Task 13.7

This task doesnt really work for me, I had to get some help using the SG but it still not works

 

Here is what I got on the DHCP Relay :  DHCP: Server ID Option: 155.1.146.6

 DHCP: offer received from 155.1.146.6

 DHCP: offer received in bad state: Purging  punt

 DHCP: XID did NOT MATCH in dhcpc_for_us()

 DHCP: XID did NOT MATCH in dhcpc_for_us()

 DHCP: XID did NOT MATCH in dhcpc_for_us()

 DHCP: XID did NOT MATCH in dhcpc_for_us()

 DHCP: QScan: Purging entry

 DHCP: deleting entry 85639618 0.0.0.0 from list

 Temp IP addr: 0.0.0.0  for peer on Interface: Serial1/3

 Temp  sub net mask: 0.0.0.0

    DHCP Lease server: 0.0.0.0, state: 9 Purging

    DHCP transaction id: 140F

    Lease: 0 secs,  Renewal: 0 secs,  Rebind: 0 secs

    No timer running

    Retry count: 0   Client-ID: cisco-155.1.23.3-Serial1/3

    Client-ID hex dump: 636973636F2D3135352E312E32332E33

                        2D53657269616C312F33

    Hostname: Rack1R3

 

 

The communication is ok between the DHCP server and the relay but there is an ID mistmatch and I have no ID what this is ... 

 

anybody got the same ?

Comments

  • I did this one today for the 2nd time (I had hope now  I'm a bit stronger than 3 months ago) and still it doesn't work for me. I tried everything from static routes to black magic.

    I have the exact same output as you Nicolas/

    Looks like DHCPOFFER are not taken care by R3. I think this scenario can't work, please advice if I'm wrong.

    I setup a tunnel between R3 and R6 (to rule out any forwarding path issue - network 36.36.36.0/24) and configured 36.36.36.6 as dhcp server at R3. Packets reach R6, DHCP process them and unicasts to R3. However this is what I get debugging at R3:

    Jun 12 08:23:43.509: IP: s=36.36.36.6 (Tunnel36), d=155.14.23.3 (FastEthernet0/0), g=155.14.37.7, len 328, forward
    Jun 12 08:23:43.509:     UDP src=67, dst=67
    Jun 12 08:23:43.693: IP: s=36.36.36.6 (Tunnel36), d=155.14.23.3 (FastEthernet0/0), g=155.14.37.7, len 328, forward
    Jun 12 08:23:43.697:     UDP src=67, dst=67
    Jun 12 08:23:43.881: IP: s=36.36.36.6 (Tunnel36), d=155.14.23.3 (FastEthernet0/0), g=155.14.37.7, len 328, forward
    Jun 12 08:23:43.881:     UDP src=67, dst=67
    Rack14R3#

    since the "dhcp proxy" process uses the IP of the interface it has received dhcp requests to, R6 sends back to  155.14.23.3. R6 has a route matching this network via the tunnel. However, since the protocol is down at R3, because of RIP reflection it tries to forward to SW1 or R4 (depends on what route hears first):

     

    Rack14R3#sh ip route 155.14.23.3
    Routing entry for 155.14.23.0/24
      Known via "rip", distance 120, metric 2
      Redistributing via rip
      Last update from 155.14.37.7 on FastEthernet0/0, 00:00:02 ago
      Routing Descriptor Blocks:
      * 155.14.37.7, from 155.14.37.7, 00:00:02 ago, via FastEthernet0/0
          Route metric is 2, traffic share count is 1

    RSRack13AS>2
    [Resuming connection 2 to R2 ... ]

    Rack14R2(config-if)#shut
    Rack14R2(config-if)#
    RSRack13AS>3
    [Resuming connection 3 to R3 ... ]

