From: Michael Zuo (mzuo@ixiacom.com)
Date: Tue Nov 28 2006 - 19:02:42 ART
Thanks for the help
Yes, the problem was caused by the DHCP server not knowing the route to
the PPP peer that gives out the address. However, the solution is not
straight forward as mentioned in the previous GS discussion and it has a
little twist to it when I tried it out.
The issues is that when either PPP peer interface restarts (this is very
possible, if proctor restart the router or the router crashes on its
own), the R1 loses connectivity to R5's PPP interface (which gives out
the address). Sometimes elapses before R1 regains the connectivity
(after R5's RIP adds the interface and redistribute it into OSPF and
then to R1's OSPF). During this time the negotiation between PPP peer
will fail because the DHCP did not go thru. And from the debug output,
PPP peers do not keep trying DHCP again (I am by far not a PPP expert,
maybe someone else can shed some light?). at this point, the PPP peers
are stuck, even the interfaces are up, R4 still does not get a IP for
its PPP interface.
I tried a few things and the thing worked best seemed to be adding
policy routing (static routing also works, but probably not allowed in
the real lab) on R1 so that R1 always knows where to forward the DHCP
response even when R5's PPP interface is down.
Anyone else has the same experience?
thanks
-----Original Message-----
From: Deji Steve-Fagbemi [mailto:deji500@hotmail.com]
Sent: Tuesday, November 28, 2006 2:07 AM
To: 'Leon van Dongen'; Michael Zuo
Cc: ccielab@groupstudy.com
Subject: RE: PPP DHCP not working for me, need HELP! (IEWB vol 1, lab
18, task 3.1)
HI,
You need to use the default-router 1.2.3.4 command in the dhcp pool.
(1.2.3.4 is the serial IP address of the router connecting to R4).
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Leon
van Dongen
Sent: 28 November 2006 09:15
To: Michael Zuo
Cc: ccielab@groupstudy.com
Subject: Re: PPP DHCP not working for me, need HELP! (IEWB vol 1, lab
18,
task 3.1)
Hi Michael,
When I read your post I remembered a similar question from some time
ago.
It comes down to the reachability of the gateway address <giaddr>.
http://www.groupstudy.com/archives/ccielab/200607/msg00449.html
HTH
--Leon
>
> van: "Michael Zuo" <mzuo@ixiacom.com>
> datum: 2006/11/28 Tue AM 09:52:47 MET
> aan: "Cisco certification" <ccielab@groupstudy.com>
> onderwerp: PPP DHCP not working for me, need HELP! (IEWB vol 1, lab
18,
> task 3.1)
>
> Hi group,
>
>
>
> I ran into a problem with using DHCP for PPP links. My R4 is supposed
> to get DHCP IP thru PPP peer R5, R1 is the DHCP server. I get (sorry
> about the lengthy paste, which is already abbreviated):
>
>
>
>
>
> R1#
>
> 1d06h: DHCPD: DHCPDISCOVER received from client
> 0063.6973.636f.2d31.3339.2e31.2e
>
> 34.352e.352d.5365.7269.616c.302f.31 through relay 139.1.45.5.
>
> 1d06h: DHCPD: Sending DHCPOFFER to client
> 0063.6973.636f.2d31.3339.2e31.2e34.352
>
> e.352d.5365.7269.616c.302f.31 (139.1.45.4).
>
> 1d06h: DHCPD: unicasting BOOTREPLY for client 00d0.5858.dc40 to relay
> 139.1.45.5
>
> .
