Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 116)

For FastIron SX devices only, traffic coming from a tunnel can be filtered by an ACL both before and
after the tunnel is terminated and also redirected by PBR after tunnel is terminated. An ACL classifies
and sets QoS for GRE traffic. If the ACL or PBR is applied to the tunnel loopback port, it would apply
to the inner IP packet header (the payload packet) after the tunnel is terminated. If the ACL is applied
to the tunnel ingress port, then the delivery header (outer header) would be classified or filtered before
the tunnel is terminated.
NOTE
Restrictions for using ACLs in conjunction with GRE are noted in the section
Configuration
considerations for GRE IP tunnels on page 116. PBR can be configured on tunnel loopback ports for
tunnel interfaces with no restrictions. PBR with GRE tunnel is not supported on FSX 800 and FSX
1600 with the SX-FI48GPP module.
Syslog messages related to GRE IP tunnels
Syslog messages provide management applications with information related to GRE IP tunnels. The
following Syslog message is supported.
Tunnel: TUN-RECURSIVE-DOWN tnnl 1, Tnl disabled due to recursive routing
Configuration considerations for GRE IP tunnels
Before configuring GRE tunnels and tunnel options, consider the configuration notes in this section.
• When GRE is enabled on a Layer 3 switch, the following features are not supported on Virtual
Ethernet (VE) ports, VE member ports (ports that have IP addresses), and GRE tunnel loopback
ports:
‐ ACL logging
‐ ACL statistics (also called ACL counting)
‐ MAC address filters
‐ IPv6 filters
NOTE
The above features are supported on VLANs that do not have VE ports.
• Whenever multiple IP addresses are configured on a tunnel source, the primary address of the
tunnel is always used for forming the tunnel connections. Therefore, carefully check the
configurations when configuring the tunnel destination.
• When a GRE tunnel is configured, you cannot configure the same routing protocol on the tunnel
through which you learn the route to the tunnel destination. For example, if the FastIron learns the
tunnel destination route through the OSPF protocol, you cannot configure the OSPF protocol on the
same tunnel and vice-versa. When a tunnel has OSPF configured, the FastIron cannot learn the
tunnel destination route through OSPF. This could cause the system to become unstable.
• The tunnel destination cannot be resolved to the tunnel itself or any other local tunnel. This is called
recursive routing. This scenario would cause the tunnel interface to flap and the Syslog message
TUN-RECURSIVE-DOWN to be logged. To resolve this issue, create a static route for the tunnel
destination.
Syslog messages related to GRE IP tunnels
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