    Jun 12 08:29:24.921: %LINK-3-UPDOWN: Interface Serial1/3, changed
    Jun 12 08:30:05.623: %LINK-3-UPDOWN: Interface Serial1/3, changed state to down
    Rack14R3#
    Jun 12 08:30:05.627: is_up: 0 state: 0 sub state: 1 line: 0 has_route: True
    Jun 12 08:30:05.631: RT: interface Serial1/3 removed from routing table
    Jun 12 08:30:05.631: RT: del 155.14.23.0/24 via 0.0.0.0, connected metric [0/0]
    Jun 12 08:30:05.631: RT: delete subnet route to 155.14.23.0/24
    Jun 12 08:30:05.631: RT: NET-RED 155.14.23.0/24
    Jun 12 08:30:06.625: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/3, changed state to down
    Rack14R3#
    Jun 12 08:30:06.625: is_up: 0 state: 0 sub state: 1 line: 0 has_route: False
    Jun 12 08:30:06.925: RT: SET_LAST_RDB for 155.14.23.0/24
      NEW rdb: via 155.14.0.4

    Jun 12 08:30:06.925: RT: add 155.14.23.0/24 via 155.14.0.4, rip metric [120/3]
    Jun 12 08:30:06.925: RT: NET-RED 155.14.23.0/24

    If I configure a local policy route at R3 and trick R6 to see R3 loopback as source of the dhcp relay I think it'll fail because the pool will be allocated using R3 loopback and a pool is not present. Of course I could use the client id and an host pool... well this is just theory I don't even know if it'll work (didn't try).

     

    EDIT: I've just seen this post:

    http://ieoc.com/forums/t/4810.aspx

    I think it'll break the lab rules (renumber an interface) but I guess that if stuff like this happens in the exam they know there's a "legal" way to accomplish the task.

  • just to confirm the ip unnumbered solution works

     

    Cheers

  • Here is another gotcha - at least for 12.4(15)T6.
    The DHCP Proxy Agent (R3) will only accept the DHCP Offer if the server is from the "approved list". So if you configure one IP address for the DHCP server (let say R6 loopback: "ip dhcp-server 150.1.6.6"), and the DHCP server uses a different IP to send a packet back (the IP of the interface closest to the DHCP Proxy), the proxy-agent will discard it. You can check this behavior with "debug dhcp" on R3.
    This is NOT the case with DHCP Relay Agent; the Relay Agent will accept offer sent out of any DHCP Server IP address.

  • Nope ...not working for me either.

    I even tried threathening R3 but getting error as below.

    DHCP: XID did NOT MATCH in dhcpc_for_us()

    DHCP: XID did NOT MATCH in dhcpc_for_us()

    DHCP: XID did NOT MATCH in dhcpc_for_us()

    DHCP: XID did NOT MATCH in dhcpc_for_us()

    DHCP: XID did NOT MATCH in dhcpc_for_us()

     

     

     

    Tox!

  • Hi guys,

    Configuration worked for me, after R2 crashed (for whatever reasons), reloaded, I reconfigured it and I got ip address from R6.

    I disabled ppp encap on R2, re-enabled it and it got ip address from R6.

    I won't paste the config on all routers, as it's from SG.

    The debugs from the routers are :

    R6 :

