent: Sunday, February 22, 2004 7:52 PM
To: ccielab@groupstudy.com
Cc: 'Bala Ganesh'
Subject: RE: IP forward protocol
Does that mean I can turn off netbios shares using?
no ip forward-protocol netbios-dgm
no ip forward-protocol netbios-ns
no ip forward-protocol netbios-ss
I know someone who has been doing this with an access-list for years.
-----Original Message-----
From: Bala Ganesh [mailto:ganesh@topguntechnologies.com]
Sent: Sunday, February 22, 2004 3:53 PM
To: Casey, Paul (6822); ccielab@groupstudy.com
Subject: Re: IP forward protocol
Hello,
The scenario which you are asking for needs "ip forward-protocol udp
tftp"
on all the routers.
the helper command can be used if you want all of the default UDP prots
to
be forwarded.
----- Original Message -----
From: "Casey, Paul (6822)" <Paul.Casey@o2.com>
To: <ccielab@groupstudy.com>
Sent: Monday, February 23, 2004 3:06 AM
Subject: RE: IP forward protocol
> Hello,
>
> ok, ,say I have eth0--r1---r2---r3----r4----r5-fa0/0
>
> and I want to forward tftp (Trivial File Transfer Protocol (69) )
across
the
> network from r5-fa0/0 to r1-eth0
> how do I do this..?? and not forward all other protocols/.
>
> When and when not, do i use the helper command, and what configuration
do
> the routers in the middle need.
>
> Any help appreciated.
> Kind regards.
>
>
>
>
>
>
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