VLANS

VLAN types 

Normal Range:- 2-1001 ( configurable )
                        1002 - FDDI
                        1003 - Token Ring ( IBM )
                        1004 - FDDI.net
                        1005 - Trnet           
                        1006 - 1023 - Testing                
Extended Range:- 1024-4095    Uses only in L3 Switch   .
Default all ports in VLAN1.   

Vlan configuration two ways :

1.Traditional Method ( Not recommended )

sw#vlan database
sw# vlan 10
sw# apply
This method will directly write to flash.

Default all ports are in Vlan 1.

name of Vlan file in flash  - vlan.dat

To delete Vlan from flash -> delete flash:vlan.dat

If you removed the running config of the router , then VLAN wont be removed
Vlan saves in FLASH , running config saved in NVRAM.

2.New Method

sw(config)      #vlan 10
sw(config-vlan)#name CCNP 

sw#sh vlan brief   Verification command

Multiple Vlan creation using single command

sw(config)# vlan 2-1001

sw(config)#vlan 2,3,4,5,6-10,13-19

port assigning to vlan 
sw(config)#int fa0/1
sw(config-if)#switchport access vlan 2

Multiple interfaces assigning to Vlan

sw(config)#int range fa0/1-24 ( this command does not work in some of the L3 switches , you have to use space after fa 0/1 - 24 )
sw(config-if-range)#switchport access vlan 3

SWITCHING

In switching use MAC Address ( Media Access Control ) - IANA Internet Assigned Numbers Authority ( will assign MAC)
- L2 Address ( Physical or Hardware address )

MAC Address will represents in 48 bit. It shows in  HEXA decimal , then it comes to 12 digits.
24 bits -OUI (Organizational Unique Identifier ) assigning from IANA plus 24 bits Vendor identifier ( Vendor side assign )

Cisco has lot of mac address , One of the Cisco MAC address starts with 

00000C

HEXA Decimal - 0-9
                       A-F(10-15) Base16
 A- 1010-10
 B- 1011-11
 C- 1100-12
 D- 1101-13
 E- 1110-14
 F- 1111-15

 converting bin --> digit
1010 - 8*1 + 4*0 + 2*1 + 1*0 = 10
1011 - 8*1 + 4*0 + 2*1 + 1*1 = 11

Main difference between router and switch is,switch  doesn't have a power button.

Available mac address 2^48.

Main Switch Functions :-

1.Address Learning
2.Forwarding
3.Loop Avoidance

Address Learning

Keeps all the learned mac address in CAM (Content Addressable Memory).

sw#show mac address table

 By default it switch will show 

port mac method vlan
-      -     cpu       -
-      -     cpu       -

Method will show the in built switch mac addresses.

ARP will use to get the MAC address . 

B-SOFT RACK : CCNP 




Cisco Terminal Sever -2511 

ACCESS SERVER(config)#ip host sw1 2013
ACCESS SERVER#sh line

ACCESS SERVER#sh word

L2 switches : 

2900 
1900

L3 switches :

3500
3700
4000
6000
12000

Hub 

Its a L1 device 

Not Manageable ( No console access )

Single Broadcast and collision Domain

Half duplex

What ever bits comes it broadcast to all

Switch

L2 device

MAC address

Half duplex

Single broadcast domain
Total no. of ports equal to collision domain ( Multiple Collision domain )
Intelligent devices ( console access )


 

PORT NUMBERS

21 FTP
22 SSH
23 TELNET
25 SMTP
53 DNS
67 DHCP
110 POP3
443 SSL ( HTTPS)
161/162 SNMP
3389 RDP
9  IGRP
88 EIGRP
89 OSPF
179 BGP
520 RIP

IP SUBNETTING

/24 - 2>8 - 255.255.255.0       
/25 - 2>7 - 255.255.255.128
/26 - 2>6 - 255.255.255.192
/27 - 2>5 -255.255.255.224
/28 - 2>4 - 255.255.255.240
/29 - 2>3 - 255.255.255.248
/30 - 2>2 - 255.255.255.252
/31 -2>1- 255.255.255.254


Class A - 0 - 126 -- 10.0.0.0 - 10.255.255.255
Class B - 128 -191 -- 172.16.0.0 - 172.31.255.255
Class C - 192 - 223 -- 192.168.0.0 - 192.168.255.255
Class D - 224 - 239 224.0.0.0 -  Mulicast
Class E - 240 -254 research 


1.)