>
>
>
> R4(config-if)#
>
> 1d06h: Se0/1 IPCP: TIMEout: State ACKsent
>
> 1d06h: Se0/1 IPCP: O CONFREQ [ACKsent] id 3 len 10
>
> 1d06h: Se0/1 IPCP: Address 0.0.0.0 (0x030600000000)
>
> 1d06h: Se0/1 IPCP: I CONFREQ [ACKsent] id 3 len 10
>
> 1d06h: Se0/1 IPCP: Address 139.1.45.5 (0x03068B012D05)
>
> 1d06h: Se0/1 IPCP: O CONFACK [ACKsent] id 3 len 10
>
> 1d06h: Se0/1 IPCP: Address 139.1.45.5 (0x03068B012D05)
>
> 1d06h: Se0/1 IPCP: I CONFREJ [ACKsent] id 1 len 10
>
> 1d06h: Se0/1 IPCP: Address 0.0.0.0 (0x030600000000)
>
> 1d06h: Se0/1 IPCP: ID 1 didn't match 3, discarding packet
>
> R4(config-if)#
>
> 1d06h: Se0/1 IPCP: TIMEout: State ACKsent
>
> 1d06h: Se0/1 IPCP: O CONFREQ [ACKsent] id 4 len 10
>
> 1d06h: Se0/1 IPCP: Address 0.0.0.0 (0x030600000000)
>
> 1d06h: Se0/1 IPCP: I CONFREQ [ACKsent] id 4 len 10
>
> 1d06h: Se0/1 IPCP: Address 139.1.45.5 (0x03068B012D05)
>
> 1d06h: Se0/1 IPCP: O CONFACK [ACKsent] id 4 len 10
>
> 1d06h: Se0/1 IPCP: Address 139.1.45.5 (0x03068B012D05)
>
> R4(config-if)#
>
>
>
>
>
> 1d06h: DHCP: zapping entry in DHC_PURGING state for Se0/1
>
> 1d06h: DHCP: new entry. add to queue
>
> 1d06h: DHCP: SDiscover attempt # 1 for entry:
>
> 1d06h: DHCP: SDiscover: sending 286 byte length DHCP packet
>
> 1d06h: DHCP: SDiscover 286 bytes
>
> R5(config-if)#
>
> 1d06h: Se0/1 IPCP: TIMEout: State REQsent
>
> 1d06h: Se0/1 IPCP: O CONFREQ [REQsent] id 10 len 10
>
> 1d06h: Se0/1 IPCP: Address 139.1.45.5 (0x03068B012D05)
>
> R5(config-if)#
>
> 1d06h: DHCP: SDiscover attempt # 2 for entry:
>
> 1d06h: DHCP: SDiscover: sending 286 byte length DHCP packet
>
> 1d06h: DHCP: SDiscover 286 bytes
>
> 1d06h: Se0/1 IPCP: TIMEout: State REQsent
>
> 1d06h: Se0/1 IPCP: State is REQsent
>
> 1d06h: Se0/1 IPCP: Cannot satisfy pool request
>
> 1d06h: Se0/1 IPCP: Neither side knows remote address
>
> 1d06h: Se0/1 IPCP: O CONFREJ [REQsent] id 9 len 10
>
> 1d06h: Se0/1 IPCP: Address 0.0.0.0 (0x030600000000)
>
> 1d06h: Se0/1 IPCP: I CONFACK [REQsent] id 8 len 10
>
> 1d06h: Se0/1 IPCP: Address 139.1.45.5 (0x03068B012D05)
>
> 1d06h: Se0/1 IPCP: ID 8 didn't match 10, discarding packet
>
> 1d06h: Se0/1 IPCP: I CONFACK [REQsent] id 9 len 10
>
> 1d06h: Se0/1 IPCP: Address 139.1.45.5 (0x03068B012D05)
>
> 1d06h: Se0/1 IPCP: ID 9 didn't match 10, discarding packet
>
> 1d06h: Se0/1 IPCP: I CONFREQ [REQsent] id 10 len 10
>
> 1d06h: Se0/1 IPCP: Address 0.0.0.0 (0x030600000000)
>
>
>
>
>
> It seems that the DHCP server is responding properly. My
configurations
> are:
>
>
>
> R1:
>
>
>
> ip dhcp excluded-address 139.1.45.1 139.1.45.3
>
> ip dhcp excluded-address 139.1.45.5 139.1.45.255
>
> !
>
> ip dhcp pool P
>
> network 139.1.45.0 255.255.255.0
>
> !
>
>
>
> R4:
>
>
>
> R4(config-if)#do sh run int s0/1
>
> Building configuration...
>
>
>
> Current configuration : 89 bytes
>
> !
>
> interface Serial0/1
>
> ip address negotiated
>
> ip rip advertise 3
>
> encapsulation ppp
>
> end
>
>
>
> R4(config-if)#
>
>
>
>
>
>
>
> R5:
>
>
>
> R5(config-if)#do sh run int s0/1
>
> Building configuration...
>
>
>
> Current configuration : 151 bytes
>
> !
>
> interface Serial0/1
>
> ip address 139.1.45.5 255.255.255.0
>
> ip rip advertise 3
>
> encapsulation ppp
>
> peer default ip address dhcp
>
> clock rate 64000
>
> end
>
>
>
> R5(config-if)#do sh run | in dhcp
>
> ip dhcp-server 139.1.15.1
>
> peer default ip address dhcp
>
> R5(config-if)#do ping 139.1.15.1
>
>
>
> Type escape sequence to abort.
>
> Sending 5, 100-byte ICMP Echos to 139.1.15.1, timeout is 2 seconds:
>
> !!!!!
>
> Success rate is 100 percent (5/5), round-trip min/avg/max = 32/32/32
ms
>
> R5(config-if)#
>
>
>
>
>
> This is pretty much identical to the standard solution to the lab, but
> it is NOT working!! am I missing something simple?
>
>
>
>
>
> Please help!!
>
>
>
>
>
> thanks
>
>
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