Specifications

D-Link xStack Switch Series: Meeting the Need at the Edge of the Network 11
D-Link Systems, Inc.
October 2004
Secure Shell 2 (SSH2)
xStack Switches support SSH2 to securely transfer switch configurations and images into and
out of the switch. To fix the known limitations in SSH, it is critical that customers use the latest
SSH2 as supported in the xStack Series.
Virtual Router Redundancy Protocol (VRRP) Support
D-Link's xStack supports Virtual Router Redundancy Protocol (VRRP), allowing several Layer
3 switches on a multi-access link to utilize the same virtual IP address. VRRP support provides
convenience, permitting your host system to be configured manually or via DHCP with a single
default gateway.
VRRP is used in the D-Link DES-6500 and the xStack Series Switch products for high
availability. Each subordinate switch with routing capability is initialized and ready to take over
routing functions if the master fails. Each subordinate switch is fully initialized and connected to
the master. The subordinates have identical interface addresses, encapsulation types, and
interface protocols and services. The subordinate switches continually receive and integrate
synchronized configuration information sent by the current master and monitor their readiness to
operate through the continuous execution of self-tests. Re-establishment of routes and links
happens more quickly than in normal Layer 3 devices because of the lack of time needed to
initialize the routing interfaces.
Multiple Mechanisms for High Availability
The D-Link xStack technology supports a variety of mechanisms for creating high resiliency in a
stack.
• Cross-Stack Link Aggregation technology—Multiple switches in a stack can create an
link aggregation connection. Loss of an individual switch will not affect connectivity for
the other switches.
• Master redundancy—Every switch in the stack can act as the master. If the current
master fails, another master is elected from the stack.
• Stacking cable resiliency—When a break in the bi-directional loop occurs, the switches
automatically begin sending information over the half of the loop that is still intact. If
the entire 40Gbps of bandwidth is being used, QoS mechanisms will control traffic flow
to keep jitter and latency-sensitive traffic flowing while throttling lower priority traffic.
• Distributed Layer 2 forwarding—In the event of a master switch failure, individual
switches will continue to forward information based on the tables they last received
from the master.
• VRRP for Layer 3 resiliency—Each switch is initialized for routing capability and is
ready to be elected as master if the current master fails. Subordinate switches are not
reset so that Layer 2 forwarding can continue uninterrupted.