8 Replies Latest reply: Nov 28, 2012 6:36 PM by lp4nb RSS

    debug eigrp packets! meaning of flags???

    imecs

      Dear FOLKS!

       

       

       

      anyone have an idee what the FLAG in an debug of eigrp stands for?

       

       

       

      *Mar  1 00:25:12.107: EIGRP: Received UPDATE on FastEthernet0/0 nbr 1.1.1.1

       

       

       

      *Mar  1 00:25:12.107:   AS 1, Flags 0x1, Seq 1/1 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/2

       

       

       

      Flags 0xA?

       

      Flags 0x8?

       

       

       

      the coolest would be if i could have an explanation of the whole line!

       

       

       

      What i could have find out myself is that seq 1/1 stand for that the neighbor sending this as seq 1 and the receiver of the packet has already received till know seq1 as well!

       

       

       

      can i have some clarification?

       

      thx

        • 1. Re: debug eigrp packets! meaning of flags???
          lp4nb

          *Mar  1 00:25:12.107: EIGRP: Received UPDATE on FastEthernet0/0nbr 1.1.1.1

           

           

          *Mar  1 00:25:12.107:   AS 1, Flags 0x1, Seq 1/1 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/2

          its an eigrp update with the initial bit set, that says its the first packet of the update,  with 0 numbers of packets in input and output queues waiting for the transmission, and 0 numbers of unreliable and reliable multicast packets waiting for transmission, but 2 reliable unicast packets are waiting to transmitted.

           

          the flag 0x8 means that this is the last update,

           

          the flag 0x2 means CR bit.

           

          this bit is important, when the router send reliable multicast packet and don't receive any ack with in multicast flow timer, it generates a special hello packet

          which includes TLV seq 0003, and CR bit set, this hello includes the IP address of the neighbors that it received the ack from and it wants them to not entertain the next packet with the seq no as mentioned in this hello packet.

          When other routers receive those packets, and when they find their ip address mentioned in that packet in the seq field, they ignore the next packet with the seqno mentioned in the packet, But the routers that don't find themselves in special hello, they enter the CR mode, which means they have to have receive and process the next packet that's coming from the sender of the hello. This is used to make the neighbor ship process smooth and efficient, so that not every router has to wait because of one faulty router.

           

          other bits, 0xA is 0x8 + 0x2

           

          and 0x00 is no bit set.

          • 2. Re: debug eigrp packets! meaning of flags???
            Martin

            here is what Jeff Dole wrote in hios TCP/IP vol 1 book:

            Flags, in the debug messages, indicate the state of the flags in the EIGRP packet header (see the section "EIGRP Packet Header" later in this chapter). 0x0 indicates that no flags are set. 0x1 indicates that the initialization bit is set. This flag is set when the enclosed route entries are the first in a new neighbor relationship. 0x2 indicates that the conditional receive bit is set. This flag is used in the proprietary Reliable Multicasting algorithm:

            • Seq is the Packet Sequence Number/Acknowledged Sequence Number.
            • idbq indicates packets in the input queue/packets in the output queue of the interface.
            • iidbq indicates unreliable multicast packets awaiting transmission/reliable multicast packets awaiting transmission on the interface.
            • peerQ indicates unreliable unicast packets awaiting transmission/reliable unicast packets awaiting transmission on the interface.
            • serno is a pointer to a doubly linked serial number for the route. This is used by an internal (and proprietary) mechanism for tracking the correct route information in a rapidly changing topology.

            source: Dole, J. TCP/IP Vol I, 2nd edition, Cisco Press.

            • 3. Re: debug eigrp packets! meaning of flags???
              imecs

              thx man!

              i try to eat myself trough this! do you maybe recommend any detaild documataion on this,where you learned it from?thx anyway

              • 4. Re: debug eigrp packets! meaning of flags???
                lp4nb

                you might find this helpful, although, the format is irritating at some places, i wrote it last year in a hurry, it might be little confusing too.!

