Author Archives: Mrityunjay Singh

All about MTU and Fragmentation.

Posted on May 19, 2020 by Mrityunjay Singh

Topology So, in this post we will cover the mtu and fragmentation cases. So, every interface/port have its capacity to send data across the line or port. So, the Maximum transfer unit (MTU). When I say MTU it usually means … Continue reading →

Posted in IPv4 | 1 Comment

GARP(Gratuitous Address resolution Protocol)

Posted on May 17, 2020 by Mrityunjay Singh

Gratuitous ARP is either request or reply packet that is needed in some cases. usually when we assigned any ip on interface or host boot the first packet it send is GARP. GARP packet have Sender and Target IP address … Continue reading →

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TCP/IP Details

Posted on May 17, 2020 by Mrityunjay Singh

TCP Header Format Total 13 Field Learn acronym HSDDDO Acche SE UR WINNER RE PAD FLAG—UPARSF

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BGP Route-Reflector Design

Posted on January 1, 2020 by Mrityunjay Singh

A route learned by one ibgp peer won’t be advertised to another ibgp peer. This is called BGP split horizon rule. This rule is used to avoid loop in ibgp cases. To mitigate this, we have following option by which … Continue reading →

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Types of Address resolution Protocol(ARP)

Posted on March 7, 2019 by Mrityunjay Singh

Topology Address resolution Protocol is used to find the Layer 2( mac address) information when the layer 3(IP) Information is already given. Total 9 filed in Header. The typical Address resolution protocol Header format is shown as below Fig1 ARP_Header

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Different Static Route Options

Posted on March 3, 2019 by Mrityunjay Singh

In this scenario router IOU1 already know the outgoing interface as we configured the ip route specifying the outgoing interface. So here IOU1 wil check the routing table and will get the outgoing interface detail in single lookup.

Since the network is Ethernet, the IOU1 must know the L2 address, so it will construct ARP packet having source IP address of PC1 and destination of 30.30.30.2. Source mac of IOU e0/1 interface and DMAC as 0.0.0.0. Continue reading →

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OSI MODEL

Posted on November 27, 2017 by Mrityunjay Singh

OSI Stands for open system interconnection model.  This is reference or virtual model, you cannot see it , touch it ,but its exists conceptually just like electron, protons etc. OSI model is invented by ISO(International standard organization). ISO is non … Continue reading →

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Site to Site IPsec VPN

Posted on November 26, 2017 by Mrityunjay Singh

Topology Summary: To implement Flex VPN or IPSEC VPN the topology shown above. The motive is to make the reachability between LAN to LAN network i.e from 20.20.20.0 to 30.30.30.0 & vice versa. Currently we have configure simple connectivity in … Continue reading →

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Gre Tunnel

Posted on October 2, 2017 by Mrityunjay Singh

Topology Objectives Create Gre tunnel between Router A and Router c. We are creating tunnel to internal communication between two LAN segments without, advertising LAN IP in internet domain. Steps: Your end to end network should be reachable i.e the … Continue reading →

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MPLS lsp path broken

Posted on September 24, 2017 by Mrityunjay Singh

Topology: Objective: To test the broken LSP failover using LDP protocol. All router in the topology are running under OSPF area 0.LDP has been enabled between them. Currently LDP synced and LDP neighbor ship has been established between all routers.

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MPLS Vpn Working Principle

Posted on September 19, 2017 by Mrityunjay Singh

Topology: Objective: Configure MPLS L3VPN and understand it’s working. Currently PE1 & PE2 running iBGP under AS 100.PE1, P1, P2 & PE2 running OSPF as IGP. MPLS backbone running LDP for label distribution, LDP neighbor ship has been established among … Continue reading →

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Multicast Overview

Posted on September 13, 2017 by Mrityunjay Singh
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BGP Weight Attribute

Posted on September 11, 2017 by Mrityunjay Singh

Topology Objectives Use BGP attribute to influence the route selection in BGP. Currently Router R1/R1 running iBGP .Between R1-R3 & R2-R4 ebgp is used. Within ISP we have used Full iBGP mesh ( of course we could have used RR).Connect … Continue reading →

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BGP Initialization

Posted on September 10, 2017 by Mrityunjay Singh

Topology Objectives Objective is to understand how bgp initialize when you enable interfaces and bgp parameters. We will check it by sniffing tool Wireshark to know what happening behind the scene.  Wireshark will be enabled on f0/0 on R2.

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BGP Over GRE

Posted on September 10, 2017 by Mrityunjay Singh

Topology Objective: To implement BGP over GRE , the topology shown above. In topology R1 & R3 running BGP 100 whereas R2 running only IGP.R1-R4 & R3-R5 running ebgp and advertising prefix 4.4.4.4 and 5.5.5.5 respectively. R1-R2-R3 running ospf under … Continue reading →

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