192.168.10.0/27 

255.255.255.224

How many networks - 224/(2^5) = 7

Network address 192.168.10.0
Broadcast address 192.168.10.31
Hosts 192.168.10.1 - 192.168.10.30
How many hosts per network - 30 (32-2)

192.168.10.0
192.168.10.32
192.168.10.64
192.168.10.96
192.168.10.128
192.168.10.160
192.168.10.192
192.168.10.224

2.)


192.168.10.0/28

255.255.255.240

How many networks - 240/ ( 2^4) = 15

Network address 192.168.10.0
Broadcast adddress 192.168.10.15
Hosts 192.168.10.1 - 192.168.10.14
How many hosts per network - 14 (16-2)

192.168.10.0
192.168.10.16
192.168.10.32
192.168.10.48
192.168.10.64
192.168.10.80
192.168.10.96
192.168.10.112
192.168.10.128
192.168.10.144
192.168.10.160
192.168.10.176
192.168.10.192
192.168.10.208
192.168.10.224
192.168.10.240

CCIE

CCIE number starts from 1025.

INTERVIEW QUESTIONS

TCS 

17/3/2012

Primary Skill :-
Network Engineer(4+ yrs)
Network, LAN, WAN, Routing, Switching,Troubleshooting,Cisco Experience

Ques.

1. BGP - Command to check routes advertised
2. Load sharing
3. what is Sup engine , purpose of using sup engine 
4. Scenario : 10 Valns are there required , traffic should load balanced through ROUTER A and ROUTER B. What are steps needs to take.

 5. VTP - If new switch wants to add in  VTP, what and all required to be care of 










XL HEALTH

Experience                          : 3+yrs

·         Install, configure, and maintain network services, equipment and devices.
·         Supports administration of servers and server clusters.
·         Manages all system back-up and restore protocol.
·         Plans and supports network and computing infrastructure.
·         Perform troubleshooting analysis of servers, workstations and associated systems.
·         Documents network problems and resolution for future reference.
·         Monitors system performance and implements performance tuning.
·         Manage user accounts, permissions, email, anti-virus, anti-spam.
·         Requires a thorough knowledge of networking essentials.
·         Oversee software and network security.
·         Strong analytical abilities and professional office experience needed.

Technical Skills:
·         Certifications: MCSE, CCNA
·         Systems: Windows, Cisco Systems,
·         Networking Switches, Routers, Hubs, Servers, Cables, Racks, Firewalls, LAN,WAN,TCP/IP,DNS,UDP, Latency, Volp

Ques.


1.Explain exchange 2003 to 2007 Migration






TECH MAHINDRA

18/3/2012

      Skills required are really fairly standard Cisco skills to CCNP level, but significant hands on experience would be a significant advantage. It’s basically a Branch network of some 100 or so sites, but of course they are all 3rd party sites. The main features used in the Extranet include:
·         IP Clear/MPLS connectivity
·         Some legacy Cellstream/Framestream
·         BGP, RIP and EIGRP routing protocols
·         Extensive use of GRE tunnels.
·         Extensive use of PBR
·         Some IPSEC
·         Some ISDN/ADSL
·         Hardware is mainly 2600, 2800, 3700 and 3800 routers plus 7200 and ASR1004s at the core.

    LAN skills are needed as there is a small LAN environment that BT manage. This is a L2 environment and not that complex, though knowledge of VLAN pruning would be desirable.
 Experience is BGP is must.
 CCNP is mandatory.