                • 5. Re: debug eigrp packets! meaning of flags???
                  imecs

                  i was reading trough your doc, (tx again) and dont want to get lost in it, so a quick question , before i continue from the first snipet

                   

                  `A sent UPDATE packet, from a neighbor can contain an ACK in it, so it server 2 purposes at the same time, sending an update, and acknowleding as well`, sorry but wanna be on the safe side!

                  ????

                  • 6. Re: debug eigrp packets! meaning of flags???
                    lp4nb

                    no no, its just the inference, as acknowledged seq no is 0. If there were some acknowledgements, this acknowledged seq no wouldn't be zero.

                    • 7. Re: debug eigrp packets! meaning of flags???
                      imecs

                      sorry for bothering you with this! but plaese may i have you clarification on this!

                       

                      1. does every sequence have to be acknowleged, if so have a look at my output and, colud you explain

                       

                      R1

                      Nov 28 23:27:57.081: EIGRP: Sending UPDATE on Serial0/1 nbr 13.13.13.3

                      Nov 28 23:27:57.081:   AS 1, Flags 0x1, Seq 1/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1

                      R2

                      Nov 28 23:27:57.085: EIGRP: Received UPDATE on Serial0/1 nbr 13.13.13.1

                      Nov 28 23:27:57.085:   AS 1, Flags 0x1, Seq 1/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ

                      un/rely 0/1

                       

                      R2

                      Nov 28 23:27:57.085: EIGRP: Sending UPDATE on Serial0/1 nbr 13.13.13.1

                      Nov 28 23:27:57.085:   AS 1, Flags 0x1, Seq 1/1 idbQ 0/0 iidbQ un/rely 0/0 peerQ

                      un/rely 0/1

                       

                      How can R2 send  an update (last highlighted row) with a seq 1/1, if the second 1 in 1/1 is the acknowleged seq in by router R2 but R1 haven`t even send and ACK!

                       

                      Thx for you efford!

                      attached the whole output, as well!

                       

                       

                      R1#

                      Nov 28 23:27:57.069:   %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 13.13.13.3 (Serial0/1) is up: new   adjacency

                      Nov 28 23:27:57.073: EIGRP:   Enqueueing UPDATE on Serial0/1 nbr 13.13.13.3 iidbQ un/rely 0/1 peerQ un/rely   0/0

                      Nov 28 23:27:57.081: EIGRP: Sending UPDATE on   Serial0/1 nbr 13.13.13.3

                      Nov 28 23:27:57.081:     AS 1, Flags 0x1, Seq 1/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1

                      Nov 28 23:27:57.081: EIGRP:   Enqueueing UPDATE on Serial0/1 iidbQ un/rely 0/1 serno 1-1

                      Nov 28 23:27:57.085: EIGRP:   Enqueueing UPDATE on Serial0/1 nbr 13.13.13.3 iidbQ un/rely 0/0 peerQ un/rely   0/1 serno 1-1

                      Nov 28 23:27:57.105: EIGRP: Received UPDATE on Serial0/1 nbr 13.13.13.3

                      Nov 28 23:27:57.105:   AS 1,   Flags 0x1, Seq 1/1 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/2

                      Nov 28 23:27:57.109: EIGRP: Sending UPDATE on   Serial0/1 nbr 13.13.13.3

                      Nov 28 23:27:57.109:     AS 1, Flags 0x8, Seq 2/0 idbQ 0/0 iidbQ un/rely 0/1 peerQ un/rely 0/1   serno 1-1

                      Nov 28 23:27:57.109: EIGRP:   Enqueueing ACK on Serial0/1 nbr

                      R1# 13.13.13.3

                      Nov 28 23:27:57.109:   Ack seq 1 iidbQ un/rely 0/1 peerQ un/rely   1/1

                      Nov 28 23:27:57.113: EIGRP: Sending ACK on Serial0/1   nbr 13.13.13.3

                      Nov 28 23:27:57.113:     AS 1, Flags 0x0, Seq 0/1 idbQ 0/0 iidbQ un/rely 0/1 peerQ un/rely 1/1

