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

Part VI: Implementing High Availability

Layer 3 High Availability

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

Hot Standby Router Protocol HSRP HSRP is a Cisco proprietary protocol RFC 2281 The routers exchange HSRP hello messages at regular intervals multicast destination 224.0.0.2 (“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.

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

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 0000.0c07.acxx, where xx represents the HSRP group HSRP Group 1 appears as 0000.0c07.ac01 HSRP Group16 appears as 0000.0c07.ac10 Switch A Switch B Switch-A(config)# interface vlan 50 Switch-A(config-if)# ip address 192.168.1.10 255.255.255.0 Switch-A(config-if)# standby 1 priority 200 Switch-A(config-if)# standby 1 preempt Switch-A(config-if)# standby 1 ip 192.168.1.1 Switch-A(config-if)# no shutdown Switch-B(config)# interface vlan 50 Switch-B(config-if)# ip address 192.168.1.11 255.255.255.0 Switch-B(config-if)# standby 1 priority 100 Switch-B(config-if)# standby 1 preempt Switch-B(config-if)# standby 1 ip 192.168.1.1 Switch-B(config-if)# no shutdown

Load Balancing with HSRP

Hot Standby Router Protocol HSRP Switch A Switch B Switch-A(config)# interface vlan 50 Switch-A(config-if)# ip address 192.168.1.10 255.255.255.0 Switch-A(config-if)# standby 1 priority 200 Switch-A(config-if)# standby 1 preempt Switch-A(config-if)# standby 1 ip 192.168.1.1 Switch-A(config-if)# standby 1 authentication MyKey Switch-A(config-if)# standby 2 priority 100 Switch-A(config-if)# standby 2 ip 192.168.1.2 Switch-A(config-if)# standby 2 authentication MyKey Switch-B(config)# interface vlan 50 Switch-B(config-if)# ip address 192.168.1.11 255.255.255.0 Switch-B(config-if)# standby 1 priority 100 Switch-B(config-if)# standby 1 ip 192.168.1.1 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 192.168.1.2 Switch-B(config-if)# standby 2 authentication MyKey

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 0000.5e00.01xx 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 224.0.0.18 (VRRP), using IP protocol 112

Virtual Router Redundancy Protocol VRRP Switch A Switch B Switch-A(config)# interface vlan 50 Switch-A(config-if)# ip address 192.168.1.10 255.255.255.0 Switch-A(config-if)# vrrp 1 priority 200 Switch-A(config-if)# vrrp 1 ip 192.168.1.1 Switch-A(config-if)# vrrp 2 priority 100 Switch-A(config-if)# no vrrp 2 preempt Switch-A(config-if)# vrrp 2 ip 192.168.1.2 Switch-B(config)# interface vlan 50 Switch-B(config-if)# ip address 192.168.1.11 255.255.255.0 Switch-B(config-if)# vrrp 1 priority 100 Switch-B(config-if)# no vrrp 1 preempt Switch-B(config-if)# vrrp 1 ip 192.168.1.1 Switch-B(config-if)# vrrp 2 priority 200 Switch-B(config-if)# vrrp 2 ip 192.168.1.2

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 1023. 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

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

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]

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]

Gateway Load Balancing Protocol

Gateway Load Balancing Protocol

Gateway Load Balancing Protocol Switch A Switch B Switch C interface vlan 50 ip address 192.168.1.10 255.255.255.0 glbp 1 priority 200 glbp 1 preempt glbp 1 ip 192.168.1.1 ip address 192.168.1.11 255.255.255.0 glbp 1 priority 150 ip address 192.168.1.12 255.255.255.0 glbp 1 priority 100

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