Riverstone Networks WICT1-12 - Manual (Page 192)

11-14 Riverstone Networks RS Switch Router User Guide Release 8.0
Configuring Router Discovery IP Routing Configuration Guide
11.15.4 Using Custom Forwarding with Other RS Features
Custom forwarding profiles are used to wildcard certain fields in the IP header. This can cause incompatibility with
various RS features that require that these fields not be wild carded. Therefore, whenever custom forwarding is enabled
on a port, the RS checks for compatibility with other features that the port supports. Conversely, when a feature is
applied to an interface or VLAN with ports in custom forwarding mode, the RS also checks for compatibility.
Access Control Lists (ACLs)
An ACL specifies various fields on the IP header which it uses to filter out packets. Thus, when an ACL is applied to
an interface, the RS checks to see if any of the ports on the interface have custom forwarding enabled. For any port in
which custom forwarding is enabled, the RS makes an additional check that the fields specified in the ACL are not
wild carded by the custom forwarding profile. If this happens, the RS generates an error. Conversely, when a port in
custom forwarding mode is added to an interface, VLAN or SmartTrunk, the RS checks for compatibility between the
custom profile and the existing ACLs.
Network Address Translation (NAT)
NAT requires the source IP address and sometimes the source socket for address translation. Thus, the RS checks if
the source IP and source socket are wild carded whenever NAT is enabled on an interface or a custom forwarding
profile is applied to a NAT enabled interface.
Rate Limiting
Rate limiting uses ACLs to limit traffic rate. Thus, the RS performs a compatibility check when a port is requires to
support both custom forwarding and rate limiting.
Quality of Service (QoS)
QoS policies applied at L3, require certain fields in the IP header, such as source IP and destination IP. The RS performs
a compatibility check when a QoS policy is applied to a port in forwarding mode .
L4 Bridging
L4 bridging is incompatible with custom forwarding profiles. Therefore a port cannot support l4 bridging and custom
forwarding at the same time.
11.16 CONFIGURING ROUTER DISCOVERY
The router discovery server on the RS periodically sends out router advertisements to announce the existence of the
RS to other hosts. The router advertisements are multicast or broadcast to each interface on the RS on which it is
enabled and contain a list of the addresses on the interface and the preference of each address for use as a default route
for the interface. A host can also send a router solicitation, to which the router discovery server on the RS will respond
with a unicast router advertisement.