EIGRP (Associate to Professional level)

Hi Laz,

In EIGRP introduction tutorial, I think the AD value advertised by R3 to R1 should be 9 instead of 12( how could you say 12 ) and in return AD advertised by R1 to R3( If advertisements possible b/w neighbors it must be FD to reach Destination) is 12 don’t understandable, why R1 advertise (FD or AD=12) to R3 , you has not mentioned anywhere the neighbors will advertise the AD and FD to each other if this is possible then R4 advertise Ad=9 to R3 and in return R3 will advertise same to R4 ?

Hi Rene/Laz,

Query pertaining to eigrp neighbor adjacency topic,

How R2 sending update message before hello message ?, I think first of all they form adjacency by sending and receiving hellos to each other then later will send update messages ?

Hi Laz,

Could you explain what these message showing along with meaning of given fields name like idqq 0/0, iidbQ un/rely 0/0, peerQ un/rely 0/0 etc ?

We’ll see on the console of R1 that it receives an UPDATE message, some ACKS and that’s it…

R1#
EIGRP: Received UPDATE on FastEthernet0/0 nbr 192.168.12.2
 AS 12, Flags 0x0, Seq 22/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
EIGRP: Enqueueing ACK on FastEthernet0/0 nbr 192.168.12.2
  Ack seq 22 iidbQ un/rely 0/0 peerQ un/rely 1/0
EIGRP: Sending ACK on FastEthernet0/0 nbr 192.168.12.2
  AS 12, Flags 0x0, Seq 0/22 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 1/0
EIGRP: Enqueueing UPDATE on FastEthernet0/0 iidbQ un/rely 0/1 serno 3-3
EIGRP: Enqueueing UPDATE on FastEthernet0/0 nbr 192.168.12.2 iidbQ un/rely 0/0 peerQ un/rely 0/0 serno 3-3

Hi Rene/Laz,

When we use concept of variance then in this case FD of FS less than FD of S then according to this FS should be successor and like this concept of load balancing doesn’t set fit b/c now this is a successor and this will be in routing table?

Hi Rene/Laz,

Query related to EIGRP Variance Command Example?

Post using variance will successor be successor or the one which will have lower FD post variance like Feasible successor ?

According to topology you using and command output sh ip route 5.5.5.5 , we can see update received in order like 192.168.14.4, 192.168.13.3 and then successor ?

 192.168.14.4, from 192.168.14.4, 00:00:19 ago, via Serial2/0
      Route metric is 2300416, traffic share count is 17
      Total delay is 25100 microseconds, minimum bandwidth is 1544 Kbit
      Reliability 255/255, minimum MTU 1500 bytes
      Loading 1/255, Hops 2
    192.168.13.3, from 192.168.13.3, 00:00:19 ago, via Ethernet1/0
      Route metric is 412160, traffic share count is 92
      Total delay is 6100 microseconds, minimum bandwidth is 10000 Kbit
      Reliability 255/255, minimum MTU 1500 bytes
      Loading 1/255, Hops 2

A post was merged into an existing topic: Introduction to EIGRP

Hello @pradyumnayadavgla,

This is a typo indeed, I just fixed this in the post.

EIGRP will always start with the neighbor adjacency so the first packets that are exchanged are hello packets. In that lesson, I only showed the UPDATE messages from R2 instead of the entire debug because it wasn’t relevant.

That’s a good question…just looking at the acronyms, it’s not easy to tell. I tried to look it up in the master index which covers debug eigrp packets.

They don’t explain it there. I also looked at an EIGRP packet to see if it matches any of the items you find in a packet. This shows the AS number, flags, and sequence number but that’s pretty much it.

It does show up in the following command:

R1#show eigrp tech-support detailed
EIGRP feature plugins:::
    eigrp-release      :  23.00.00 : Portable EIGRP Release                  
                       :   2.00.15 : Source Component Release(rel23)
                                     + HMAC-SHA-256 Authentication
    parser             :   2.02.00 : EIGRP Parser Support                    
    igrp2              :   2.00.00 : Reliable Transport/Dual Database        
                                     + Wide Metrics
    manet              :   3.00.00 : Mobile ad-hoc network (MANET)           
                                     + IPv4 support
                                     + IPv6 support
    bfd                :   2.00.00 : BFD Platform Support                    
    eigrp-pfr          :   1.00.01 : Performance Routing Support             
                                     + IPv4 PFR
    EVN/vNets          :   1.00.00 : Easy Virtual Network (EVN/vNets)        
                                     + IPv4 EVN/vNets
    ipv4-af            :   2.01.01 : Routing Protocol Support                
                                     + Dynamic Remote Neighbors
    ipv4-sf            :   1.02.00 : Service Distribution Support            
                                     + Dynamic Remote Neighbors
    ipv6-af            :   2.01.01 : Routing Protocol Support                
                                     + Dynamic Remote Neighbors
                                     + IPv6 VRF
    ipv6-sf            :   2.01.00 : Service Distribution Support            
                                     + Dynamic Remote Neighbors
                                     + IPv6 VRF
    vNets-parse        :   1.00.00 : EIGRP vNets Parse Support               
    snmp-agent         :   2.00.00 : SNMP/SNMPv2 Agent Support               
EIGRP Internal Process States
  