                      Nov 28 23:27:57.129: EIGRP:   Received UPDATE on Serial0/1 nbr 13.13.13.3

                      Nov 28 23:27:57.133:   AS 1, Flags 0x8, Seq 2/2 idbQ 0/0 iidbQ   un/rely 0/0 peerQ un/rely 0/2

                      Nov 28 23:27:57.133: EIGRP:   Sending UPDATE on Serial0/1 nbr 13.13.13.3

                      Nov 28 23:27:57.133:   AS 1, Flags 0x8, Seq 3/1 idbQ 0/0 iidbQ un/rely   0/0 peerQ un/rely 0/1 serno 1-1

                      Nov 28 23:27:57.137: EIGRP:   Enqueueing ACK on Serial0/1 nbr 13.13.13.3

                      Nov 28 23:27:57.137:   Ack seq 2 iidbQ un/rely 0/0 peerQ un/rely   1/1

                      Nov 28 23:27:57.137: EIGRP:   Sending ACK on Serial0/1 nbr 13.13.13.3

                      Nov 28 23:27:57.137:   AS 1, Flags 0x0, Seq 0/2 idbQ 0/0 iidbQ   un/rely 0/0 peerQ un/rely 1/1

                      Nov 28 23:27:57.153: EIGRP:   Received ACK on Serial0/1 nbr 13.13.13.3

                      Nov 28 23:27:57.157:   AS 1, Flags 0x0, Seq 0/3 idbQ 0/0 iidbQ   un/rely 0/0 peerQ un/rely 0/1

                      Nov 28 23:27:57.161: EIGRP:   Received UPDATE on Serial0/1 nbr 13.13.13.3

                      Nov 28 23:27:57.161:   AS 1, Flags 0x8, Seq 3/3 idbQ 0/0 iidbQ   un/rely 0/0 peerQ un/rely 0/0

                      Nov 28 23:27:57.161: EIGRP:   Enqueueing ACK on Serial0/1 nbr 13.13.13.3

                      Nov 28 23:27:57.165:   Ack seq 3 iidbQ un/rely 0/0 peerQ un/rely   1/0

                      Nov 28 23:27:57.165: EIGRP:   Sending ACK on Serial0/1 nbr 13.13.13.3

                      Nov 28 23:27:57.165:   AS 1, Flags 0x0, Seq 0/3 idbQ 0/0 iidbQ   un/rely 0/0 peerQ un/rely 1/0

                      R1#

                      R2#

                      Nov 28 23:27:57.077:   %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 13.13.13.1 (Serial0/1) is up: new   adjacency

                      Nov 28 23:27:57.077:   EIGRP: Enqueueing UPDATE on Serial0/1 nbr 13.13.13.1 iidbQun/rely 0/1 peerQ   un/rely 0/0

                      Nov 28 23:27:57.085: EIGRP: Received UPDATE on Serial0/1 nbr 13.13.13.1

                      Nov 28 23:27:57.085:   AS 1,   Flags 0x1, Seq 1/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ

                      un/rely 0/1

                      Nov 28 23:27:57.085: EIGRP: Sending UPDATE on   Serial0/1 nbr 13.13.13.1

                      Nov 28 23:27:57.085:     AS 1, Flags 0x1, Seq 1/1 idbQ 0/0 iidbQ un/rely 0/0 peerQ

                      un/rely 0/1

                      Nov 28 23:27:57.089:   EIGRP: Enqueueing UPDATE on Serial0/1 iidbQ un/rely 0/1 ser

                      no 1-1

                      Nov 28 23:27:57.093:   EIGRP: Enqueueing UPDATE on Serial0/1 nbr 13.13.13.1 iidbQ

                      un/rely 0/0 peerQ un/rely   0/1 serno 1-1

                      Nov 28 23:27:57.109: EIGRP: Received UPDATE on Serial0/1 nbr 13.13.13.1

                      Nov 28 23:27:57.109:   AS 1,   Flags 0x8, Seq 2/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ

                      un/rely 0/2

                      Nov 28 23:27:57.113: EIGRP: Received ACK on Serial0/1 nbr 13.13.13.1

                      Nov 28 23:27:57.113:   AS 1,   Flags 0x0, Seq 0/1 idbQ 0/0 iidbQ un/rely 0/0 peerQ

                      un/rely 0/2

                      Nov 28 23:27:57.117: EIGRP: Sending UPDATE on   Serial0/1 nbr 13.13.13.1

                      Nov 28 23:27:57.117:     AS 1, Flags 0x8, Seq 2/2 idbQ 0/0 iidbQ un/rely 0/1 peerQ

                      un/rely 0/1   serno 1-1

                      Nov 28 23:27:57.133:   EIGRP: Received UPDATE on Serial0/1 nbr 13.13.13.1

                      Nov 28 23:27:57.137:   AS 1, Flags 0x8, Seq 3/1 idbQ 0/0 iidbQ   un/rely 0/0 peerQ

                      un/rely 0/2

                      Nov 28 23:27:57.137:   EIGRP: Enqueueing ACK on Serial0/1 nbr 13.13.13.1

                      Nov 28 23:27:57.137:   Ack seq 3 iidbQ un/rely 0/0 peerQ un/rely   1/2

                      Nov 28 23:27:57.141:   EIGRP: Sending ACK on Serial0/1 nbr 13.13.13.1

                      Nov 28 23:27:57.141:   AS 1, Flags 0x0, Seq 0/3 idbQ 1/0 iidbQ   un/rely 0/0 peerQ

                      un/rely 1/2

                      Nov 28 23:27:57.145:   EIGRP: Received ACK on Serial0/1 nbr 13.13.13.1

                      Nov 28 23:27:57.145:   AS 1, Flags 0x0, Seq 0/2 idbQ 0/0 iidbQ   un/rely 0/0 peerQ

                      un/rely 0/2

                      Nov 28 23:27:57.145:   EIGRP: Sending UPDATE on Serial0/1 nbr 13.13.13.1

                      Nov 28 23:27:57.145:   AS 1, Flags 0x8, Seq 3/3 idbQ 0/0 iidbQ   un/rely 0/0 peerQ

                      un/rely 0/1 serno 1-1

                      Nov 28 23:27:57.165:   EIGRP: Received ACK on Serial0/1 nbr 13.13.13.1

                      Nov 28 23:27:57.165:   AS 1, Flags 0x0, Seq 0/3 idbQ 0/0 iidbQ   un/rely 0/0 peerQ

                      un/rely 0/1

                      • 8. Re: debug eigrp packets! meaning of flags???
                        lp4nb


                        Sorry for all the confusion, the ACKs can be sent as merged within the other unicast packets.

                        So, if you happen to see the seq no increment, that means that the acks are there otherwise there is no increment.

                        You can use "show ip eigrp traffic" command to see the no of acks sent received and match them according to the debug output, and also, you could wireshark.


                        Here, R1 is acknowledging the seq no 1 with a ack packet, however, R2 isn't. The first ACK packet That R2 is sending is

                        for Seq 3. That means 2 ack packets have been merged in other unicast packets. If you'd have collected it into wireshark,

                        you would have found them in unicast packets.



                         

                         

                        R1#

                        Nov 28 23:27:57.069:   %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 13.13.13.3 (Serial0/1) is up: new   adjacency

                        Nov 28 23:27:57.073: EIGRP:   Enqueueing UPDATE on Serial0/1 nbr 13.13.13.3 iidbQ un/rely 0/1 peerQ un/rely   0/0

                        Nov 28 23:27:57.081: EIGRP: Sending UPDATE on   Serial0/1 nbr 13.13.13.3

                        Nov 28 23:27:57.081:     AS 1, Flags 0x1, Seq 1/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1

                        Nov 28 23:27:57.081: EIGRP:   Enqueueing UPDATE on Serial0/1 iidbQ un/rely 0/1 serno 1-1