    Rack4R6#
    Sep  5 01:04:14.835: DHCPD: Sending notification of DISCOVER:
    Sep  5 01:04:14.835:   DHCPD: htype 1 chaddr 0011.20cd.7c40
    Sep  5 01:04:14.835:   DHCPD: remote id 020a00009b04920600000092
    Sep  5 01:04:14.835:   DHCPD: circuit id 00000000
    Sep  5 01:04:14.835: DHCPD: DHCPDISCOVER received from client 0063.6973.636f.2d31.3535.2e34.2e32.332e.332d.5365.7269.616c.312f.33 through relay 155.4.23.3.
    Sep  5 01:04:14.835: DHCPD: Seeing if there is an internally specified pool class:
    Sep  5 01:04:14.835:   DHCPD: htype 1 chaddr 0011.20cd.7c40
    Sep  5 01:04:14.835:   DHCPD: remote id 020a00009b04920600000092
    Sep  5 01:04:14.835:   DHCPD: circuit id 00000000
    Rack4R6#
    Sep  5 01:04:14.835: DHCPD: Allocate an address without class information (155.4.23.0)
    Rack4R6#
    Sep  5 01:04:16.835: DHCPD: Adding binding to radix tree (155.4.23.2)
    Sep  5 01:04:16.835: DHCPD: Adding binding to hash tree
    Sep  5 01:04:16.835: DHCPD: assigned IP address 155.4.23.2 to client 0063.6973.636f.2d31.3535.2e34.2e32.332e.332d.5365.7269.616c.312f.33.
    Sep  5 01:04:16.835: DHCPD: Sending DHCPOFFER to client 0063.6973.636f.2d31.3535.2e34.2e32.332e.332d.5365.7269.616c.312f.33 (155.4.23.2).
    Sep  5 01:04:16.835: DHCPD: unicasting BOOTREPLY for client 0011.20cd.7c40 to relay 155.4.23.3.
    Sep  5 01:04:17.107: DHCPD: DHCPREQUEST received from client 0063.6973.636f.2d31.3535.2e34.2e32.332e.332d.5365.7269.616c.312f.33.
    Rack4R6#
    Sep  5 01:04:17.107: DHCPD: Sending notification of ASSIGNMENT:
    Sep  5 01:04:17.107:  DHCPD: address 155.4.23.2 mask 255.255.255.0
    Sep  5 01:04:17.107:   DHCPD: htype 1 chaddr 0011.20cd.7c40
    Sep  5 01:04:17.107:   DHCPD: lease time remaining (secs) = 86400
    Sep  5 01:04:17.107: DHCPD: No default domain to append - abort update
    Sep  5 01:04:17.107: DHCPD: Sending DHCPACK to client 0063.6973.636f.2d31.3535.2e34.2e32.332e.332d.5365.7269.616c.312f.33 (155.4.23.2).
    Sep  5 01:04:17.107: DHCPD: unicasting BOOTREPLY for client 0011.20cd.7c40 to relay 155.4.23.3.
    Rack4R6#
    Sep  5 01:05:33.379: DHCPD: checking for expired leases.
    Rack4R6#
    Sep  5 01:07:33.379: DHCPD: checking for expired leases.
    Rack4R6#
    Sep  5 01:08:34.999: DHCPD: writing bindings to flash:/dhcp_bindings.
    Sep  5 01:08:34.999: DHCPD: ifs_fd_set_size failed (error 2592).
    Sep  5 01:08:35.003: DHCPD: writing address 155.4.23.2.
    Sep  5 01:08:35.003: DHCPD: writing address 155.4.58.3.
    Sep  5 01:08:35.303: DHCPD: wrote automatic bindings to flash:/dhcp_bindings.

    R3 :

