Direct Server Return; Routing With The Csm - Cisco catalyst 6500 series Configuration Note

Chapter 2 Networking with the Content Switching Module

Direct Server Return

Figure 2-6
Figure 2-6
Client
This configuration has these characteristics:
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Routing with the CSM

When forwarding and maintaining load-balancing connections, the CSM must make routing decisions.
However, the CSM does not run any routing protocols and does not have access to the MSFC routing
tables. The CSM builds its own routing table with three types of entries:
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OL-4612-01
shows the CSM in a direct server return configuration.
Direct Server Return
Upstream
router
VIP
High throughput or bandwidth is not required in the load balancer.
The load balancer does not recognize return traffic.
TCP flows have to be always timed-out.
TCP termination not possible (only Layer 4 load balancing).
Inband health monitoring is not possible.
Servers must be Layer 2-adjacent, with a loopback address.
Directly attached IP subnets
These are the configured on the CSM client or the server VLANs.
Default gateways
Default gateways are configured with the gateway keyword from within a client or server VLAN
configuration submode. See
511 default gateways. However, you cannot have more than seven default gateways for the same
VLAN.
Most configurations have (or can be simplified to have) a single default gateway. This gateway
points to the upstream router (or to an HSRP IP address that represents the upstream router pair),
and eventually to various static routes.
Static routes
Static routes are configured with the route keyword from within a client or server VLAN
configuration submode of configuration. See
very useful when some servers are not Layer 2 adjacent.
Catalyst
6500
MSFC
MAC
rewrite
CSM
Chapter 4, "Configuring VLANs."
Chapter 4, "Configuring VLANs."
Catalyst 6500 Series Content Switching Module Configuration Note
Routing with the CSM
Servers
In this release, you may have up to
Static routes are
2-7