Ques.

1. VTP
If new switch has to add in VTP -- Then what and all required on config.
http://jklogic.net/adding-a-cisco-switch-to-a-vtp-domain/
http://ciscotips.wordpress.com/2006/05/23/connecting-a-new-switch/
2. BGP attributes
3. STP process
4. BPDU gurad
5. EIGRP STUCK IN ACTIVE




CSS

24/03/2012

Primary Skill:

* Good understanding of OSI Model, TCP/IP protocol suite (IP, ARP, ICMP, TCP, UDP, SNMP, FTP, TFTP)

And

* Strong knowledge in any of the following skill set

1. Windows or Linux or Citrix (ADS, DNS, DHCP)
2. VPN, Firewall, Checkpoint, Pix
3. RSA, PKI, Digital Certificate
4. IPSEC protocol suite, SSL based VPN, AAA


CTS
31/03/12
Q.
 1. SVI ( Switch Virtual Interface )
 2. IP Sec all states

SWITCHING

Layer 3 routing performed by microprocessor type engines. Which required CPU cycles to examine each packets network header.

In switching frames are forwarded using special hardware called application specific integrated circuits(ASIC).

Routing : Cisco express forwarding (CEF) a database of routes to every destination on the network. It will distributes the packets to ASICs. 

Each switch port has its own collision domain and do not send collisions to any other port.

VLAN routing required L3 device (router or l3 switch).

Network Traffic Model :-

80/20 Rule - 80% of the organization traffic will be in switching .
                   20% will be in routing.

Hierarchical network design :-  

Access Layer 
Distribution Layer
Core Layer

VLAN ( Virtual Local Area Network)

VLAN - IEEE 802.1q 

 

STP ( Spanning Tree Protocol)

IEEE 802.1D - STP

Rapid STP - IEEE 802.1w

First to elect root bridge
  Slowest priority will be the root bridge.Bridges have same priority then smallest mac address will be the root bridge.

STP will temporally blocks the redundant paths.

PVST+ (Per Vlan Spanning Tree) - Each vlan will elect a root switch. Each vlan have its own instance.


To elect the root bridge flood the BPDU (Bridge protocol data unit) and this contains Bridge id and sender id.



After electing root bridge.


Root port - Best path to reach root birdge/switch.
Designated port - Best path to the switched segment.
Alternate port- Backup for the root port.
Backup port - Backup of the Designated port

Port states of STP .

1. Blocking state - All the ports are in this while switch initialization , will listen to the network.
2.Listening state - Will listen the traffic, port is set to forward the frame. Default time of the state is 15secs.
3.Learning state - Will listen the traffic and begin to learn the addresses from connected devices on a segment.
4.Forwarding state - Will forward the traffic as well as continue to learn the addresses from the segment.

Default priority port is - 32768

BGP ( Boarder Gateway Protocol )

AS - Sharing similar routing policies and in single administrative domain.
AS number -  1 - 65535 ( 2 Byte) 
There is  4 byte AS number .
Reserved  64512 - 65535 for  private use.


Single Homed  - Only one exit point to outside.(only one ISP )


BGP message types


1.Open
2.Keeplive
3.Update
4.Notification


Path Attributes 


1. Well known mandatory 
   1.Origin
   2.AS_Path
   3.Next_Hop
2. Well known optional 
   1.Local_preference
   2. Atomic_aggregate
   3.Aggregator
3. Optional transitive
   1.Community
4. Optional non-transitive
   1.Muliti_exit_disc
   2.Originator_id (CISCO)
   3.Cluster list (CISCO)

OSPF

Open Shortest Path First (RFC : 2328 )


OSPF States :

1. Down  : No hello packets received , send the hello packet with its own router id.
2. Init : Hello received without routers id.
3.Two way 
4.Ex-start
5.Exchange
6.Loading
7.Full adjacency

OSPF Packet types :


 1.Hello
 2.Database description (DBD)
 3.Link state request (LSR)
 4.Link state update (LSU)
 5.Link state acknowledgement (LSAck)


Used Dijkstra algorithm to calculate shortest path


Link - Interface on the OSPF router

Link State :- IP address / mask of the interface (Link)
                   Metric (cost) of the link
                   Routers connected to that link
                   Type of the network connected to.