    Rack4R3#
    Sep  5 01:04:14.764: DHCP: proxy allocate request
    Sep  5 01:04:14.764: DHCP: new entry. add to queue, interface Serial1/3
    Sep  5 01:04:14.764: DHCP: SDiscover attempt # 1 for entry:
    Sep  5 01:04:14.764: Temp IP addr: 0.0.0.0  for peer on Interface: Serial1/3
    Sep  5 01:04:14.768: Temp  sub net mask: 0.0.0.0
    Sep  5 01:04:14.768:    DHCP Lease server: 0.0.0.0, state: 1 Selecting
    Sep  5 01:04:14.768:    DHCP transaction id: 1678
    Sep  5 01:04:14.768:    Lease: 0 secs,  Renewal: 0 secs,  Rebind: 0 secs
    Sep  5 01:04:14.768:    Next timer fires after: 00:00:04
    Sep  5 01:04:14.768:    Retry count: 1   Client-ID: cisco-155.4.23.3-Serial1/3
    Sep  5 01:04:14.768:    Client-ID hex dump:
    Rack4R3#636973636F2D3135352E342E32332E33
    Sep  5 01:04:14.772:                        2D53657269616C312F33
    Sep  5 01:04:14.772:    Hostname: Rack4R3
    Sep  5 01:04:14.776: DHCP: SDiscover: sending 292 byte length DHCP packet
    Sep  5 01:04:14.776: DHCP: SDiscover 292 bytes
    Rack4R3#
    Sep  5 01:04:17.024: DHCP: XID MATCH in dhcpc_for_us()
    Sep  5 01:04:17.024: DHCP: Received a BOOTREP pkt
    Sep  5 01:04:17.024: DHCP: Scan: Message type: DHCP Offer
    Sep  5 01:04:17.024: DHCP: Scan: Server ID Option: 155.4.146.6 = 9B049206
    Sep  5 01:04:17.028: DHCP: Scan: Lease Time: 86400
    Sep  5 01:04:17.028: DHCP: Scan: Renewal time: 43200
    Sep  5 01:04:17.028: DHCP: Scan: Rebind time: 75600
    Sep  5 01:04:17.028: DHCP: Scan: Subnet Address Option: 255.255.255.0
    Sep  5 01:04:17.028: DHCP: rcvd pkt source: 155.4.146.6,  destination:  155.4.23.3
    Sep  5 01:04:17.028:    UDP  sport: 43,  dport: 43,  length: 308
    Sep  5 01:04:17.028:    DHCP op: 2, htype: 1, hlen: 6, hops: 0
    Sep  5 01:04:17.028:    DHCP server identifier: 155.4.146.6
    Sep  5 01:04:17.028:         xid: 1678, secs: 0, flags: 0
    Sep  5 01:04:17.032:         client: 0.0.0.0, your: 155.4.23.2
    Sep  5 01:04:17.032:         srvr:   0.0.0.0, gw: 155.4.23.3
    Sep  5 01:04:17.032:         options block length: 60

    Sep  5 01:04:17.032: DHCP Offer Message   Offered Address: 155.4.23.2
    Sep  5 01:04:17.032: DHCP: Lease Seconds: 86400    Renewal secs:  43200    Rebind secs:   75600
    Sep  5 01:04:17.032: DHCP: Server ID Option: 155.4.146.6
    Sep  5 01:04:17.032: DHCP: offer received from 155.4.146.6
    Sep  5 01:04:17.036: DHCP: SRequest attempt # 1 for entry:
    Sep  5 01:04:17.036: Temp IP addr: 155.4.23.2  for peer on Interface: Serial1/3
    Sep  5 01:04:17.036: Temp  sub net mask: 255.255.255.0
    Sep  5 01:04:17.036:    DHCP Lease server: 155.4.146.6, state: 2 Requesting
    Sep  5 01:04:17.036:    DHCP transaction id: 1678
    Sep  5 01:04:17.036:    Lease: 86400 secs,  Renewal: 0 secs,  Rebind: 0 secs
    Sep  5 01:04:17.036:    Next timer fires after: 00:00:03
    Sep  5 01:04:17.036:    Retry count: 1   Client-ID: cisco-155.4.23.3-Serial1/3
    Sep  5 01:04:17.036:    Client-ID hex dump: 636973636F2D3135352E342E32332E33
    Sep  5 01:04:17.040:                        2D53657269616C312F33
    Sep  5 01:04:17.040:    Hostname: Rack4R3
    Sep  5 01:04:17.044: DHCP: SRequest- Server ID option: 155.4.146.6
    Sep  5 01:04:17.044: DHCP: SRequest- Requested IP addr option: 155.4.23.2
    Sep  5 01:04:17.044: DHCP: SRequest placed lease len option: 86400
    Sep  5 01:04:17.044: DHCP: SRequest: 310 bytes
    Sep  5 01:04:17.044: DHCP: SRequest: 310 bytes
    Sep  5 01:04:17.296: DHCP: XID MATCH in dhcpc_for_us()
    Sep  5 01:04:17.296: DHCP: Received a BOOTREP pkt
    Sep  5 01:04:17.296: DHCP: Scan: Message type: DHCP Ack
    Sep  5 01:04:17.300: DHCP: Scan: Server ID Option: 155.4.146.6 = 9B049206
    Sep  5 01:04:17.300: DHCP: Scan: Lease Time: 86400
    Sep  5 01:04:17.300: DHCP: Scan: Renewal time: 43200
    Sep  5 01:04:17.300: DHCP: Scan: Rebind time: 75600
    Sep  5 01:04:17.300: DHCP: Scan: Subnet Address Option: 255.255.255.0
    Sep  5 01:04:17.300: DHCP: rcvd pkt source: 155.4.146.6,  destination:  155.4.23.3
    Sep  5 01:04:17.300:    UDP  sport: 43,  dport: 43,  length: 308
    Sep  5 01:04:17.300:    DHCP op: 2, htype: 1, hlen: 6, hops: 0
    Sep  5 01:04:17.300:    DHCP server identifier: 155.4.146.6
    Sep  5 01:04:17.304:         xid: 1678, secs: 0, flags: 0
    Sep  5 01:04:17.304:         client: 0.0.0.0, your: 155.4.23.2
    Sep  5 01:04:17.304:         srvr:   0.0.0.0, gw: 155.4.23.3
    Sep  5 01:04:17.304:         options block length: 60

