Netwoking Tutorials

AD value of protocols

2014-01-19T07:02:00.001-08:00

Connected interface	0
Static route	1
Enhanced Interior Gateway Routing Protocol (EIGRP) summary route	5
External Border Gateway Protocol (BGP)	20
Internal EIGRP	90
IGRP	100
OSPF	110
Intermediate System-to-Intermediate System (IS-IS)	115
Routing Information Protocol (RIP)	120
Exterior Gateway Protocol (EGP)	140
On Demand Routing (ODR)	160
External EIGRP	170
Internal BGP	200
Unknown*	255

L&T Interview questions : 15-01-2014

2014-01-15T07:29:00.001-08:00

1. EIGRP port number ?

2. Explain EIGRP active and passive state

3. What is EIGRP advertised distance

4. BGP attributes ?

5. STP parameters ?

6. What is stub area and totally stub area ?

Routing protocols V/S Routed protocols

2014-01-14T21:48:00.001-08:00

Routing protocols

Routing protocols will help to a router find best route towards network and it will advertise the routes .

Ex. RIP,EIGRP,OSPF,BGP

Routed protocols

Routed protocols used for transport data across the network .

Ex. ip ,ipx,telnet,snmp,smtp

XL Healthcare interview

2014-01-12T07:05:00.001-08:00

Position: Lead Network Engineer

Experience: 4-6yrs

Description Of Work:

This position is responsible for the design and operational support of XLHealth LAN/WAN data network

infrastructure. Responsibilities include, disaster recovery planning and advanced technical problem

resolution for multiple locations based out of Bangalore and Hyderabad

Duties & Responsibilities:

ESSENTIAL:

- Develops short and long range network design and architecture plans for XLHealth facilities and

data centers.

- Develops configuration standards across network equipment in order to ensure integrity of the

systems and services.

- Manages network related projects, tasks and upgrades and coordinates networking resources

as needed.

- Reviews new technologies, methodologies and processes to ensure the network infrastructure

meets current and future needs.

- Maintains information technology inventory records of wide-area and local-area network

hardware and software as well as coordination of repairs and quality control tests.

- Should have strong knowledge in switching (VLAN, VTP, STP, HSRP), routing (OSPF, BGP)

configuration and troubleshooting.

- Should have hands-on knowledge in firewalls (CISCO ASA 55XX SERIES) configuration and

troubleshooting

- A good understanding of WAN accelerators (Citrix Branch Repeaters/Cisco WAAS/Riverbed) and

Cisco ACS server.

- Lead should also be responsible to document, follow change request processes on day-to-day

bases.

- Must – A very good communication both verbal and written

HCL interview : 12/1/2014

2014-01-12T02:59:00.004-08:00

1. What is the difference between routed protocols and routing protocol ?

2. What is prempt in HSRP.

3. What is default priority of a port in STP ?

4. L2 protocols

5. How many bit used for IPv6 ?

6. How traceroute works ?

7. What is difference between default route and dynamic route

VLANS

2012-03-29T20:01:00.000-07:00

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

2012-03-28T01:28:00.000-07:00

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

2012-03-25T21:07:00.002-07:00

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

2012-03-25T21:06:00.000-07:00

/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

2012-03-23T06:53:00.002-07:00

CCIE number starts from 1025.

INTERVIEW QUESTIONS

2012-03-21T07:29:00.001-07:00

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

2012-03-21T05:46:00.000-07:00

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)

2012-03-21T05:30:00.000-07:00

VLAN - IEEE 802.1q

STP ( Spanning Tree Protocol)

2012-03-21T05:27:00.001-07:00

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 )

2012-03-21T04:57:00.000-07:00

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

2012-03-21T04:37:00.001-07:00

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)

2012-03-20T00:31:00.000-07:00

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 )

SHORT FORMS USED IN MAIL

2012-03-19T22:14:00.000-07:00

SOW- Statements of work
RMA - Risk Management Association
RFO - Reason For Outage
MoM - Minutes of Meeting
PFA - Please Find the Attachment
FYI - For your information
FYA - For your attention
EOD - End of the Day
ETA - Estimated Time of Arrival
FE - Feild Engineer
RCA - Root Cause Analysis
ETR - Expected time of return
HA - High Availability
SLA - Service Level Agreement

Ethernet Switching

2012-03-13T05:34:00.000-07:00

Layer 3 topology

Layer 2 Ether Cahanel

Router on Stick

Port Security

To configure trunking and assign vlan numbers.

