Rip loop prevention methods 5(hold down timer)

Holddown is a loop-prevention mechanism employed by distance vector routing protocol. This feature prevents a router from learning new information about a failed route. When a router receives an information about an unreachable route, a holddown timer is started. The router ignores all routing updates for that route until the timer expires (by default, 180 seconds in RIP). Only updates allowed during that period are updates sent from the router that originally advertised the route. If that router advertise the update, the holddown timer is stopped and the routing information is processed.

Rip loop prevention methods 4(Route poisoning)

Route poisoning

Route poisoning is another method for preventing routing loops employed by distance vector routing protocols. When a router detects that one of its directly connected routes has failed, it sends the advertisment for that route with an infinite metric ("poisoning the route"). A router that receives the update knows that the route has failed and doesn't use it anymore.

Rip loop prevention methods 3(poison reverse)

Poison Reverse
When a router receives a route poisoning, it sends an update back to the
router from which it received the route poisoning,

Rip loop prevention methods 2(Triggered updates)

Triggered updates
Well since we are discussing distance vector routing protocols, all routers will eventually converge, but updates are sent out every 30 seconds with a full routing table when things are operating normally. In the case of a failed interface the neighboring router would immediately send out and update, but it would only send out a poison route with a metric of 16. The router would also temporarily suspend split horizon and send out this poisoned route back in the direction it received an update. this would be called split horizon with poison reverse. As soon as the route is considered dead, the hold down timer starts and the routers will not believe any more information about the poisoned route until the hold expires.

Rip loop prevention methods 1(split horizon)

Split Horizon
Distance vector protocols are susceptible to routing loops. Split horizon is one of the features of distance vector routing protocols that prevents them. This feature prevents a router from advertising a route back onto the interface from which it was learned.

layer 3 switch 2(RIP on switch)

layer 3 switch 1(ip address on switch)

VPN 3 (Virtual private network)

VPN 2 (Virtual private network)

VPN 1 (Virtual private network)

ospf basic 2

ospf Router id

Dynamic nat configuration

Types of nat

Nat basic

Extended access list

Standard ACL(host Blocking)

In this example i m trying to block 30.0.0.1 host from my network which is HCL(10.0.0.0)

HCL(config)#ip access-list standard hcl
HCL(config-std-nacl)#deny host 30.0.0.1
HCL(config-std-nacl)#permit any
HCL(config)#interface fastEthernet 0/0
HCL(config-if)#ip access-group hcl out

........................OR................................

HCL(config)#ip access-list standard 10
HCL(config-std-nacl)#deny host 30.0.0.1
HCL(config-std-nacl)#permit any
HCL(config-std-nacl)#exit
HCL(config)#interface fastEthernet 0/0
HCL(config-if)#ip access-group 10 out

........................OR................................

HCL(config)#access-list 10 deny host 30.0.0.1
HCL(config)#access-list 10 permit any
HCL(config)#interface fastEthernet 0/0
HCL(config-if)#ip access-group 10 out

Standard ACL

In this example i m trying  to block 30.0.0.0 network for my network which is HCL(10.0.0.0)

HCL(config)#ip access-list standard HCL
HCL(config-std-nacl)#deny 30.0.0.0 0.255.255.255
HCL(config-std-nacl)#permit any
HCL(config-std-nacl)#exit
HCL(config)#interface fastEthernet 0/0
HCL(config-if)#ip access-group HCL out

........................OR................................
HCL(config)#ip access-list standard 10
HCL(config-std-nacl)#deny 30.0.0.0 0.255.255.255
HCL(config-std-nacl)#permit any
HCL(config-std-nacl)#exit
HCL(config)#interface fastEthernet 0/0
HCL(config-if)#ip access-group 10 out

........................OR................................

HCL(config)#access-list 10 deny 30.0.0.0 0.255.255.255
HCL(config)#access-list 10 permit any
HCL(config)#interface fastEthernet 0/0
HCL(config-if)#ip access-group 10 out

link for internet download manager

http://www.4shared.com/rar/zXdoliRR/internet_download_manager_idm_.htm?locale=en

Extended ACL (network to Host blocking)

Extended ACL for network to Host blocking

HCL(config)#ip access-list extended hcl
HCL(config-ext-nacl)#deny icmp 30.0.0.0 0.255.255.255 host 10.0.0.1
HCL(config-ext-nacl)#permit ip any any
HCL(config-ext-nacl)#inter fa 0/0
HCL(config-if)#ip access-group hcl out
........................................OR.................................................

