Abstract. SGS; Reviewed: WCH/MIC 2/20/2003. Solution & Interoperability Test Lab Application Notes 2003 Avaya Inc. All Rights Reserved.

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1 Deploying a Virtual Router Redundancy Protocol (VRRP) Strategy Between an Avaya P330 Multilayer Switch and an Avaya P580/P882 MultiService Switch with Multiple Masters - Issue 1.0 Abstract Network Managers may use an IETF standard for router redundancy known as Virtual Router Redundancy Protocol (VRRP). VRRP is designed to eliminate the single point of failure inherent in the static default routed environment. These Application Notes explain how to configure VRRP between an Avaya P330 Multilayer Switch and an Avaya P580/P882 MultiService Switch. 1 of 9

2 1. Introduction These Application Notes describe how to configure VRRP between an Avaya P332GT-ML Multilayer Switch and an Avaya P580 MultiService Switch as illustrated in Figure 1. In this example, the Avaya P332GT-ML switch and the Avaya P580 switch share a common network, /24, and exchange VRRP information through an Avaya P333T Stackable Switch. The Avaya P333T switch is acting as a generic Layer 2 switch with all default settings and is not described in detail here. Two end nodes, PC 1 and PC 2, are load balanced between two different default gateways, on the Avaya P332GT-ML switch and on the Avaya P580 switch. If anything should happen to either switch, VRRP will tell the surviving switch to act as the default gateway of the affected switch. Although these Application Notes show the Avaya P332GT-ML switch, the Avaya P333R Multilayer Switch or the Avaya P332G-ML Multilayer Switch supports the same configuration. Likewise, even though an Avaya P580 switch is used here, the Avaya P882 MultiService Switch also supports the same configuration. VRRP works independently of any routing protocol. For completeness, RIP version 2 configurations are shown to communicate with the corporate network. However, OSPF or any other supported routing protocol may be used Background The Virtual Router Redundancy Protocol (VRRP) is designed to eliminate the single point of failure inherent in the static default routed environment. VRRP specifies an election protocol that dynamically assigns responsibility for a virtual router to one of the VRRP routers on a LAN. The VRRP router controlling the IP addresses associated with a virtual router is called the Master, and it forwards packets sent to these IP addresses. The election process provides dynamic fail-over in the forwarding responsibility, should the Master become unavailable. Any of the virtual router s IP addresses on a LAN can then be used as the default first hop router by end-hosts. The advantage gained from using VRRP is a higher availability default path without requiring configuration of dynamic routing or router discovery protocols on every end-host. VRRP specifies an election protocol to provide the virtual router function. All protocol messaging is performed using IP multicast datagrams, so the protocol can operate over a variety of multi-access LAN technologies supporting IP multicast. Each VRRP virtual router has a single well-known MAC address allocated to it. The virtual router MAC address is used as the source in all periodic VRRP messages sent by the Master router to enable bridge learning in an extended LAN. A virtual router is defined by its virtual router identifier (VRID) and a set of IP addresses. A VRRP router may associate a virtual router with its real addresses on an interface, and may also be configured with additional virtual router mappings and priority for virtual routers it is able to back up. The mapping between VRID and addresses must be coordinated among all VRRP routers on a LAN. However, there is no restriction against reusing a VRID with a different 2 of 9

3 address mapping on different LANs. The scope of each virtual router is restricted to a single LAN. To minimize network traffic, only the Master for each virtual router sends periodic VRRP Advertisement messages. A Backup router will not attempt to preempt the Master unless it has higher priority. This eliminates service disruption unless a more preferred path becomes available. It is also possible to administratively prohibit all preemption attempts. The only exception is that a VRRP router will always become Master of any virtual router associated with addresses it owns, as illustrated in these Application Notes. In other words, if the VRRP address is the same address as the interface address then the VRRP interface will automatically become the Master. If the Master becomes unavailable, then the highest priority Backup will transition to Master after a short delay, providing a controlled transition of the virtual router responsibility with minimal service interruption. VRRP can be configured in one of two ways. In the first, there is a single active Master router and a Backup router, or multiple Backup routers. This is simple, but expensive, since the second router is only used during fail-over. The second way is illustrated in this document, and employs multiple master routers and backup routers. This is more complex, but utilizes the second router. For example, in a two-router environment both routers can be Master and Backup routers for each other. In this case, the end nodes can have their default gateways divided between the two routers. This is a much more desirable configuration as each router is utilized, and is load balancing network traffic. End nodes can be manually assigned to the two different gateways, or they can use a common split DHCP scope configuration in order to automatically receive the different default gateways on the same segment. 3 of 9

4 Corporate Network /24 Avaya P580 Multi Access Switch /24 Avaya P332GT-ML Multilayer Switch Master DG: Backup DG: Avaya P333T Master DG: Layer 2 Switch Backup DG: End Node PC 1 IP: DG: End Node PC 2 IP: DG: Figure 1: An IP network using VRRP to backup default gateways for end nodes. 2. Equipment and Software Validated The following equipment and software were used for the sample configuration provided: Equipment Software Avaya P332GT-ML Multilayer Switch Avaya P580 MultiService Switch Avaya P333T Modular Stackable Switch Configure the Avaya P332GT-ML Switch Below is the configuration of the Avaya P332GT-ML switch. Explanatory comments are on the right and are proceeded by : session router Avaya Inc. P330-ML Switch - Router configuration 4 of 9