                        Nov 28 23:27:57.085: EIGRP:   Enqueueing UPDATE on Serial0/1 nbr 13.13.13.3 iidbQ un/rely 0/0 peerQ un/rely   0/1 serno 1-1

                        Nov 28 23:27:57.105: EIGRP: Received UPDATE on Serial0/1 nbr 13.13.13.3

                        Nov 28 23:27:57.105:   AS 1,   Flags 0x1, Seq 1/1 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/2

                        Nov 28 23:27:57.109: EIGRP: Sending UPDATE on   Serial0/1 nbr 13.13.13.3

                        Nov 28 23:27:57.109:     AS 1, Flags 0x8, Seq 2/0 idbQ 0/0 iidbQ un/rely 0/1 peerQ un/rely 0/1   serno 1-1

                        Nov 28 23:27:57.109: EIGRP:   Enqueueing ACK on Serial0/1 nbr

                        R1# 13.13.13.3

                        Nov 28 23:27:57.109:   Ack seq 1 iidbQ un/rely 0/1 peerQ un/rely   1/1

                        Nov 28 23:27:57.113: EIGRP: Sending ACK on Serial0/1   nbr 13.13.13.3

                        Nov 28 23:27:57.113:     AS 1, Flags 0x0, Seq 0/1 idbQ 0/0 iidbQ un/rely 0/1 peerQ un/rely 1/1

                        Nov 28 23:27:57.129: EIGRP:   Received UPDATE on Serial0/1 nbr 13.13.13.3

                        Nov 28 23:27:57.133:   AS 1, Flags 0x8, Seq 2/2 idbQ 0/0 iidbQ   un/rely 0/0 peerQ un/rely 0/2

                        Nov 28 23:27:57.133: EIGRP:   Sending UPDATE on Serial0/1 nbr 13.13.13.3

                        Nov 28 23:27:57.133:   AS 1, Flags 0x8, Seq 3/1 idbQ 0/0 iidbQ un/rely   0/0 peerQ un/rely 0/1 serno 1-1

                        Nov 28 23:27:57.137: EIGRP:   Enqueueing ACK on Serial0/1 nbr 13.13.13.3

                        Nov 28 23:27:57.137:   Ack seq 2 iidbQ un/rely 0/0 peerQ un/rely   1/1

                        Nov 28 23:27:57.137: EIGRP:   Sending ACK on Serial0/1 nbr 13.13.13.3

                        Nov 28 23:27:57.137:   AS 1, Flags 0x0, Seq 0/2 idbQ 0/0 iidbQ   un/rely 0/0 peerQ un/rely 1/1

                        Nov 28 23:27:57.153: EIGRP:   Received ACK on Serial0/1 nbr 13.13.13.3

                        Nov 28 23:27:57.157:   AS 1, Flags 0x0, Seq 0/3 idbQ 0/0 iidbQ   un/rely 0/0 peerQ un/rely 0/1

                        Nov 28 23:27:57.161: EIGRP:   Received UPDATE on Serial0/1 nbr 13.13.13.3

                        Nov 28 23:27:57.161:   AS 1, Flags 0x8, Seq 3/3 idbQ 0/0 iidbQ   un/rely 0/0 peerQ un/rely 0/0

                        Nov 28 23:27:57.161: EIGRP:   Enqueueing ACK on Serial0/1 nbr 13.13.13.3

                        Nov 28 23:27:57.165:   Ack seq 3 iidbQ un/rely 0/0 peerQ un/rely   1/0

                        Nov 28 23:27:57.165: EIGRP:   Sending ACK on Serial0/1 nbr 13.13.13.3

                        Nov 28 23:27:57.165:   AS 1, Flags 0x0, Seq 0/3 idbQ 0/0 iidbQ   un/rely 0/0 peerQ un/rely 1/0

                        R1#

                        R2#

                        Nov 28 23:27:57.077:   %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 13.13.13.1 (Serial0/1) is up: new   adjacency