HCL(config)#ip access-list extended 110
HCL(config-ext-nacl)#deny icmp 30.0.0.0 0.255.255.255 host 10.0.0.1
HCL(config-ext-nacl)#permit ip any any
HCL(config-ext-nacl)#inter fa 0/0
HCL(config-if)#ip access-group 110 out
........................................OR.................................................

HCL(config)#access-list 110 deny icmp 30.0.0.0 0.255.255.255 host 10.0.0.1
HCL(config)#access-list 110 permit ip any any
HCL(config)#inter fa 0/0
HCL(config-if)#ip access-group 110 out

Extended ACL (Host to Host blocking)

Extended ACL for Host to Host blocking

HCL(config)#ip access-list extended hcl
HCL(config-ext-nacl)#deny icmp host 30.0.0.1 host 10.0.0.1
HCL(config-ext-nacl)#permit ip any any
HCL(config-ext-nacl)#inter fa 0/0
HCL(config-if)#ip access-group hcl out
........................................OR.................................................

HCL(config)#ip access-list extended 110
HCL(config-ext-nacl)#deny icmp host 30.0.0.1 host 10.0.0.1
HCL(config-ext-nacl)#permit ip any any
HCL(config-ext-nacl)#inter fa 0/0
HCL(config-if)#ip access-group 110 out
........................................OR.................................................

HCL(config)#access-list 110 deny icmp host 30.0.0.1 host 10.0.0.1
HCL(config)#access-list 110 permit ip any any
HCL(config)#inter fa 0/0
HCL(config-if)#ip access-group 110 out

Extended ACL (Host to Network blocking)

Extended ACL for Host to Network blocking

HCL(config)#ip access-list extended hcl
HCL(config-ext-nacl)#deny icmp host 30.0.0.1 10.0.0.0 0.255.255.255
HCL(config-ext-nacl)#permit ip any any
HCL(config-ext-nacl)#inter fa 0/0
HCL(config-if)#ip access-group hcl out
.......................................OR...........................................

HCL(config)#ip access-list extended 110
HCL(config-ext-nacl)#deny icmp host 30.0.0.1 10.0.0.0 0.255.255.255
HCL(config-ext-nacl)#permit ip any any
HCL(config-ext-nacl)#inter fa 0/0
HCL(config-if)#ip access-group 110 out
.......................................OR...........................................

HCL(config)#access-list 110 deny icmp host 30.0.0.1 10.0.0.0 0.255.255.255
HCL(config)#access-list 110 permit ip any any
HCL(config)#inter fa 0/0
HCL(config-if)#ip access-group 110 out

Extended Access list(network to network blocking)

Extended Access list(network to network blocking)
HCL(config)#ip access-list extended hcl
HCL(config-ext-nacl)#deny icmp 30.0.0.0 0.255.255.255 10.0.0.0 0.255.255.255
HCL(config-ext-nacl)#permit ip any any
HCL(config-ext-nacl)#inter fa 0/0
HCL(config-if)#ip access-group hcl out
..........................................OR............................................

HCL(config)#ip access-list extended 110
HCL(config-ext-nacl)#deny icmp 30.0.0.0 0.255.255.255 10.0.0.0 0.255.255.255
HCL(config-ext-nacl)#permit ip any any
HCL(config-ext-nacl)#inter fa 0/0
HCL(config-if)#ip access-group 110 out
..........................................OR............................................

HCL(config)#access-list 110 deny icmp 30.0.0.0 0.255.255.255 10.0.0.0 0.255.255.255
HCL(config)#access-list 110 permit ip any any
HCL(config)#inter fa 0/0
HCL(config-if)#ip access-group 110 out

static routing with subnetting

Standard Access control list commands

Standard Access control list

IBM(config)#ip access-list standard hcl
IBM(config-std-nacl)#deny 30.0.0.0 0.255.255.255
IBM(config-std-nacl)#permit any
IBM(config)#inter fastEthernet 0/0
IBM(config-if)#ip access-group hcl out
.....................OR...........................
IBM(config)#ip access-list standard 10
IBM(config-std-nacl)#deny 30.0.0.0 0.255.255.255
IBM(config-std-nacl)#permit any
IBM(config)#inter fastEthernet 0/0
IBM(config-if)#ip access-group 10 out
.....................OR...........................
IBM(config)#access-list 10 deny 30.0.0.0 0.255.255.25
IBM(config)#access-list 10 permit any
IBM(config)#inter fastEthernet 0/0
IBM(config-if)#ip access-group 10 out



