cef...

this is great stuff... cef in practical use...  i will not attempt to restate this, it is so well done... but i will show output...

from ccnp tshoot net acad lab man:

i have to repeat; after this i will have done all three net acad lab man's, and this is the best... of course it's the logical conclusion (or new beginning)... if you are attempting ccnp, these are an absolute must...

i am so glad i have this... makes me want to re-read russ white's cef book...

To verify the correct operation of the multilayer switching process, first verify that the control plane information is accurately reflected in the software FIB and adjacency table. Next, verify that the information from the FIB and
adjacency table is correctly compiled into the TCAM.

DLS1#sh ip cef 10.1.202.1
10.1.202.1/32
  nexthop 10.1.2.2 FastEthernet0/5
 
DLS1#sh adj f0/5 det
Protocol Interface                 Address
IP       FastEthernet0/5           10.1.2.2(18)
                                   0 packets, 0 bytes
                                   epoch 0
                                   sourced in sev-epoch 2
                                   Encap length 14
                                   001906E7ACC00016C70696C20800
                                   L2 destination address byte offset 0
                                   L2 destination address byte length 6
                                   Link-type after encap: ip
                                   ARP
DLS1#



that highlighted number above looks formidable, however:

 
DLS1#sh ip arp 10.1.2.2
Protocol  Address          Age (min)  Hardware Addr   Type   Interface
Internet  10.1.2.2              143   0019.06e7.acc0  ARPA   FastEthernet0/5


and:

DLS1#sh int f0/5 | i bia
  Hardware is Fast Ethernet, address is 0016.c706.96c2 (bia 0016.c706.96c2)


plus 0800 for ethertype... more below...


The show ip cef command can be used in a similar way as the show ip route command. When you specify a destination IP address as an option to the command, it lists the entry in the Cisco Express Forwarding FIB that
matches that IP address. It also shows the next-hop IP address and egress interface, which serve as a pointer to the adjacency table.
 
The show adjacency command can be used to display the information contained in the adjacency table. The next-hop IP address or interface can be specified to select specific adjacencies. Adding the detail keyword to the command shows the frame rewrite information for packets that are switched through that adjacency. The frame rewrite information lists the complete Ethernet header. For the example in the output, this consists of the destination MAC address 001B.530D.6029 (which is the same MAC address that was listed as the MAC address of next hop 10.1.2.14 in the ARP cache), followed by the source MAC address 0017.5A53.A3C2 (which equals the MAC address of the egress interface F0/5), and finally, the Ethertype 0x0800 (which indicates that the protocol contained in the Ethernet frame is IP version 4). 

The information displayed in these show commands should accurately reflect the information in the routing table
and ARP cache.



you need this book...