Category: Network

BGP – iBGP and eBGP configuration

December 14, 2016 by Neel Rao

Filed under Network

Last modified December 14, 2016

If an Autonomous System has multiple BGP speakers, it could be used as a transit service for other ASs. As you see below, AS200 is a transit autonomous system for AS100 and AS300. It is necessary to ensure reachability for networks within an AS before sending the information to other external ASs. This is done by a combination of Internal BGP peering between routers inside …

Access Control List – ACL

December 12, 2016 by Neel Rao

Filed under Network

Last modified December 12, 2016

Cisco Access Control Lists are the set of conditions grouped together by name or number. These conditions are used in filtering the traffic passing from router. Through these conditions we can filter the traffic; either when it enters in router or when it exits from router. In this tutorial I will explain Cisco Access Control Lists in detail with examples. What is access control list? …

EIGRP Concepts and Operation

November 10, 2016 by Neel Rao

Filed under Network

Last modified November 10, 2016

EIGRP Concepts and Operation Like OSPF, EIGRP follows three general steps to be able to add routes to the IP routing table: Neighbor discovery: EIGRP routers send Hello messages to discover potential neighboring EIGRP routers and perform basic parameter checks to determine which routers should become neighbors. Topology exchange: Neighbors exchange full topology updates when the neighbor relationship comes up, and then only partial updates …

STP Loop Guard

November 7, 2016 by Neel Rao

Filed under Network

Last modified November 7, 2016

STP Loop Guard: Your network is suffering from regular outages. After troubleshooting, you learn that the transmit lead of a fiber uplink was damaged. Which two features can prevent the same issues in the future? (Choose two.) Root guard Loop guard BPDU guard UDLD BPDU skew detection Answer: 2 & 4  Explanation: STP Loop Guard The STP loop guard feature provides additional protection against Layer …

Which statement is true about Topology Change Notification (TCN) propagation?

November 7, 2016 by Neel Rao

Filed under Network

Last modified December 1, 2016

Which statement is true about Topology Change Notification (TCN) propagation? The originator of the TCN immediately floods this information through the network. The TCN propagation is a two step process. A TCN is generated and sent to the root bridge. The root bridge must flood this information throughout the network.  Answer: 3  Explanation: Explanation New Topology Change Mechanisms When an 802.1D bridge detects a topology …

Which statement is true about loop guard?

November 7, 2016 by Neel Rao

Filed under Network

Last modified November 7, 2016

Which statement is true about loop guard? Loop guard only operates on interfaces that are considered point-to-point by the spanning tree. Loop guard only operates on root ports. Loop guard only operates on designated ports. Loop guard only operates on edge ports. Correct answer: 1  Explanation: Understanding How Loop Guard Works: Unidirectional link failures may cause a root port or alternate port to become designated …

Securing with VLANs

November 7, 2016 by Neel Rao

Filed under Network

Last modified November 7, 2016

VLAN Access Lists Access lists can manage or control traffic as it passes through a switch. When normal access lists are configured on a Catalyst switch, they filter traffic through the use of the Ternary Content Addressable Memory (TCAM). Recall from Chapter 3, “Switch Operation,” that access lists (also known as router access lists or RACLs) are merged or compiled into the TCAM. Each ACL …

Securing Switch Access

November 7, 2016 by Neel Rao

Filed under Network

Last modified November 7, 2016

Securing Switch Access Switch AAA You can manage user activity to and through a switch with authentication, authorization, and accounting (AAA) features. AAA uses standardized methods to challenge users for their credentials before access is allowed or authorized. Accounting protocols can also record user activity on a switch. Authentication Switch or network access can be granted only after a user’s identity has been validated. User …

Spanning Tree Protocol IEEE 802.1D

November 6, 2016 by Neel Rao

Filed under Network

Last modified November 6, 2016

A robust network design not only includes efficient transfer of packets or frames but also considers how to recover quickly from faults in the network. In a Layer 3 environment, the routing protocols in use keeps track of redundant paths to a destination network so that a secondary path can be quickly utilized if the primary path fails. Layer 3 routing allows many paths to …

Virtual Router Redundancy Protocol (VRRP)

November 4, 2016 by Neel Rao

Filed under Network

Last modified November 5, 2016

Virtual Router Redundancy Protocol (VRRP)   The Virtual Router Redudnancy Protocol (VRRP) is a standards-based alternative to HSRP, defined in IETF standard RFC 2338. VRRP is so similar to HSRP, you only need to learn slightly different terminology and a couple of slight functional differences. After you understand HSRP operation and configuration, you will also understand VRRP. This section is kept brief, highlighting only the …