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How to find out EIGRP Release Version

As some feature on the EIGRP can be limited to the version of EIGRP you are running on the router.

This can be determined by using the command show eigrp plugins

EIGRP Plugin Info
R1#show eigrp plugins 
EIGRP feature plugins:::
    eigrp-release      :  10.00.00 : Portable EIGRP Release                  
                       :   1.00.08 : Source Component Release(rel10)
    parser             :   2.02.00 : EIGRP Parser Support                    
    igrp2              :   2.00.00 : Reliable Transport/Dual Database        
    manet              :   3.00.00 : Mobile ad-hoc network (MANET)           
    bfd                :   2.00.00 : BFD Platform Support                    
    eigrp-pfr          :   1.00.01 : Performance Routing Support             
    EVN/vNets          :   1.00.00 : Easy Virtual Network (EVN/vNets)        
    ipv4-af            :   2.01.01 : Routing Protocol Support                
    ipv4-sf            :   1.02.00 : Service Distribution Support            
    ipv6-af            :   2.01.01 : Routing Protocol Support                
    ipv6-sf            :   2.01.00 : Service Distribution Support            
    vNets-parse        :   1.00.00 : EIGRP vNets Parse Support               
    snmp-agent         :   1.01.01 : SNMP/SNMPv2 Agent Support               

How to remember BGP Selection Process

“We Love Oranges AS Oranges Mean Pure Refreshment”

W – Weight (Highest)
L – LOCAL_PREF (Highest)
O – Originate (local) routes that are advertise through the “network” command or redistributed from an IGP.
AS – AS_PATH (shortest)
O – ORIGIN Code (IGP > EGP > Incomplete)
MMED (lowest)
P – Paths (External > Internal)
RRID (lowest)

Fine-tuning BGP Client / Server Relationship

Before you read through this post, I assume you have got at least the basic understanding of BGP and how it works.

Here are some facts…

BGP is a path vector Routing Protocol works on TCP port 179.

Neighbor with the lowers IP address will establish the connection to the Remote Peer on TCP port 179 with a random source port.

In this case, the Remote Peer will become the Server and the Local Peer will become the client. This peering relationship will change when we clear the BGP process on either peer or the underlying BGP connection get severed for any reason.

In case you want to specifically want to set one Peer as the Server and one as the Client, the IOS does support it.

This is how it is done…

[continue reading…]

BGP Peer Templates

I have came across a lot of BGP configurations where there are lot of the configurations can be optimized. But having said that, this is not always the case when the Network is being built gradually.

Here is a couple of them, called Peer Session Templates and Peer Policy Templates; which we can use in such BGP configuration optimisations, when we…

  1. Design a Network from scratch.
  2. Design with a future overview.

These configurations can be used when it comes to commands which are session specific.

  • description
  • disable-connected-check
  • ebgp-multihop
  • exit peer-session
  • inherit peer-session
  • local-as
  • password
  • remote-as
  • shutdown
  • timers
  • translate-update
  • update-source
  • version

I wouldn’t personally set password on a template, because…

  1. You might want to have a different password for a specific peer because it is controlled by some other Administrative body.
  2. In my opinion, it is best practice to set the password per peer than to have it under a template.

Here is an example configuration from Cisco and also take a look at the Peer Policy Templates which is used under address-family. I would strongly advise you to read through the whole document.

[continue reading…]

OSPF Loopback Interface

OSPF Loopback interfaces are treated as a stub host and will only have a 32 bit host route on the other devices no matter how the subnet mask is entered under the OSPF network statement.

We will explore how we can disable this default behaviour using a few methods.


As you can see, R4 is configured with IP address and R5 with

We have loopback interfaces added with /24 subnet masks on R4 and R5

R4#sh run int loop0
Building configuration...
Current configuration : 61 bytes
interface Loopback0
ip address

R5#sh run int loop 0
Building configuration...
Current configuration : 61 bytes
interface Loopback0
ip address

We are running basic OSPF Configs as follows…

[continue reading…]

Convert IPv4 into IPv6

I was going through 6to4 tunnel configs and thought I’d post some info on converting IPv4 address into IPv6 Address. This is pretty straight forward and its obviously involves HEX conversion.

Method 1 (Please also see Method 2 below as I think it is much more easier)

Here, I will convert the address

First we divide each octet by 16 and write down the remainder, primary school maths! 🙂

192 ÷ 16 = 12 remainder 0
168 ÷ 16 = 10 remainder 8
25 ÷ 16 = 1 remainder 9
234 ÷ 16 = 14 remainder 10

We also know that HEX has the following Values

A = 10
B = 11
C = 12
D = 13
E = 14
F = 15

So we can write into HEX like so… C0A8:19EA

Now we will change the HEX Address C0A8:19EA into regular IPv4

C0 = (12 x 16) + 0 = 192
A8 = (10 x 16) + 8 = 168
19 = (1 x 16) + 9 = 25
EA = (14 x 16) + 10 = 234


Method 2

Another easier way to convert is to convert the octets into Binary, in this case we will still use the IP address

Split those above 32Bit into equal 16 Bits as HEX is based on Base of 16, then Add them up.


IPv6 Link Local Address

Since we have converted the IPv4 address into hexadecimal, this can be written into the following 128-Bit IPv6 link-local address FE80:0000:0000:0000:0000:0000:C0A8:19EA which can be zero compressed into FE80::C0A8:19EA

And finally…

Hope I have explained it thoroughly so you could follow… If you have any doubts, feel free to add your comments.

BGP no-export vs local-as

This is one of the BGP configuration I have came across on my lab…

no-export : This will keep the route inside the confederation, but not to any peers.

local-as : This will keep the route inside the AS, but not even to confederation peers.

no-export –> local-as –> no-advertise

If there is no confederation present, no-export will reflect the same result as local-as.

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