Block a host through standard ACL

hcl(config)#ip access-list standard hcl
hcl(config-std-nacl)#deny host 30.0.0.1
hcl(config-std-nacl)#permit any
hcl(config)#inter fastEthernet 0/0
hcl(config-if)#ip access-group hcl out
.....................OR...........................
hcl(config)#ip access-list standard 10
hcl(config-std-nacl)#deny host 30.0.0.1 
hcl(config-std-nacl)#permit any
hcl(config)#inter fastEthernet 0/0
hcl(config-if)#ip access-group 10 out
.....................OR...........................
hcl(config)#ACcess-list 10 deny host 30.0.0.1
hcl(config)#access-list 10 permit any
hcl(config)#inter fastEthernet 0/0
hcl(config-if)#ip access-group 10 out

standard ACL cisco

ACL list for host

RIP routing table basics

Like for GNS3

click for GNS3

Link for router ios

Administrative distance of rip

logicsoftwareindia

http://logicsoftwareindia.com/currentopenings.aspx

jobs opportunities in CHD

http://www.tasolutions.in/hr/?page_id=10

cisco discovery protocol

Link for job in Span infotech mohali jobs

Link for job in Span infotech mohali jobs

Address: Industrial Area Mohali, Sector 75, Sahibzada Ajit Singh Nagar, Punjab 140308

redistribute rip to ospf

Download link packet tracer 6.0

If you want to download the Cisco packet tracer than you can download from this link

Packet tarcer 6.0

RIP topology in GNS3

GNS TO computer connection

Support for Windows XP ends next month

Support for Windows XP ends next month, but Microsoft is still delivering "critical" and "important" patches for it. If you're still rocking this aging OS, be sure to download them because they are the last ones you will get.

OSPF configuration

basic intro of OSPF

download TFTP server

GNS basic

Enable telnet in windows 7

VTY

Loopback interface

Rip timers

rip concepts and configuration

static routing

RIP practical

Ip configuration on routers

windows tricks

Intervlan NAT ACL

Switch 1 config


Building configuration...

Current configuration : 1654 bytes
!
version 12.2
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname Switch
!
!
spanning-tree mode pvst
!
interface FastEthernet0/1
 switchport access vlan 10
!
interface FastEthernet0/2
 switchport access vlan 10
!
interface FastEthernet0/3
 switchport access vlan 10
!
interface FastEthernet0/4
 switchport access vlan 10
!
interface FastEthernet0/5
 switchport access vlan 10
!
interface FastEthernet0/6
 switchport access vlan 10
!
interface FastEthernet0/7
 switchport access vlan 10
!
interface FastEthernet0/8
 switchport access vlan 10
!
interface FastEthernet0/9
 switchport access vlan 10
!
interface FastEthernet0/10
 switchport access vlan 10
!
interface FastEthernet0/11
 switchport access vlan 10
!
interface FastEthernet0/12
 switchport access vlan 10
!
interface FastEthernet0/13
 switchport access vlan 10
!
interface FastEthernet0/14
 switchport access vlan 10
!
interface FastEthernet0/15
 switchport access vlan 10
!
interface FastEthernet0/16
 switchport access vlan 10
!
interface FastEthernet0/17
 switchport access vlan 10
!
interface FastEthernet0/18
 switchport access vlan 10
!
interface FastEthernet0/19
 switchport access vlan 10
!
interface FastEthernet0/20
 switchport access vlan 10
!
interface FastEthernet0/21
 switchport access vlan 10
!
interface FastEthernet0/22
 switchport access vlan 10
!
interface FastEthernet0/23
 switchport access vlan 10
!
interface FastEthernet0/24
!
interface GigabitEthernet1/1
!
interface GigabitEthernet1/2
!
interface Vlan1
 no ip address
 shutdown
!
!
line con 0
!
line vty 0 4
 login
line vty 5 15
 login
!
!
end

switch  2