5 version set vlan 1 name "v1" set vlan 3 name "v3" router vrrp Turn on VRRP, Globally interface "vlan1" ip vlan name "v1" ip address ip vrrp 1 VRID is 1 ip vrrp 1 address Shares the same IP address as the interface. Owner of Interface will become the Master automatically and its priority will be 255 by default ip vrrp 2 VRID is 2 ip vrrp 2 address be 100 by default interface "vlan3" ip vlan name "v3" ip address ip rip rip-version 2 router rip network network Backup VRRP Interface and its priority will 4. Configure the Avaya P580 Switch Below is the configuration of the Avaya P580 switch.. Explanatory comments are on the right and are proceeded by : set vlan 1 name "vlan1" set vlan 3 name "vlan3" hostname "P580-A" router vrrp Globally enables VRRP Begin Module 4 configuration module 4 begin type M8508_1000 set port category 4/1 user-port set port vlan 4/1 1 set port vlan 4/2 3 module 4 end End Module 4 configuration interface "vlan1" ip address ip vlan name "vlan2" ip rip send version 2 ip rip receive version 2 ip vrrp Turn on VRRP for this interface 5 of 9

6 ip vrrp 1 address VRID is 1. Backup interface and its priority will be 100 by default ip vrrp 2 address VRID is 2. Shares the same IP address as the interface. Owner of Interface will become Master automatically and its priority will be 255 by default interface "vlan3" ip address ip vlan name "vlan3" ip rip send version 2 ip rip receive version 2 ip bootp-dhcp server router rip network network Additional Commands These commands are common to all Avaya Switches listed in these Application Notes. Ip vrrp <vr-id> timer <value> Use the ip vrrp timer command to set the virtual router advertisement timer value (in seconds) for the virtual router ID. Use the no form of this command to restore the default value. value The advertisement transmit time (seconds). Ip vrrp <vr-id> priority <pri-value> Use the ip vrrp priority command to set the virtual router priority value used when selecting a master router. Use the no form of this command to restore the default value. pri-value The priority value. The range is of 9

7 Ip vrrp <vr-id> auth-key <key-string> Use the ip vrrp auth-key command to set the virtual router simple password authentication for the virtual router ID. Use the no form of this command to disable simple password authentication for the virtual router instance. key-string Simple password string. Ip vrrp <vr-id> preempt Use the ip vrrp preempt command to configure the router to preempt a lower priority master for the virtual router ID. Use the no form of this command to disable preemption for the virtual router instance. By default, preemption is enabled. ip vrrp priority Command Use the ip vrrp priority command to set the virtual router priority value used when selecting a master router. Use the no form of this command to restore the default value. pri-value The priority value. The range is Ip vrrp <vr-id> primary <ip-address> Use the ip vrrp primary command to set the primary address that will be used as the source address of VRRP packets for the virtual router ID. Use the no form of this command to return to the default primary address for the virtual router instance. By default, the primary address is selected automatically by the device. ip-address Primary IP address of the virtual router. This address should be one of the router addresses on the VLAN. Ip vrrp <vr-id> override addr owner Use the ip vrrp override addr owner command to accept packets addressed to the IP address(es) associated with the virtual router, such as ICMP, SNMP, and TELNET (if it is not the IP address owner). Use the no form of this command to discard these packets. 7 of 9

8 6. Verification To verify the VRRP state of the P332GT-ML switch, type: session router show ip vrrp The machine will respond with: LAN VRID IP Address Pri Timer State Since MASTER 00:00: BACKUP 01:35:10 To verify the VRRP state of the P580 switch, type: show ip vrrp The machine will respond with: Interface VRID IP Address Pri Timer State Since vlan BACKUP 13:59:29 vlan MASTER 13:59:18 The column headers in the previous two commands are: Column Interface (P580 only): LAN (P332GT-ML only): VRID: IP Address: PRI: Timer: State: Since: Description Name of IP Interface Associated VLAN ID Virtual Router ID. Multiple VRIDs can be assigned per interface VRRP IP Address VRRP Priority from 0 (lowest) to 255 (Highest). Virtual Router Advertisement Timer (in seconds). 1 is default. Current state of VRRP process. Choices are Initialize, Master, and Backup Time of last state change 7. Conclusion In summary, VRRP is designed to eliminate the single point of failure inherent in the static default routed environment. Network managers that deploy Avaya switches can be assured of a reliable network in case of a fail-over situation. 8. Additional References P332GT-ML User s Guide at P580/882 User Guide at P580/882 Command Reference Guide at Virtual Router Redundancy Protocol (VRRP); RFC at 8 of 9

9 Avaya and the Avaya Logo are trademarks of Avaya Inc. All trademarks identified by and are registered trademarks or trademarks, respectively, of Avaya Inc. All other trademarks are the property of their respective owners. The information provided in these Application Notes is subject to change without notice. The configurations, technical data, and recommendations provided in these Application Notes are believed to be accurate and dependable, but are presented without express or implied warranty. Users are responsible for their application of any products specified in these Application Notes. Please any questions or comments pertaining to these Application Notes along with the full title name and filename, located in the lower right corner, directly to the Avaya Solution & Interoperability Test Lab at 9 of 9