 procinfoQ:
   1: 0xFB72680 vrid:1 afi:1 as:1     tableid:0 vrfid:0 tid:0 name:
       topo_ddbQ(1) 0xFB82278 tableid:0 name:base  
       topo_ddbQ.count: 1
   procinfoQ.count: 1
 
     deadQ:
 
      ddbQ:
       1: 0xFB82278 name:base  
      ddbQ.count: 1
 ---------------------------------------------------------

EIGRP Memory Usage:
 
  EIGRP Memory                 In-use Asked-For/Allocated Count  Size  Cfg/Max
  ----------------------------------------------------------------------------
  EIGRP IP pdb            :      8308      8308/8360          1  8308   --/--  
  EIGRP-Core: DDB         :      2508      2508/2560          1  2508   --/--  
  EIGRP-Core: DNDB        :      1340      1340/1600          5   268   --/--  
  EIGRP-Core: DRDB        :      1276      1276/1536          5   255   --/--  
  EIGRP-Core: Dual Events :     30004     30004/30056         1 30004   --/--  
  EIGRP-Core: Dual SIA Ev :     30004     30004/30056         1 30004   --/--  
  EIGRP-Core: Handle Arra :       156       156/312           3    52   --/--  
  EIGRP-Core: IIDB        :      4660      4660/4920          5   932   --/--  
  EIGRP-Core: IIDB Scratc :       132       132/184           1   132   --/--  
  EIGRP-Core: Peer Handle :        80        80/184           2    40   --/--  
  EIGRP-Core: Peer Sub-To :        56        56/160           2    28   --/--  
  EIGRP-Core: Topology II :       516       516/776           5   103   --/--  
  EIGRP-Core: peer        :       348       348/400           1   348   --/--  
  EIGRP-IPv4              :       340       340/392           1   340   --/--  
  EIGRP-IPv4: Netlist     :       112       112/320           4    28   --/--  
  EIGRP-IPv4: Proto Priva :        28        28/80            1    28   --/--  
  EIGRP-IPv4: Protocol In :      3532      3532/3584          1  3532   --/--  
  EIGRP-IPv4: iidb_sb_lis :       112       112/320           4    28   --/--  
  EIGRP-OS: Interface Lin :       112       112/320           4    28   --/--  
  EIGRP-OS: Interface sub :       184       184/392           4    46   --/--  
  EIGRP-Parser: dBase Hdr :      1916      1916/2280          7   273   --/--  
  EIGRP-v4: Work Entry    :        --      4260/4912         --    60   50/0   
  EIGRP: Anchor entries   :        --      7416/10224        --    12  500/0   
  EIGRP: Dummy thread ent :        --        32/168          --    32  200/0   
  EIGRP: ExtData          :        --        24/168          --    24   50/0   
  EIGRP: IOS Socket       :       284       284/336           1   284   --/--  
  EIGRP: Input packet hea :        --      2304/3224         --    16  100/0   
  EIGRP: Large packet buf :        --     57596/65760        --  8228  100/0   
  EIGRP: List Large       :        --      1036/1496         --   148    5/0   
  EIGRP: List Medium      :        --        72/168          --    72   10/0   
  EIGRP: Max packet buffe :        --     16420/168          -- 16420    5/0   
  EIGRP: Medium packet bu :        --       548/168          --   548  100/0   
  EIGRP: Packet descripto :        --      4256/4896         --    56   50/0   
  EIGRP: Queue elements   :        --      8892/10224        --    36  200/0   
  EIGRP: Small Pool       :       112       512/976           7    16   32/0   
  EIGRP: Small packet buf :        --      4444/5224         --    44  100/0   
  EIGRP: Socket           :        28        28/80            1    28   --/--  
  EIGRP: cmd handles      :        64        64/168           2    32   --/--  
  EIGRP: mgd_timer        :      6296      6296/9832         68    92   --/--  
  Total                   :     92508    200208/206984      138    --   --/--  

