Specifications

Clarifications, Known Behaviors, and Problems
ExtremeWare v6.2.1 Release Notes Page 33
VLAN boundary
Web Cache Redirection traffic must come in on an “i”-series switch running version 6.1 or better
software. Traffic that satisfies a flow redirection must otherwise have been forwarded at layer 3 (packets
must cross a VLAN boundary). For example, in a Cache Redirection application the client traffic and the
ultimate destination they wish to go to needs to cross a VLAN boundary within the switch, however
the caches themselves may reside on the client VLAN or any VLAN on the switch. In instances where
the clients and servers belong to the same subnet, the functionality can still utilized by using the proxy
ARP functionality in the switch with minimal configuration changes to clients or servers.
WCR and SLB on the Same Switch
When configuring switches to use the SLB and WCR simultaneously, users must ensure that no
overlapping L4 IP ports exist in the configuration. TCP/UDP ports must be completely independent
for WCR and SLB parameters. In this configuration, a request to a cache box cannot initiate a request
for information from a SLB VIP as this would violate the overlap of L4 ports.
Precedence of flow redirection rules
Multiple flow redirection rules can overlap in making a redirection decision. In these cases, precedence
is determined by "best match" where the most specific redirection rule that satisfies the criteria will win.
The criteria for best match is determined in the following order:
• Destination IP address/mask
• Destination IP Port or Source IP port
• Source IP address/mask
In general, the following rules apply:
• If a flow with a comparatively better matching mask on an IP address satisfies the content of a
packet, that flow will be observed.
• If one flow redirection rule contains ’any’ as an L4 protocol and a second flow redirection rule
contains explicit L4 port information, the second will be observed if the packet contains matching L4
information.
• If one flow has a comparatively better match on source information and a second flow has
comparatively better match on destination information then the rule with the better match on the
destination information will be selected.
For example, in the following 2 cases, the rule with the best match (using the above criteria) is the rule
that is selected.
Example 1:
In this case, Rule 1 is the rule with the best match as it contains an explicit Destination IP Port even
though the mask for the Destination IP Address is less specific.
Example 2:
Destination IP Address Destination IP Port Source IP Address Priority Selection
192.0.0.0/8 80 ANY 1
192.168.0.0/16 ANY ANY 2
Destination IP Address Destination IP Port Source IP Address Priority Selection