Configuring IP
December 2005 © Foundry Networks, Inc. 16 - 7
NOTE: You cannot add static entries to the IP forwarding cache, although you can increase the number of
entries the cache can contain. See the section “Displaying and Modifying System Parameter Default Settings” on
page 4-8.
To increase the size of the IP forwarding cache, see the section “Displaying and Modifying System Parameter
Default Settings” on page 4-8.
Layer 4 Session Table
The Layer 4 session provides a fast path for forwarding packets. A session is an entry that contains complete
Layer 3 and Layer 4 information for a flow of traffic. Layer 3 information includes the source and destination IP
addresses. Layer 4 information includes the source and destination TCP and UDP ports. For comparison, the IP
forwarding cache contains the Layer 3 destination address but does not contain the other source and destination
address information of a Layer 4 session table entry.
The Layer 2 Switch or Layer 3 Switch selects the session table instead of the IP forwarding table for fast-path
forwarding for the following features:
• Layer 4 Quality-of-Service (QoS) policies
• IP access policies
To increase the size of the session table, see the section “Displaying and Modifying System Parameter Default
Settings” on page 4-8. The ip-qos-session parameter controls the size of the session table.
IP Route Exchange Protocols
Foundry Layer 3 Switches support the following IP route exchange protocols:
• Routing Information Protocol (RIP)
• Open Shortest Path First (OSPF)
• Border Gateway Protocol version 4 (BGP4)
All these protocols provide routes to the IP route table. You can use one or more of these protocols, in any
combination. The protocols are disabled by default. For configuration information, see the following:
• “Configuring RIP” on page 17-1
• “Configuring OSPF” on page 20-1
• “Configuring BGP4” on page 21-1
IP Multicast Protocols
Foundry Layer 3 Switches also support the following Internet Group Membership Protocol (IGMP) based IP
multicast protocols:
• Protocol Independent Multicast – Dense mode (PIM-DM)
• Protocol Independent Multicast – Sparse mode (PIM-SM)
• Distance Vector Multicast Routing Protocol (DVMRP)
For configuration information, see “Configuring IP Multicast Protocols” on page 19-1.
NOTE: Foundry Layer 2 Switches support IGMP and can forward IP multicast packets. See the chapter
“Configuring IP Multicast Traffic Reduction” .
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