Interface Types

L2 Switch ports

Access
Trunk
Dynamic
Tunnel

L3 ports

switched virtual interface ( SVI )
Native Routed interface

L2 and L3 VPN

2012-03-12T11:13:00.002-07:00

1. What is the difference between L2 VPN and L3 VPN.

L2 VPN

ISP devices forward the frames according to L2 information. (DLCI,MAC,VLAN ID )
Enterprise stays in control of L3 policies ( Routing , Q0S)

L3 VPN

ISP devices will forward the packets according to L3 information.( IP addresses)
ISP involved in Customer IP routing.
IP specific

HSRP ( HOT STANDBY ROUTER PROTOCOL)

2011-10-06T04:07:00.000-07:00

HSRP is a cisco proprietary protcol , VRRP (Virtual Redundancy Router Protocol) is the open standard used for redundancy RFC 3768.

HSRP process have 6 states .

1. Initial

This will happens in only two time , once the config change done and after router reboot.

2. Learn

3. Listen

4. Speak

5.Stand by

6. Active

Config :

R1(config-if)# standby 100 ip 192.168.100.1
R1(config-if)# standby 100 priority 100
R1(config-if)# standby 100 track fa 0/0/1 /* This will track the interface , if its down decrement the priority *|
R1(config-if)# standby 100 preempt /* This will ensure highest priority router is the active one. *\

Practicing Network routing and swicthing

2010-09-29T05:30:00.000-07:00

http://www.gns3.net/

Download the GNS3 its one of the best router simulator .
Those who preparing CCNA,CCNP,CCSP,CCIP exams its best tool to practice

VPN

2010-08-14T01:56:00.001-07:00

A well-designed VPN can greatly benefit a company. For example, it can:

Extend geographic connectivity
Improve security
Reduce operational costs versus traditional WAN
Reduce transit time and transportation costs for remote users
Improve productivity
Simplify network topology
Provide global networking opportunities
Provide telecommuter support
Provide broadband networking compatibility
Provide faster ROI (return on investment) than traditional WAN

What features are needed in a well-designed VPN? It should incorporate:

Security
Reliability
Scalability
Network management
Policy management

A VPN supports at least three different modes of use:

Remote Access (RAS) VPN - Under this application only a single VPN gateway is involved. The other party involved in negotiating the secure communication channel with the VPN Gateway is a PC or laptops that is connected to the Internet and running VPN Client software. The VPN Client allows telecommuters and traveling users to communicate on the central network and access servers from many different locations.

Benefit : Significant cost savings by reducing the burden of long distance charges associated with dial-up access. Also helps increase productivity and peace of mind by ensuring secure network access regardless of where an employee physically is.

Site-to-Site Intranet VPN - With Intranet VPN, gateways at various physical locations within the same business negotiate a secure communication channel across the Internet known as a VPN tunnel. An example would be a network that exists in several buildings connected to a data center or mainframe that has secure access through private lines. Users from the networks on either side of the tunnel can communicate with one another as if it were a single network. These may need strong encryption and strict performance and bandwidth requirements.

Benefit : Substantial cost savings over traditional leased-line or frame relay technologies through the use of Internet to bridge potentially long distances between sites.

Site-to-Site Extranet VPN - Almost identical to Intranets, except they are meant for external business partners. As such, firewall access restrictions are used in conjunction with VPN tunnels, so that business partners are only able to gain secure access to specific data / resources, while not gaining access to private corporate information.

Benefit : Businesses enjoy the same policies as a private network, including security, QoS, manageability, and reliability.

VPN tunneling

logical connection to Client and server.

The packets will encapsulated with tunneling protocol,later packet will De-encapsulted at client.
Tunneling Protocols
1.PPTP - point to point tunneling protocol. working L2
Developed microsoft and security issues.
2.L2TP -Layer 2 tunneliny - woring in l2
Enhanced PPTP with security features by cisco -
3. IP sec - working @ L3
4.Socks
These protocols will do encryption and authentication.IPSEC -
Encrytption - DES,3DES,MD5 DH ( Diffe Helman )
Authentication : SHA1,MD5,RSA
crypto ipsec transform-set
<name> ah-md5-hmac esp-des
show crypto isakmp sa