Allied Telesis 86251-08 manual Adopting the Vrrp IP Address

56 SHOW IP ADVERTISE Patch Release Note

Adopting the VRRP IP Address

Benefits The VRRP master router can adopt the IP address of the virtual router (VR), and respond to the following packets destined for the VR IP address, even if it does not own this IP address on any of its interfaces:

■ICMP echo requests (pings)

■Telnet and SSH connection requests

■HTTP and SSL GUI management requests

■SNMP requests, and

■DNS relay requests

VRRP IP Address Adoption allows continuous accessibility of the VR IP address even as the VR master changes. Using this feature:

■You can easily tell whether the VR is functioning, by pinging the single VR IP address.

■You can easily monitor the performance of the VR, regardless of which participating router is acting as master.

■DNS relay can continue functioning via the same IP address at all times.

Risks When VR IP Address Adoption is used, the master router accepts packets destined for the virtual router, even though it may not own this IP address. This does not conform to RFC 2338. Because the same IP address refers to different devices at different times, there is a risk of confusion arising. This risk can be reduced by a suitable network management policy.

Recommendations Before using VR IP address adoption, consider the following guidelines to avoid confusion:

■Ensure that the VR has an IP address that is different from the interface IP addresses of any of the individual routers in the VR.

■Ensure that all routers in the virtual router use VRRP IP Address Adoption (or that none do).

■Use the VR IP address to monitor the VR master. Be aware that this does not give information about one particular participating router, but about the current VR master, whichever participating router is acting as the master at the time.

■When changing the configuration of the participating routers using Telnet, GUI or SNMP, configure each device individually by pointing to their individual IP addresses.

■When changing the configuration of the participating routers, do not use the VR IP address. Only one device, the VR master, is responding to this IP address, and you may not know which device it is.

Configuration To configure VR IP Address Adoption, use the new parameter, ADOPTVRIP, that has been added to the CREATE VRRP and SET VRRP commands:

CREATE VRRP=vr-identifier OVER=physical-interface IPADDRESS=ipadd [ADOPTVRIP={ONOFF}] [other-vrrp- parameters]

SET VRRP=vr-identifier[ADOPTVRIP={ONOFF}] [other-vrrp-

parameters]

Patch 86251-08 for Software Release 2.5.1 C613-10356-00 REV I