Nortel SMC 2450, Руководство по внедрению

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Maintenance Page 175 of 260
Secure Multimedia Controller Implementation Guide
3 Perform the initial setup procedure. See “Configuring the initial SMC” on
page 82 .
End of Procedure
VRRP overview
The Virtual Router Redundancy Protocol (VRRP) eliminates single point of
failure by dynamically assigning responsibility for a virtual router to one of
the physical routers on a LAN. VRRP provides a higher availability default
path without requiring configuration of dynamic routing or router discovery
protocols on every end-host.
IMPORTANT!
VRRP is defined by RFC 2338; however, VRRP on the SMC is a custom
implementation that deviates from RFC 2338 in the following ways:
• To verify a host is down before failover, VRRP uses its own checking
mechanism.
• To limit the number of failovers when a device goes down and comes
back up, VRRP does not support preferred master.
The SMC does not work with Spanning Tree Protocol (STP) because
STP interferes with VRRP. When STP is enabled, the SMC host with the
highest IP address always become master. This leads to two failovers if
the master SMC fail: the first failover occurs when the master fails and
the second failover occurs when it restarts. This double failover is due to
a race condition between the VRRP advertisements and the
reconverging STP. The rebooted machine may not receive the
advertisements from the new master prior to its becoming master itself,
thereby leading to a master-master election process.
Note 1: If any of the six SMC ports are connected to an L2 switch, the
master election process occurs when STP-enabled Layer-2 switch link is
failed over. A single port pair behaving as previously described invokes
the master election process behavior.
Note 2: In VRRP election, the only relevant IP address is the cluster
MIP address.