    Sep  5 01:04:17.304: DHCP Ack Message
    Sep  5 01:04:17.304: DHCP: Lease Seconds: 86400    Renewal secs:  43200    Rebind secs:   75600
    Sep  5 01:04:17.304: DHCP: Server ID Option: 155.4.146.6
    Sep  5 01:04:17.304: DHCP Proxy Client Pooling: ***Allocated IP address: 155.4.23.2

    R2 :

    Rack4R2(config)#int s 0/1
    Rack4R2(config-if)#no encap ppp
    Rack4R2(config-if)#encap ppp
    *Mar  1 00:13:54.427: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/1, changed state to down
    Rack4R2(config-if)#encap p 
    *Mar  1 00:13:56.431: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/1, changed state to up
    Rack4R2(config-if)#do deb ppp not
    Rack4R2(config-if)#do deb ppp negot
    PPP protocol negotiation debugging is on
    Rack4R2(config-if)#encap ppp
    Rack4R2(config-if)#^Z
    Rack4R2#
    Rack4R2#
    *Mar  1 00:14:12.437: Se0/1 PPP: Phase is DOWN, Setup
    *Mar  1 00:14:12.441: Se0/1 PPP: Using default call direction
    *Mar  1 00:14:12.441: Se0/1 PPP: Treating connection as a dedicated line
    *Mar  1 00:14:12.441: Se0/1 PPP: Session handle[F3000003] Session id[0]
    *Mar  1 00:14:12.441: Se0/1 PPP: Phase is ESTABLISHING, Active Open
    *Mar  1 00:14:12.441: Se0/1 LCP: O CONFREQ [Closed] id 1 len 10
    *Mar  1 00:14:12.441: Se0/1 LCP:    MagicNumber 0x120E223C (0x0506120E223C)
    *Mar  1 00:14:12.445: %SYS-5-CONFIG_I: Configured from console by console
    *Mar  1 00:14:12.453: Se0/1 LCP: I CONFREQ [REQsent] id 28 len 10
    *Mar  1 00:14:12.453: Se0/1 LCP:    MagicNumber 0x11D3CC9A (0x050611D3CC9A)
    *Mar  1 00:14:12.453: Se0/1 LCP: O CONFACK [REQsent] id 28 len 10
    *Mar  1 00:14:12.453: Se0/1 LCP:    MagicNumber 0x11D3CC9A (0x050611D3CC9A)
    *Mar  1 00:14:12.453: Se0/1 LCP: I CONFACK [ACKsent] id 1 len 10
    *Mar  1 00:14:12.457: Se0/1 LCP:    MagicNumber 0x120E223C (0x0506120E223C)
    *Mar  1 00:14:12.457: Se0/1 LCP: State is Open
    *Mar  1 00:14:12.457: Se0/1 PPP: Phase is FORWARDING, Attempting Forward
    *Mar  1 00:14:12.457: Se0/1 PPP: Phase is ESTABLISHING, Finish LCP
    *Mar  1 00:14:12.461: Se0/1 PPP: Phase is UP
    *Mar  1 00:14:12.461: Se0/1 IPCP: O CONFREQ [Closed] id 1 len 10
    *Mar  1 00:14:12.461: Se0/1 IPCP:    Address 0.0.0.0 (0x030600000000)
    *Mar  1 00:14:12.461: Se0/1 CDPCP: O CONFREQ [Closed] id 1 len 4
    *Mar  1 00:14:12.461: Se0/1 PPP: Process pending ncp packets
    *Mar  1 00:14:12.465: Se0/1 IPCP: I CONFREQ [REQsent] id 1 len 10
