Basic VRRP Configuration

VRRP- Virtual Router Redundancy Protocol

I have written about HSRP in previous post. Today I am going to write on VRRP.
 
There are 3 main benefits to using VRRP over HSRP.
1.Open Standard (We can use any vendor's router)
2.Faster then HSRP
3.No need to give ip of any virtual router.

In VRRP we'll give ip of a router interface. So that router which interface we are going to use for VRRP will become Master.And there is no preemption because by default Master router have maximum priority (255) and Backup have 100. So if someone configure priority 255 of backup it'll not coop to become Master.

Topology--

  Simplest topology ever. 2 router (3600 Series) with a Ether Switch Module installed (NM-16ESW). 1 switch and one cloud in which I have configured loopback(ip-192.168.1.100192.168.1.100 and gateway 192.168.1.1) interface by this I can communicate from my PC.

Configuration-

1.Create vlan-50 on both router and give ip-

2.Now make Fast Ethernet member of VLAN-50--

R1(config)#int ran f 1/0 - 1
R1(config-if - range)#switchport mode access
R1(config-if-range)#switchport access vlan 50

and same on R2


R2(config)#int ran f 1/0 - 1
R2(config-if - range)#switchport mode access
R2(config-if-range)#switchport access vlan 50

3.Now configure VRRP on both Routers---

R1(config)#int vlan 50
R1(config-vlan)#vrrp 1 ip 192.168.1.1

After this command you will get a message-
"*Mar  1 00:01:08.439: %VRRP-6-STATECHANGE: Vl50 Grp 1 state Init -> Master"

It means your router become Master now time to configure R2 as R1-

R2(config)#int vlan 50
R2(config-vlan)#vrrp 1 ip 192.168.1.1

And after this command you will get a message-
"*Mar  1 00:01:06.283: %VRRP-6-STATECHANGE: Vl50 Grp 1 state Master -> Backup "

It means your R2 become Backup.

Testing-

To see vrrp Configuration type

R1#show vrrp

 

And to see configuration on R2  same command

Now try to ping 192.168.1.1 from you pc.

 

It is successful. Now shutdown vlan interface of R1 (On which we have configured 192.168.1.1).

 On R1 you will see a message--

 

And on R2-

 

So now your R2 become Master, now try to ping 192.168.1.1 again from pc--

 

And still you can see that we are able to ping.

 

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EIGRP Neighborhood and Metric

EIGRP Neighborhood and Metric-

Neighborghood-

Metric Calculation -

1.Bandwidth (K1)                -1 By Default
2.Delay (K3)                       - 1 BY Default
3.Reliability (K4 and K5)     - 0 By Default
4.Loading (k2)                     - 0 By default
5.MTU (Maximum Transmission Unit)


Metric-

(K1 * BW +((K2 * BW) / (256- load)) + K3 * Delay ) * (K5/(Reliability + K4 ))

BW= 10^7/ BW
Delay= Delay in Microsecond

Real (Default Metric)-

256 * (Slowest_BW + All_Link_Delay)

EIGRP TABLES AND TERMINOLOGY

EIGRP TABLES AND TERMINOLOGY

A Router running EIGRP maintains three tables-

1. Neighbor Table-
        By sending hello message EIGRP and OSPF create neighbor relationship and keep their information in Neighbor Table. If you talk about RIP then it doesn't create neighbor relationship it just send a multicast message and receive multicast messages of others.

2.Topology Table-
       OSPF contain all possible path in Topology Table but EIGRP contain only Successor and Feasible Successor in Topology Table. 

3.Routing Table-
      Like other routing protocol EIGRP also have Routing Table which contain best path.

Terminology-

   
In this topology I have 3 routers R0, R1 and R2 as you can see. R1 is connected to R0 with 100 Kb link and R0 is connected to R2 with 50 Kb link.I sitting om switch 0 with blink eye.:P

Now EIGRP will choose 100 Lb link as primary.And 50 Kb link as a Backup.

