CCNP Switch 300-115 Study Guide – First Hop Redundancy Protocols

I recently sat my CCNP 300-115 – Switch exam. I spent months taking notes on all of the important information needed to pass the exam. This study guide focuses on all things related to First Hop Redundancy Protocols.

Please see other study Guides –

HSRP

  • Timers hello 3 secs hold 10 secs- timers do not need to match
  • HSRP v1 and HSRP v2 use different multicast addresses for hello packets
  • HSRP version 1 uses the multicast IP address 224.0.0.2
  • HSRP version 2 uses the multicast IP address of 224.0.0.102
  • It supports authentication
  • The VIP must be in the same subnet as the primary IP address
  • An IP must be configured on the Interface
  • HSRP states that an Active router takes when it is preempted by a higher priority router? Speak
  • Default configuration statements – the standby track interface decrements is 10, standby hold time id 10 seconds, the standby priority is 100
  • Command to configure HSRP group as a slave of another HSRP group – #Standby follow
  • For HSRP to become active on an interface the VIP must be on the same subnet as the primary IP address and an IP must be configured on the Interface.
  • Two tasks to configure multiple HSRP client groups – Use the standby follow command, use the standby mac-refresh <seconds> command
  • When a HSRP active router is preempted by a higher priority router it enters the Speak state.
  • A standby HSRP router becomes active if it has a higher priority than the current active.
  • Three HSRP exchange states used in multicast messages – Coup, Hello, Resign
  • HSRP authentication methods – MD5 authentication and Plain Text authentication
  • Two types of tracking thresholds – Percentage and Weight
  • HSRP extension that allows groups to share traffic loads – MHSRP
  • HSRP – is the protocol specified by RFC 2281 provides network redundancy for IP networks ensuring that user traffic immediately and transparently recovers from first hop failures in network edge devices or access circuits.
  • HSRP allows one router to automatically assume the function of the second router if the second router fails.
  • State in which the standby virtual gateway takes election – listen
  • 3 design types of capable Ethernet LANs does HSRP support. – multiaccess, multicast, broadcast
  • Which hot standby group numbers are used in HSRP token ring – 0,1 and 2
  • Feature that is automatically enabled when configuring HSRP – ICMP redirect
  • Command to quickly view HSRP state – #show standby brief
  • #no standby priority – command sets the default priority of 100
  • Priority value range that can be assigned – 0-255
  • HSRP group 37 MAC address – 00:00:0c:07:ac:25
  • When a HSRP router is preempted by a higher priority router it enters the Speak state
  • MHSRP – HSRP extension that allows groups to share traffic loads
  • When 2 routers in a HSRP standby group are configured with Identical priorities, the router with the highest configured address will become the active router.

VRRP

  • Supports plain text and MD5 authentication (also no authentication)
  • Can track multiple objects at a time
  • VRRP uses the multicast IP address of 224.0.0.18 with up protocol 112
  • VRRP uses protocol identifier 112
  • VRRP can use an interface IP address as the virtual IP address
  • VRRP advertisements are sent only from the master router and they include priority information
  • Which kind of tracking can you do in VRRP – route, interface state
  • Virtual router mac address – 0000.5e00.000a
  • A VRRP backup virtual router becomes the master router if its priority is higher than the priority of the current master router.
  • Virtual Router Master is responsible for forwarding packets that are sent to the IP addresses of the virtual router.
  • VRRP can track only one object at a time.
  • 000.5e00.0101 – last 2 digits of the virtual routers MAC address indicate the group number
  • VRRP master is the only one that sends out advertisements

GLBP

  • Timers hello 3 secs hold 10 secs-
  • The AVG assigns virtual MAC addresses to GLBP group members
  • The AVG responds to ARP requests for the Virtual IP address
  • Only GLBP performs load balancing.
  • GLBP Default load balancing scheme – Per host basis using round robin scheme
  • Maximum number of virtual mac addresses per group – 4
  • GLBP can cause layer 2 loops
  • GLBP members communicate between each other through a Multicast address of 224.0.0.102
  • Active Virtural Gateway role responsible for answering arp requests for the virtual IP address in GLBP.
  • Uses multicast address 224.0.0.102 and port 3222
  • Only 1 active virtual gateway can be elected on a switch
  • a backup GLBP active virtual gateway can become active only if the current AVG fails
  • GLBP uses UDP port 3222 (source and destination for hello messages).
  • The AVG assigns virtual MAC address to GLBP group members
  • 3 authentication methods used by GLBP – MD5, no authentication, plain text
  • If an AVF has failed, one of the secondary virtual forwarders in the listen state assumes responsibility for the virtual MAC address
  • GLBP supports up to 1024 virtual routers per group
  • Benefits of GLBP – it can load share LAN traffic across up to 4 AVFs in a GLBP group, it can automatically adjust group weighting when an interface goes down.
  • Member devices must elect exactly one AVG
  • The AVG assigns virtual MAC addresses to all group members
  • If standby AVG has a higher priority it becomes the new active router
  • GLBP can automatically adjust group weighting when an interface goes down

6 comments

Leave a Reply