135:: This adjacency is created when the router knows that either the destination IP's subnet is directly connected to the router itself and it does not know that destination device's MAC address, or the router knows the IP address of the router to forward a packet to for a destination, but it does not know that router's MAC address. Packets that trigger this entry will generate an ARP request.
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for its FIB entry. The MAC address is the IP address's MAC address if the destination's subnet is directly connected to the router, or is the MAC address of the router that the packet needs to be sent to if the destination's subnet is not directly connected to the router currently processing the
117:: This type of entry handles packets whose final destinations include the router itself. This includes packets whose IP addresses are assigned to the router itself, broadcast packets, and multicasts that have set up the router itself as one of the destinations.
161:), where there is a FIB table on each of the line cards. This avoids the need for querying the main processor or routing table in order to get the next-hop information. Instead, fast switching will be performed on the line card itself.
129:: Deals with packets that require special handling or that cannot be switched by CEF. Such packets are forwarded to the next switching layer (generally fast switching) where they can be processed and hopefully forwarded correctly.
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123:: Handles packets destined to a NULL interface. Packets with FIB entries pointing to NULL adjacencies will normally be dropped.
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speed by reducing the overhead and delays introduced by other routing techniques. CEF consists of two key components: The
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maintains layer 2 or switching information linked to a particular FIB entry, avoiding the need for an
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99:(ARP) request for each table lookup. There are several types of adjacencies. Some are listed below:
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or high-capacity routers offer a similar functionality where layer-3 switching or
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147:: Packets pointing to this entry are dropped, but the prefix will be checked.
106:: This type of entry contains the correct outbound interface and the correct
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to enhance the overall network performance. Although CEF is a Cisco
141:: FIB entries pointing to this type of adjacency will be discarded.
88:, maintaining only the next-hop address for a particular IP-route.
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In order to take full advantage of CEF, it is recommended to use
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IP Switching Cisco
Express Forwarding Configuration Guide
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is similar to the routing table generated by multiple
202:CEF (Cisco Express Forwarding) site (link broken)
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53:) instead of by software and the (central)
29:switching technology used mainly in large
207:Choosing the best routing switching path
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71:Forwarding Information Base (FIB)
232:Packets (information technology)
65:CEF is mainly used to increase
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16:Layer 3 switching technology
97:Address Resolution Protocol
49:is done in hardware (in an
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164:CEF currently supports
25:(CEF) is an advanced
43:multi-layer switches
39:proprietary protocol
227:Telecommunications
23:Express Forwarding
139:Discard adjacency
115:Receive adjacency
86:routing protocols
41:other vendors of
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67:packet switching
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153:distributed CEF
133:Glean adjacency
104:Cache adjacency
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170:Frame Relay
108:MAC address
75:adjacencies
221:Categories
190:Cisco HDLC
166:Ethernet
61:Function
35:Internet
186:tunnels
111:packet.
47:routing
33:or the
27:layer 3
188:, and
21:Cisco
182:FDDI
158:dCEF
91:The
80:The
73:and
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178:PPP
174:ATM
82:FIB
55:CPU
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