  Total allocated: 0.197 Mb, 202 Kb, 206984 bytes
---------------------------------------------------------
 
EIGRP-IPv4 Protocol for AS(1)
 {vrid:1 afi:1 as:1 mode:1 tableid:0 vrfid:0 tid:0 name: }
  
          PIDs: Hello: 370  PDM: 369
     Router-ID: 11.11.11.11
       Threads: procinfo: 0xFB6A4D8   ddb: 0xFB6A6E8
         workQ:
         iidbQ: Gi0/0 Gi0/1 Lo0 Lo1
                count: 4
 passive_iidbQ:
         peerQ: 192.168.12.2-(Gi0/1)
                count: 1
 unicast_peerQ:
      suspendQ:
      networkQ: 192.168.12.0
                0.0.0.0
                count: 2
 RedistStructs: src:(0)default  distflag:0x8  ipdb->pdb->mask:0x8
                count: 1
      summaryQ:
  Socket Queue: 0/10000/2/0 (current/max/highest/drops)
   Input Queue: 0/10000/2/0 (current/max/highest/drops)
       GRS/NSF: enabled    hold-timer: 240
  Active Timer: 3 min
      Distance: internal 90 external 170
      Max Path: 4
  Max Hopcount: 100
      Variance: 1
     Rib-scale: 1
    Metric Ver: 32bit
 -------------------------------------------------------------------

These seem to be some internal EIGRP things but they don’t explain it anywhere. In the output above, you also see some references to things like “ddbQ” under the Internal process states.

Keep in mind that variance doesn’t influence the S and FS selection. First we use select the S and FS(es), afterward we can use the variance command to insert FS(es) into the routing table.

Thanks for clearing doubts Rene.

There is one more question Rene,

can there be two successor in a topology if this is possible then can be make one FS among them ?

Hi Rene,

  1. first query is why K1,K3 equals to 1 and K2,K4&K5 equals to 0?, any reason ?

  2. In metric formula we use delay value in tens of microseconds or microseconds ?

Hi Rene/Laz,

Query related to EIGRP Summarization ::

  1. why are we getting different out while using summary-address and summary metric command for summarization ?
    R2#show ip route eigrp
    172.16.0.0/23 is subnetted, 1 subnets
    D 172.16.0.0 [90/30720] via 192.168.12.1, 00:00:53, FastEthernet0/0

R2#show ip route eigrp
172.16.0.0/24 is subnetted, 2 subnets
D 172.16.0.0 [90/2562816] via 192.168.12.1, 00:02:28, FastEthernet0/0
D 172.16.1.0 [90/2562816] via 192.168.12.1, 00:02:28, FastEthernet0/0

I think in both output there must be 172.16.0.0/23 subnetted, 1 subnets … and let’s suppose 172.16.0.0 subnetted in subnets in 2nd output but it should display 172.16.0.0/23 instead of 172.16.0.0/24 ?

  1. Could you fully explain concept of null 0 using topology and for which network ( from which router) ?

Hi Rene/Laz,

Query related to Eigrp default network route ::

In second method we are using 192.168.23.0 as a default n/w as a given topology means if we want to go only this n/w we can go from 192.168.12.2 as per R1 perspective not like default route which states that if we want to go any n/w with any mask follow given next hop ?

Hello Pradyumna

If there are two routes to a particular destination and their cost is equal, you will have two successors, and both routes will be placed in the routing table. Equal cost load balancing will take place between those two routes. In order to make one of the two a FS, you must adjust the cost by adjusting one of the K values to make one route preferable. Take a look at this lesson for more information:

This is the default behaviour of EIGRP and it is based on rigorous testing to find the best parameters that work for most topologies.

The unit is “tens of microseconds”. So a value of 40 is 400 microseconds. More info can be found at this lesson:

This one may be an error in the output. I will let Rene know and get back to you…

You can find out about the Null0 exit interface at the following lesson:


Here’s another example of how it is used in BGP:

The ip default-network command essentially tells the router to route all traffic that doesn’t match any other routing table entry, as if it was destined for 192.168.23.0. In other words, a packet with a destination address of 123.123.123.5 (which is not in the routing table) will be routed as if it was an address in the 192.168.23.0/24 network.

I hope this has been helpful!

Laz

Thanks a lot Laz, I know sometimes you take time to revert back but after all you or Rene team give responses, Your response making me trust on NL and drive me to use Network Lessons more and more.