Link state database - All the link states will be keep in LSD.

OSPF Steps

• Flooding link state information
• Making a topological table 
• Shortest path first , using Dijkstra Algorithm. This will rearrange the topology.
• From that shortest path tree will make .Router itself as the root.
• Using these information will create routing table.

LSA - Types 

1.Router link entry - Router . In area only
2.Network link entry - DR
3 & 4. Summary link entry - ABR 
5. Autonomous system external link entry - ASBR


Hello packets will multicast to the address 224.0.0.5. 


OSPF Area Types :

• Backbone area
• Standard area
• Stub area
• Totally stubby area
• Not so stubby area (NSSA)

Link 1
Link 2

OSPF network types:

•  Point to point 
•  Broadcast 
• Non Broadcast
• Non Broadcast multi access 
• Point to multi point 

LINK 1

EIGRP (ENHANCED INTERIOR GATEWAY ROUTING PROTOCOL)

EIGRP is the Cisco proprietary protocol 

Metric = Bandwidth + delay  (32 bit for the metric )

Bandwidth = (10000000/bandwidth) * 256

Delay = ( delay /10 ) * 256

Metrics are follows :- 
1.Bandwidth
2.Delay
3.Reliability
4.Load

Its is a classless routing protocol . Hop count is 255 (default is 100).

Routing table metric = Slowest bandwidth + sum of all delays 

Bandwidth :- 
T1 = 1554K
FE = 10000K
E = 10000K

Delay :-
T1 =20000mS
FE =100mS
E = 1000mS

In EIGRP outside routes (from distributed routes ) are tagged as external routes.
Automatic redistribution between EIGRP and IGRP if its both are same AS.

Metric = K1 * bandwidth + (K2 * bandwidth) / (256 -Load) + (k3 * delay ) + (k5/( reliability * k4)


 
Q. What is the Metric ( cost ) for 192.168.72.0/24 from ROUTER B.

Cost = slowest bandwidth + sum of delays.

= 1,657,856 +
      512,000 +
          2560 
___________
    2172416  

If you look at the routing table you will able to see




EIGRP will do the unequal cost load balancing .

EIGRP TABLES
1.Neighbor  Table :- Keeps all adjacent routers (neighbors) . Protocol wise separate table is there . 
ROUTER# show ip eigrp neighbors

2.Topology Table :- Keeps all the learned routes .Protocol wise separate table is there .(from distribution )
ROUTER# show ip eigrp topology

3.Routing Table :- Keeps the best routes from topology table to all destination.
ROUTER# show ip route


Successor : Easiest route to one destination. Keep in routing table. One or more successor may have to one destination.

Feasible Successor : Backup route for the successor. Keep in topology table.May have one or more FS to same destination.


Key Technologies of EIGRP :

Neighbor discover and recovery
Reliable Transport Protocol
Dual finite state machine
protocol specific modules

EIGRP Packet types :

1.Hello
2.Acknowledgement
3.Update
4.Query
5.Reply

 By default in EIGRP hold time is three times of hello interval.

Less than T1 (1554K) =  Hello interval 5 secs  Hold time = 15 secs

Greater T1 (1554K) =  Hello interval 60 secs  Hold time = 180 secs

If required we can modify the hello interval and hold time.
To form neighbors not required to match  hello and hold time at both ends.
In OSPF to make an neighbor need to match the hello and hold time .




There are three conditions needs to met then only neighborship will be established.

1. Hello or Ack received
2. AS numbers match
3. Identical metrics ( K Values )