10 - Implementing Network Redundancy Flashcards
HSRP: Has one__ and one __ router
active, standby
HSRP: Is HSRP Cisco proprietary?
Yes
HSRP: By default the group number is _.
0
HSRP: With version 1, a group value can be any integer between _ & __.
0, 255
HSRP: All routers in HSRP group exchange ___.
hellos
HSRP: Default priority is __.
100
HSRP: Active and standby routers send hello messages to multicast address ____ udp/___
224.0.0.2 / 1985
HSRP: Verify the configuration using the ___ command.
show standby
What is the virtual MAC address for HSRPv1?
0000.0c07.acXX, where XX is the HSRP group number
____ is a parameter that enables you to choose the active router between HSRP-enabled devices in a group. The higher the ___, the higher the likelihood of becoming the active router
priority
What are some features of the active router?
- Responds to default GW ARP requests with the virtual router MAC address
- Assumes active forwarding of packets
- Sends hello messages
- Knows the virtual router IP address
What are some features of the standby router?
- Sends hello messages
- Listens for periodic hellos
- Assumes active forwarding if it does not hear from active router
HSRP group numbers are ___ significant
locally
Any router in the HSRP group that is not the active or standby is in the __ state.
listen
Whilst ARP and ping will use the HSRP virtual mac address, the router will respond to traceroute…
.. with its own mac address
Devices with the __ becomes the active router, if group priorities are the same, the device with the __will become active.
highest priority, highest IP
The default hello time is _ seconds and holdtime __ seconds, which means the failover time could be as much as _ seconds
3, 10, 10
The hold time should be at least _ times hello time
3
Hello/ holdtime is specified in seconds unless the __ keyword is used. Both are an integer of 1 to 255 unless __ is used.
msec
How do you return the hello/ hold timers to default?
No standby {group} timers
What are the 5 states of HSRP state transition?
- Initial
- Listen
- Speak
- Standby
- Active
HSRP state: the state at the start, or after a config change.
initial
HSRP state: knows the virtual IP, listens for hello messages
listen
HSRP state: router sends periodic hello messages and participates in election of active or standby router
speak
HSRP state: candidate to become next active router, sends periodic hellos
standby
HSRP state: forwards packets that are send to the group virtual mac address
active
Regardless of other router priorities or IP address, an active router will __by default
stay active
Re-election will only occur if the active router is ___.
removed
By default, the HSRP active router will lose its status only if the following occurs:
- HSRP enabled interface fails
* HSRP router itself fails
Other mechanisms to trigger HSRP active router election are as follows:
- HSRP native interface tracking
* Object tracking
What is interface tracking?
When the active routers priority is automatically decremented when an interface fails.
How is inteface tracking configured?
- Configure standby group
- Configure priority (default 100)
- Configure pre-emption on all devices within HSRP group
- Configure the tracked interfaces and decrement (default is 10) – standby 10 track interface 20
How is tracking disabled?
no standby group track
How do you verify the state of tracked interface?
Show track track_number
How do you verify if tracking is configured?
show standby
How is load sharing achieved with HSRP?
With Multigroup HSRP (MHSRP). Configure the same L3 switch to be both the spanning tree root for a VLAN and HSRP active router.
What are the two types of HSRP authentication that can be set?
Plaintext and MD5 (preferred)
What protocols does HSRP v1 support?
IPv4
What protocols doest HSRP v2 support?
IPv4, IPv6
What is the group range for HSRP v1?
0-255
What is the group range for HSRP v2?
0-4095
What is the virtual MAC address of HSRP v1?
0000.0c07.acXX
What is the virtual MAC address of HSRP v2?
0000.0c9f.fXXX
What is the multicast address of HSRP v1?
224.0.0.2
What is the multicast address of HSRP v2?
224.0.0.102
What is the default version of HSRP?
Version 1
How is HSRP v2 enabled?
standby X version 2
All devices in a HSRP group must have the __ configured otherwise hello messages are not understood
version
What are some features of VRRP?
- Open standard
- Uses plaintext or MD5 authentication
- Configuration identical to HSRP
- Verify using show vrrp command
What is the default group number for VRRP?
there isn’t one, it must be specified unlike HSRP
VRRP: if you use one of the router IP addresses as the virtual IP address, priorities are __ for electing the master.
ignored
VRRP has ___ enabled by default, compared to HSRP that has __ disabled default.
premption
A VRRP group has one __ device and multiple __ devices
master, backup
VRRP differs from HSRP in that it allows you to use an address of one of the __ VRRP group members as the virtual IP address.
physical
The __ is the only device that sends advertisements (analogous to HSRP hellos).
master
Advertisements are sent to the the multicast address ___ with protocol number __.
224.0.0.18, 112
The default advertisement interval is _ second, and the default hold time is _ seconds
1, 3
The VRRP protocol does not support __ timers, however Cisco devices allow the configuration of __ timers.
millisecond
When using millisecond values, the master advertisement value that is displayed by the show vrrp command output on the backup routers is always _ second, even though the actual value may differ
1
What are the basic setup steps for VRRP?
Interface eth0/1
Ip address x.x.x.x x.x.x.x
Vrrp 1 ip 192.168.1.1
Vrrp 1 priority 110
VRRP: how do you configure plain text auth?
vrrp group_number authentication text key_string
VRRP: how do you configure MD5 auth?
vrrp group_number authentication md5 key-string key_string
How do you verify VRRP states?
show vrrp/ show vrrp brief
What are the 3 high availability features?
- RPR
- RPR+
- SSO
What are the features of RPR?
o standby module reloads every other module, initialises all supervisor functions o Failover time is >2 minutes
What are the features of RPR+?
o standby module finishes initialising without reloading other modules o Failover time is >30 seconds
What are the features of SSO?
o Standby module is already initialised o Failover time is > 1 second
What is Cisco Nonstop Forwarding?
- Redundancy feature which can be enabled along with SSO
- NSF is an interactive method that focuses quickly on rebuilding Routing information base (RIB) after supervisor switchover
- RIB is used to generate the Forwarding information base FIB for Cisco express forwarding which is downloaded to any switch module that can perform CEF
What is Nonstop Forward with stateful switchover on Catalyst 9400
- Supports HA with NSF/SSO by allowing redundant supervisor engine to take over if a primary supervisor engine fails
- Information is continuously synced from active to standby supervisor module
- When switchover takes place, switchover time is 150ms or less
- Less than 200 ms of traffic interruption