High Availability Flashcards

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1
Q

Graceful restart works by informing OSPF neighbors that it is going to restart. The router that is going to restart is called the _________________

A

restarting router

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2
Q

(OSPF) the restarting process is called the _____________

A

graceful restart mode

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3
Q

Graceful restart initiates by sending a link-local type _ LSA called the grace LSA with a specified time called the ________

A

9, grace period

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4
Q

Two adjacent routers enter helper mode and are called the __________

A

helper neighbors

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5
Q

OSPF graceful restart is covered in RFC 3623. Before the RFC, Cisco already implemented its own version of graceful restart called ___________. Cisco IOS supports both NSF and the RFC version of graceful restart.

A

NSF (Non-Stop Forwarding)

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6
Q

Graceful shutdown - It is possible to shut down the OSPF process using ________ command and at interface level you may use _______ command

A

Shutdown, ip ospf shutdown

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7
Q

MPLS LDP GR functions strictly in ______ ____, which means it can only help other routers that are enabled with MPLS SSO/NSF and GR to recover. If the router with LDP GR fails, its peer routers cannot help it recover.

A

helper mode

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8
Q

The basic operation of LDP GR /NSF is the same as other protocols. Routers continue forwarding packets even after the LDP adjacency fails.

A

True

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9
Q

An adjacency between router LDP GR > LDP SSO/NSF > LDP GR is invalid

A

False, it is true

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10
Q

When a failure occurs and LDP GR/NSF is enabled, the entries in the LFIB are marked as stale, after the LDP session recovers the flag is removed

A

True

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11
Q

The Router announces the GR capable via Fault Tolerant flag during the session establishment

A

Partially false, the announcement is via TLV FT and not flag

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12
Q

MPLS LDP GR is supported in _________. ________________ sessions are not supported. Only LDP sessions are supported. MPLS LDP GR cannot be configured on label-controlled ___ (LC-___) interfaces.

A

strict helper mode, Tag Distribution Protocol (TDP), ATM

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13
Q

MPLS LDP GR configuration: SUMMARY STEPS 1. enable configure terminal ip cef [distributed] __________________

A

mpls ldp graceful-restart

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14
Q

Control plane could stop functioning altogether and because the forwarding plane is a separate entity with its own processors it can continue forwarding packets based on its copy of the FIB. This is ________ ______ ______ (_ _ _): The ability of the forwarding plane to continue running “headless” if the control plane stops.

A

Non-Stop Forwarding (NSF)

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15
Q

_ _ _ allows you to switch from a primary to a backup control plane without disrupting forwarding. The FIB could still become invalid during the period between when the primary control plane goes down and the backup control plane takes over, but the risk in this period is usually an acceptable compromise

A

NSF

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16
Q

The backup control plane maintains a copy of the active configuration and current state on system components such as interfaces, it can become active much faster than if it had to learn all this information first. That, then, is the second ring of our acronym circus: Cisco calls this ____ ____ ____ (_ _ _)

A

Stateful Switchover (SSO)

17
Q

Briefly describe the function of Non Stop Routing and graceful restart

A

Both aim to prevent routing protocol reconvergence. They keep routing going during an RP switchover

18
Q
A

s

19
Q

For which protocols is graceful restart available?

A

OSPF, BGP, ISIS, LDP

20
Q

Consider a BGP PE NSR Capable x CE NSR non capable Session, in case of switchover between PE RPs will the BGP session drop?

A

No, NSR transfers operation to another RP

21
Q

To run BGP NSR the L3VPN must be configured

A

True

22
Q

How should bfd for ospf be configured at the interface level

A

ip ospf bfd (only active) bfd interval 50 min_rx 50 multiplier 3

23
Q

How should bfd for isis be configured at the interface level

A

isis bfd (only active) bfd interval 50 min_rx 50 multiplier 3

24
Q

How should a bundle be configured in static mode

A

channel-group 12 mode on

25
Q

What is the result of the configurations below: channel-group 12 mode auto channel-group 12 mode auto

A

No channel

26
Q

What is the result of the configurations below: channel-group 12 mode desirable channel-group 12 mode auto

A

Channel OK PAGP

27
Q

What is the result of the configurations below: channel-group 12 mode active channel-group 12 mode auto

A

No channel

28
Q

What is the result of the configurations below: channel-group 12 mode active channel-group 12 mode passive

A

Channel OK LACP

29
Q

Graceful restart must be enabled on both peers for NSF to operate

A

True. In the case of NSR, it supports one of the endpoints if the CE in an L3 VPN environment does not support NSR

30
Q

In which BGP message will the NSF / graceful restart capability be announced

A

open

31
Q

Before enabling NSF, SSO must be enabled

A

True

32
Q

NSF is supported for both IPv4 and IPv6

A

False, only IPv4

33
Q

NFS does not support multicast routing

A

True, Multicast is not SSO aware

34
Q

HSRP is supported along with NSF

A

False

35
Q

SSO can operate using RPs with different IOS versions

A

False, the versions must be the same

36
Q

How to enable NSF in bgp?

A

router bgp 100 bgp graceful-restart

37
Q

Default restart graceful-restart timer

A

120 secs

38
Q

How to enable NSF in eigrp? How to enable NSF in ospf? How to enable NSF in isis?

A

router eigrp 100 nsf router ospf 100 nsf In isis it is necessary to inform which standard R2(config-router)#nsf? cisco Checkpoint method ietf IETF method R2(config-router)#nsf