Category Archives: IOS


TCL in IOS. Continue reading

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OER – Optimized Edge Routing

Formally called as “Performance Routing” (PfR). Takes into account the performance statistics from the edge/border router and route dynamically based on statistics like bandwidth, delay, jitter etc.

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RIP: Routing Information Protocol in IOS

RIP: Routing Information Protocol in IOS Distance vector protocol. Routing by rumour.  Make sure “ip routing” is enabled.

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Booting cisco device from rommon

If a Cisco router  fails to load an IOS  because of less flash size/register flag/any other reason, it will stuck in the ROMMON mode. 1. To recover, You should have the IOS image in the flash/external disks.

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Network Maintenance Models: ITIL – IT Infrastructure Library – Best practice for IT service management. FCAPS – Fault, Configuration, Accounting, Performance and security – ISO model for network maintenance. TMN – Telecommunication Management Network – ITU-T adapted model of FCAPS. … Continue reading

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IP Phone

Power over Ethernet (POE): PoE devices like IP phones receive power from the connected switch. The switch can provide power in two different methods: Cisco Inline power (ILP): Cisco proprietary. IEEE 802.3af: Based on IEEE standard.

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Software and hardware redundancy

Software Redundancy: Multilayer switches act as gateway for end users. First Hop Redundancy protocols (FHRP) are available to provide redundancy to end users. FHRP includes;

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Hierarchical Network Design

Three Layer Model: Access layer: Where end users are connected. For intra-vlan routing. Distribution Layer: where access layer switches are aggregated. For inter-VLAN routing Core Layer: where distribution layer switches are aggregated. Center to all users.

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Advanced STP: RSTP and MSTP

Rapid Spanning Tree Protocol IEEE 802.1w defines RSTP. Works based on 802.1d principal concept. BPDU version field set to 2. Root bridge is elected as in 802.1d Port Roles:

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STP: 802.1d and PVST

Traditional Spanning Tree Protocol: To avoid bridging loops in L2 network with redundant paths. Defined in IEEE 802.1d standard. Bridge Protocol Data Unit (BPDU)s’ are used to communicate among all switches(bridges). SRC MAC = Mac address of the port on … Continue reading

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