    *Mar  1 00:14:12.465: Se0/1 IPCP:    Address 155.4.23.3 (0x03069B041703)
    *Mar  1 00:14:12.465: Se0/1 IPCP: O CONFACK [REQsent] id 1 len 10
    *Mar  1 00:14:12.465: Se0/1 IPCP:    Address 155.4.23.3 (0x03069B041703)
    *Mar  1 00:14:12.469: Se0/1 CDPCP: I CONFREQ [REQsent] id 1 len 4
    *Mar  1 00:14:12.469: Se0/1 CDPCP: O CONFACK [REQsent] id 1 len 4
    *Mar  1 00:14:12.481: Se0/1 CDPCP: I CONFACK [ACKsent] id 1 len 4
    *Mar  1 00:14:12.481: Se0/1 CDPCP: State is Open
    Rack4R2#
    *Mar  1 00:14:14.440: Se0/1 IPCP: Timeout: State ACKsent
    *Mar  1 00:14:14.440: Se0/1 IPCP: O CONFREQ [ACKsent] id 2 len 10
    *Mar  1 00:14:14.440: Se0/1 IPCP:    Address 0.0.0.0 (0x030600000000)
    *Mar  1 00:14:14.460: Se0/1 IPCP: I CONFREQ [ACKsent] id 2 len 10
    *Mar  1 00:14:14.464: Se0/1 IPCP:    Address 155.4.23.3 (0x03069B041703)
    *Mar  1 00:14:14.464: Se0/1 IPCP: O CONFACK [ACKsent] id 2 len 10
    *Mar  1 00:14:14.464: Se0/1 IPCP:    Address 155.4.23.3 (0x03069B041703)
    *Mar  1 00:14:15.025: Se0/1 IPCP: I CONFNAK [ACKsent] id 1 len 10
    *Mar  1 00:14:15.025: Se0/1 IPCP:    Address 155.4.23.2 (0x03069B041702)
    *Mar  1 00:14:15.029: Se0/1 IPCP: ID 1 didn't match 2, discarding packet
    Rack4R2#
    *Mar  1 00:14:15.029: Se0/1 IPCP: I CONFNAK [ACKsent] id 2 len 10
    *Mar  1 00:14:15.029: Se0/1 IPCP:    Address 155.4.23.2 (0x03069B041702)
    *Mar  1 00:14:15.029: Se0/1 IPCP: O CONFREQ [ACKsent] id 3 len 10
    *Mar  1 00:14:15.029: Se0/1 IPCP:    Address 155.4.23.2 (0x03069B041702)
    *Mar  1 00:14:15.037: Se0/1 IPCP: I CONFACK [ACKsent] id 3 len 10
    *Mar  1 00:14:15.037: Se0/1 IPCP:    Address 155.4.23.2 (0x03069B041702)
    *Mar  1 00:14:15.037: Se0/1 IPCP: State is Open
    *Mar  1 00:14:15.041: Se0/1 IPCP: Install negotiated IP interface address 155.4.23.2
    Rack4R2#sh ip int brief
    Interface                  IP-Address      OK? Method Status                Protocol
    FastEthernet0/0            192.10.4.2      YES NVRAM  up                    up     
    Serial0/0                  155.4.0.2       YES NVRAM  up                    up     
    Serial0/1                  155.4.23.2      YES IPCP   up                    up     
    Loopback0                  150.4.2.2       YES NVRAM  up                    up     
    Rack4R2#

     

    Hope it helps.

    Ciprian.

  • Thanks Ciprian,

    This worked for me.

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