                        Nov 28 23:27:57.077:   EIGRP: Enqueueing UPDATE on Serial0/1 nbr 13.13.13.1 iidbQun/rely 0/1 peerQ   un/rely 0/0

                        Nov 28 23:27:57.085: EIGRP: Received UPDATE on Serial0/1 nbr 13.13.13.1

                        Nov 28 23:27:57.085:   AS 1,   Flags 0x1, Seq 1/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ

                        un/rely 0/1

                        Nov 28 23:27:57.085: EIGRP: Sending UPDATE on   Serial0/1 nbr 13.13.13.1

                        Nov 28 23:27:57.085:     AS 1, Flags 0x1, Seq 1/1 idbQ 0/0 iidbQ un/rely 0/0 peerQ

                        un/rely 0/1

                        Nov 28 23:27:57.089:   EIGRP: Enqueueing UPDATE on Serial0/1 iidbQ un/rely 0/1 ser

                        no 1-1

                        Nov 28 23:27:57.093:   EIGRP: Enqueueing UPDATE on Serial0/1 nbr 13.13.13.1 iidbQ

                        un/rely 0/0 peerQ un/rely   0/1 serno 1-1

                        Nov 28 23:27:57.109: EIGRP: Received UPDATE on Serial0/1 nbr 13.13.13.1

                        Nov 28 23:27:57.109:   AS 1,   Flags 0x8, Seq 2/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ

                        un/rely 0/2

                        Nov 28 23:27:57.113: EIGRP: Received ACK on Serial0/1 nbr 13.13.13.1

                        Nov 28 23:27:57.113:   AS 1,   Flags 0x0, Seq 0/1 idbQ 0/0 iidbQ un/rely 0/0 peerQ

                        un/rely 0/2

                        Nov 28 23:27:57.117: EIGRP: Sending UPDATE on   Serial0/1 nbr 13.13.13.1

                        Nov 28 23:27:57.117:     AS 1, Flags 0x8, Seq 2/2 idbQ 0/0 iidbQ un/rely 0/1 peerQ

                        un/rely 0/1   serno 1-1

                        Nov 28 23:27:57.133:   EIGRP: Received UPDATE on Serial0/1 nbr 13.13.13.1

                        Nov 28 23:27:57.137:   AS 1, Flags 0x8, Seq 3/1 idbQ 0/0 iidbQ   un/rely 0/0 peerQ

                        un/rely 0/2

                        Nov 28 23:27:57.137:   EIGRP: Enqueueing ACK on Serial0/1 nbr 13.13.13.1

                        Nov 28 23:27:57.137:   Ack seq 3 iidbQ un/rely 0/0 peerQ un/rely   1/2

                        Nov 28 23:27:57.141:   EIGRP: Sending ACK on Serial0/1 nbr 13.13.13.1

                        Nov 28 23:27:57.141:   AS 1, Flags 0x0, Seq 0/3 idbQ 1/0 iidbQ   un/rely 0/0 peerQ

                        un/rely 1/2

                        Nov 28 23:27:57.145:   EIGRP: Received ACK on Serial0/1 nbr 13.13.13.1

                        Nov 28 23:27:57.145:   AS 1, Flags 0x0, Seq 0/2 idbQ 0/0 iidbQ   un/rely 0/0 peerQ

                        un/rely 0/2

                        Nov 28 23:27:57.145:   EIGRP: Sending UPDATE on Serial0/1 nbr 13.13.13.1

                        Nov 28 23:27:57.145:   AS 1, Flags 0x8, Seq 3/3 idbQ 0/0 iidbQ   un/rely 0/0 peerQ

                        un/rely 0/1 serno 1-1

                        Nov 28 23:27:57.165:   EIGRP: Received ACK on Serial0/1 nbr 13.13.13.1

                        Nov 28 23:27:57.165:   AS 1, Flags 0x0, Seq 0/3 idbQ 0/0 iidbQ   un/rely 0/0 peerQ

                        un/rely 0/1