1.Feasible Distance (FD)-
       How far router from you. Lets cost from S0 to R1 and R2 is same that is 500. But Cost from R1 to R0 and R2 to R0 will be different because they both are connected with different speed link.Let cost for R1- R0 link is 1000 so cost for R2-R0 will we 2000.
      So FD for primary link is -500 + 1000 = 1500
     And FD for second link is  -1000 + 1000 = 2000

2.Advertise Distance (AD)-
      How far router is from your neighbor.
      So AD for primary and secondary is same - 1000

3.Successor - Primary link is called successor.

4.Feasible Successor - Backup link is called Feasible.

Note- "To be considered a Feasible Successor AD must be less then FD of successor.
Here AD is 1000 and FD of successor is 1500 so it'll become FS."


Note- " SO if EIGRP doesn't has FS in topology table and in case of link failure it send Query Message to it's neighbor. And if it's neighbor found that path from another neighbor or itself it'll reply with AD and if it doesn't found any path it'll reply with AD with infinity value (router will not choose this one)."

5.Active Router - 
       Router which actively looking for backup.(not a good thing.)

6.Passive Router -
      Router have at least one FS and everything is fine.
      

EIGRP Concept

EIGRP (Enhanced Interior Gateway Routing Protocol)

Today I'm going to talk about best routing protocol.That is EIGRP. It was Cisco Proprietary but in Mid-2013 it become open standard. Even it was very famous before become open standard.

Here are some reasons why I am saying it best-
 
1.Backup Routes-
           EIGRP contain Backup Routes in it's Topology table, so in case of any failure this Backup Route goes up.So what OSPF and IS-IS also have topology table and backup path also so why EIGRP???

          Yes right OSPF and IS-IS also have Topology table like EIGRP. But EIGRP have backup route as Feasible Successor (all pre-calculated paths in case of failure ) so in case of failure Feasible Successor become Successor in few millisecond. In OSPF and IS-IS they contains every possible path in topology table so in case of any failuer OSPF run SPF Algo. to calculate best path and it takes some time.

2.Simple Configuration-
         Configuration of EIGRP are very simple and easy to understand.

3.Flexibility in  Summarization -
         In OSPF there is only specific places like ABR, ASBR where you can summarize route, but in EIGRP you can summarize route at any point of network.

4.Unequal cost Load- Balancing -
        If you have to different bw connection and you want to do Load- balancing between them according to their bandwidth. For eg. I have two connection one is 2MPS and another is 1MBPS. And I want when I send 2 packet over 2 MBPS connection next packet should go on 1 MBPS or can say you want a packet sending ratio 2:1. So with help of EIGRP this is also possible.

5.Combines best of Distance Vector and Link State -
     That's a topic of debate.Book says it is Hybrid. Cisco says it is Advance Distance Vector but I say it simply Distance Vector. And I haven't said that believe me ... :P :D

Internal Components of a Cisco Router

The Internal Components of a Cisco Router

1)Bootstrap --
       Stored in the microcode of the ROM.It will boot the router and then load the IOS.

2)POST(Power On Self Test)--
      Stored in the microcode of the ROM, the POST is used to check the basic functionality of the router hardware and determines which interfaces are present.

3)ROM Monitor --
     Stored in the microcode of the ROM, the ROM monitor is used manufacturing, testing and troubleshooting.

4)Mini-IOS --
     RxBOOT or boot-loader, small IOS in ROM that can be used to bring up an interface and load a Cisco IOS into flash memory.

5)RAM --
    Used to hold packet buffers, ARP cache, routing table and also the software and data structure that allow the router to function.Store  Running-Configuration. Most router expend IOS from flash into RAM at time of boot.

6)ROM --
    Used to store and maintain the routes. Hold the POST and Bootstrap program as well as mini IOS.

7)Flash Memory --
    Store the Cisco IOS by default. Flash memory is not erased when the router is reloaded. It is EEPROM created by Intel.

8)NVRAM --
    Used to hold the router and switch configuration. NVRAM is not erased when the router or switch is reloaded. And NVRAM doesn't store an IOS. The configuration register is stored in NVRAM.

9)Configuration Register --
    Used to control how the router boot up. By default value is 0x2102, which tells the router to load the IOS from Flash Memory as well as load the configuration from NVRAM.