From: wing_lam@jossynergy.com
Date: Tue Jun 24 2003 - 07:19:11 GMT-3
Hi, thx you guys response and hints;
After I disabled the "ip forward-protocol spanning-tree", all the helpered
packets can be seen by "debug ip pac detail". I think it's my mistake that
configure it accidentally.
Now, the question is; why this command will prevent helper address from
working? I hardly understand this command.
Thx a lot,
BBD (Big Black Dog)
"Snow, Tim"
<timothy.snow@eds To: "'Jonathan V Hays'" <jhays@jtan.com>
.com> cc: "'ccielab@groupstudy.com'" <ccielab@groupstudy.com>
Sent by: Subject: RE: helper address
nobody@groupstudy
.com
06/22/2003 03:52
PM
Please respond to
"Snow, Tim"
No but there is a really cool "debug dhcp detail" that will show the client
requests and your router forwarding them on to the remote server and seeing
if the server responds. I use it all the time to point the finger at our
DHCP admins, atleast at that point I can say "see, we're sending the
requests to you, are you getting them, turn on tcpdump" and the typical
response is "uuuuuhhh, yes, I see the request coming in, but the server not
replying, lemme restart the service" and voila!!!
r1#debug dhcp deta
DHCP client activity debugging is on (detailed)
Tim
-----Original Message-----
From: Jonathan V Hays [mailto:jhays@jtan.com]
Sent: Saturday, June 21, 2003 2:07 PM
To: ccielab@groupstudy.com
Cc: wing_lam@jossynergy.com
Subject: RE: helper address
Hi,
You are right that "debug ip packet detail" seems a bit flaky in this
instance.
I spent some time experimenting with "ip helper-address" myself,
generating DHCP Discover messages to be forwarded by the router to a
remote server. Not only did I not see the packets on the remote segment,
"debug ip packet detail" does not always see the DHCP Discover
broadcasts from the client on the LOCAL segment, even when my PC sniffer
sees them. Hmmm. Strange ....
Jonathan
> -----Original Message-----
> From: wing_lam@jossynergy.com [mailto:wing_lam@jossynergy.com]
> Sent: Monday, June 23, 2003 11:15 AM
> To: Jonathan V Hays
> Cc: ccielab@groupstudy.com
> Subject: RE: helper address
>
>
>
> Hi Jonathan,
>
> I am generating UDP broadcast by port 2000 traffic in
> 192.168.1.0/24 subnet
> and I have used helper address and forward-protocol in the router:
>
> Host broadcast --> 192.168.1.1 router -- ATM p-to-p--
> 192.168.2.4 router
>
> My comand is ip helper-address 192.168.2.4 & ip
> forward-protocol udp 2000
>
> But when I "debug ip packet detail" in the 192.168.2.4
> router, I haven't
> see any packet comes.
>
> Should I able to see these helpered packets in 192.168.2.4
> router? or it's
> normal that I cannot see them?
>
> The following is my interface config
>
> interface FastEthernet0/0
> ip address 192.168.1.1 255.255.255.0
> ip helper-address 192.168.2.4
> ip directed-broadcast
> ip router isis DOG
> ip pim dr-priority 100
>
> Thx,
> BBD (Big Black Dog)
>
>
>
>
>
>
> "Jonathan V Hays"
>
>
> <jhays@jtan.com> To:
> <ccielab@groupstudy.com>
>
> cc:
> <wing_lam@jossynergy.com>
>
> 06/21/2003 11:05 Subject: RE:
> helper address
>
> PM
>
>
>
>
>
>
>
>
>
>
>
>
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> > Behalf Of wing_lam@jossynergy.com
> > Sent: Monday, June 23, 2003 5:23 AM
> > To: ccielab@groupstudy.com
> > Subject: helper address
> >
> >
> > Hi, Group;
> >
> > I would like to test the "ip helper" address function. I
> > generate a subnet
> > broadcast in a interface and using helper address to redircet
> > this subnet
> > broadcast to another host, but no matter I do what debugging,
> > I cannot see
> > packet go to the host; anybody please suggest a testing
> > method on whether
> > the helper address config is success.
>
>
> Please be more specific. Given the sketchy information you
> have provided
> we would have to do a LOT of guessing to figure out what you
> are doing.
>
> 1. Post your config.
>
> 2. Describe the topology.
>
> 3. Describe exactly what you are doing to test. How are you generating
> the broadcast? On what machine? Another router? What kind of broadcast
> are you generating? What debug command are you using and where are you
> using it?
>
> Note that the "ip helper-address" forwards specific broadcasts for the
> eight UDP destination ports below:
>
> 37 time server
> 49 TACACS
> 53 DNS
> 67 BOOTP/DHCP Server
> 68 BOOTP/DHCP Client
> 69 TFTP
> 137 NETBIOS Name Service
> 138 NETBIOS Datagram Service
>
> So if you are testing the helper-address command you will have to
> generate one of those types of broadcasts.
>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/
fipras_r/1rfipadr.htm#1018608
HTH
This archive was generated by hypermail 2.1.4 : Fri Jul 04 2003 - 11:11:05 GMT-3