1. CCNP-SWITCHING 300-115 Mohamed Samir YouTube channel Double CCIEs #27042(R/S&SP)

2. Part VI: Implementing High Availability

3. Layer 3 High Availability

4. several approaches to providing router redundancy
Hot Standby Router Protocol (HSRP)
Virtual Router Redundancy Protocol (VRRP)
Gateway Load Balancing Protocol (GLBP)

5. Hot Standby Router Protocol HSRP
HSRP is a Cisco proprietary protocol RFC 2281
The routers exchange HSRP hello messages at regular intervals
multicast destination (“all routers”) using UDP port 1985.
group number, from 0 to 255
most Catalyst switches support only up to 16 unique HSRP group numbers
HSRP groups are locally significant only on an interface.
If all router priorities are equal highest IP address on the HSRP interface becomes the active
By default, hellos are sent every 3 seconds.

6. Hot Standby Router Protocol
Change hello timer
Switch(config-if)# standby group timers [msec] hello [msec] holdtime
Switch(config-if)# standby 1 timers msec 100 msec 300
Preemption
By default it is not configured
Switch(config-if)# standby group preempt [delay [minimum seconds] [reload
seconds]]
Authentication
Switch(config-if)# standby group authentication string
Switch(config-if)# standby group authentication md5 key-string [0 | 7] string
Switch(config)# key chain chain-name
Switch(config-keychain)# key key-number
Switch(config-keychain-key)# key-string [0 | 7] string
Switch(config)# interface type mod/num
Switch(config-if)# standby group authentication md5 key-chain chain-name

7. Hot Standby Router Protocol HSRP
Conceding the Election
Switch(config-if)# standby group track type mod/num [decrementvalue]
decrementvalue for an interface is 10.
HSRP Gateway Addressing
HSRP defines a special MAC address of the form c07.acxx, where xx represents the HSRP group
HSRP Group 1 appears as c07.ac01
HSRP Group16 appears as c07.ac10
Switch A
Switch B
Switch-A(config)# interface vlan 50
Switch-A(config-if)# ip address
Switch-A(config-if)# standby 1 priority 200
Switch-A(config-if)# standby 1 preempt
Switch-A(config-if)# standby 1 ip
Switch-A(config-if)# no shutdown
Switch-B(config)# interface vlan 50
Switch-B(config-if)# ip address
Switch-B(config-if)# standby 1 priority 100
Switch-B(config-if)# standby 1 preempt
Switch-B(config-if)# standby 1 ip
Switch-B(config-if)# no shutdown

8. Load Balancing with HSRP

9. Hot Standby Router Protocol HSRP
Switch A
Switch B
Switch-A(config)# interface vlan 50
Switch-A(config-if)# ip address
Switch-A(config-if)# standby 1 priority 200
Switch-A(config-if)# standby 1 preempt
Switch-A(config-if)# standby 1 ip
Switch-A(config-if)# standby 1 authentication MyKey
Switch-A(config-if)# standby 2 priority 100
Switch-A(config-if)# standby 2 ip
Switch-A(config-if)# standby 2 authentication MyKey
Switch-B(config)# interface vlan 50
Switch-B(config-if)# ip address
Switch-B(config-if)# standby 1 priority 100
Switch-B(config-if)# standby 1 ip
Switch-B(config-if)# standby 1 authentication MyKey
Switch-B(config-if)# standby 2 priority 200
Switch-B(config-if)# standby 2 preempt
Switch-B(config-if)# standby 2 ip
Switch-B(config-if)# standby 2 authentication MyKey

10. Virtual Router Redundancy Protocol VRRP
standards-based IETF standard RFC 2338.
The active router called master router, others called backup state
The virtual router MAC address e00.01xx where xx is group no.
By default, all VRRP routers are configured to preempt the current master router if their priorities are greater.
VRRP advertisements are sent at 1-second intervals
multicast destination address (VRRP), using IP protocol 112

11. Virtual Router Redundancy Protocol VRRP
Switch A
Switch B
Switch-A(config)# interface vlan 50
Switch-A(config-if)# ip address
Switch-A(config-if)# vrrp 1 priority 200
Switch-A(config-if)# vrrp 1 ip
Switch-A(config-if)# vrrp 2 priority 100
Switch-A(config-if)# no vrrp 2 preempt
Switch-A(config-if)# vrrp 2 ip
Switch-B(config)# interface vlan 50
Switch-B(config-if)# ip address
Switch-B(config-if)# vrrp 1 priority 100
Switch-B(config-if)# no vrrp 1 preempt
Switch-B(config-if)# vrrp 1 ip
Switch-B(config-if)# vrrp 2 priority 200
Switch-B(config-if)# vrrp 2 ip

12. Gateway Load Balancing Protocol
(GLBP) is a Cisco proprietary protocol designed to overcome the limitations of existing redundant router protocols
Active Virtual Gateway AVG
highest priority value, or the highest IP address in the group
The AVG answers all ARP requests for the virtual router address
assigns the necessary virtual MAC addresses to each of the routers in GLBP group up to 4 virtual MAC
Each of these routers is referred to as an active virtual forwarder (AVF)
Switch(config-if)# glbp group priority level
GLBP group numbers range from 0 to The router priority can be 1 to 255 (255 is the highest priority), defaulting to 100
Switch(config-if)# glbp group preempt [delay minimum seconds]
Switch(config-if)# glbp group timers [msec] hellotime [msec] holdtime
You can configure it on AVG router only

13. Gateway Load Balancing Protocol
Active Virtual Forwarder AVF
Each router participating in the GLBP group can become an AVF, if the AVG assigns it that role.
The virtual MAC addresses always have the form 0007.b4xx.xxyy
xx.xx represents six 0 bits followed by a 10-bit GLBP group number
The 8-bit yy value is the virtual forwarder number
GLBP uses the periodic hello messages to detect AVF failures
The redirect timer is used to determine when the AVG will stop using the old virtual MAC address in ARP replies.
Switch(config-if)# glbp group timers redirect redirect timeout

14. Gateway Load Balancing Protocol
GLBP uses thresholds to determine when a router can and cannot be the AVF.
Switch(config-if)# glbp group weighting maximum [lower lower] [upper upper]
Switch(config)# track object-number interface type member/module/number {lineprotocol | ip routing}
Switch(config-if)# glbp group weighting track object-number [decrement value]

15. GLBP Load Balancing
You can use one of the following load-balancing methods in a GLBP group:
Round robin : This is the default method used by GLBP.
Weighted
Host dependent:
Switch(config-if)# glbp group load-balancing [round-robin | weighted | host-dependent]

16. Gateway Load Balancing Protocol

17. Gateway Load Balancing Protocol

18. Gateway Load Balancing Protocol
Switch A
Switch B
Switch C
interface vlan 50
ip address
glbp 1 priority 200
glbp 1 preempt
glbp 1 ip
ip address
glbp 1 priority 150
ip address
glbp 1 priority 100

19. Any questions ?

20. Thank you for your time ! 
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