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Miscellaneous Questions

November 2nd, 2019 Go to comments

Question 1

Explanation

Nonstop Forwarding (NSF) works with Stateful switchover (SSO) to minimize the amount of time a network is unavailable to its users following a switchover. The main objective of Cisco NSF is to continue forwarding IP packets following a route processor (RP) switchover.

Usually, when a networking device restarts, all routing peers of that device detect that the device went down and then came back up. This transition results in what is called a routing flap, which could spread across multiple routing domains. Routing flaps caused by routing restarts create routing instabilities, which are detrimental to the overall network performance. Cisco NSF helps to suppress routing flaps in SSO-enabled devices, thus reducing network instability.

Cisco NSF allows for the forwarding of data packets to continue along known routes while the routing protocol information is being restored following a switchover. With Cisco NSF, peer networking devices do not experience routing flaps. Data traffic is forwarded through intelligent line cards while the standby RP assumes control from the failed active RP during a switchover. The ability of line cards to remain up through a switchover and to be kept current with the Forwarding Information Base (FIB) on the active RP is key to Cisco NSF operation.

Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SY/configuration/guide/sy_swcg/nonstop_forwarding.html#wp1102552

Question 2

Question 3

Question 4

Explanation

IP Phones are trusted devices. In the current Cisco implementation, the intelligent exchange of information is performed through the Cisco Discovery Protocol (CDP). When a Catalyst switch detects an IP Phone via CDP and can instruct the phone to extend a trust boundary to its auxiliary data port. The voice traffic from the phone should be implicitly trusted because the phone is both a Cisco device and a small switch that can be configured and controlled.

Reference: CCNP BCMSN Exam Certification Guide

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Question 9

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