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IP CEF Questions

Hi,

Is there anybody who knows the definition of attached, connected and receive in the following context:

2600_Router_1# show ip cef 1.1.1.1 detail

1.1.1.1/32, version 12, connected, receive

2600_Router_1# show ip cef 10.10.10.1 detail

10.10.10.1/32, version 9, receive

2600_Router_1# show ip cef 20.20.20.1 detail

20.20.20.1/32, version 1, receive

20.20.20.2/32, version 16, connected, cached adjacency 20.20.20.2

0 packets, 0 bytes

via 20.20.20.2, Serial0/0, 0 dependencies

next hop 20.20.20.2, Serial0/0

valid cached adjacency

I saw loopback address defined as connected and receive but also seen physical interface locally configured on the router being defined as only receive, I am not to sure about the exact definition of connected and receive.

What is the meaning of the 0 packets and 0 bytes

If we have the following information:

2600_Router_1#show ip cef adjacency ser0/0 20.20.20.2

Prefix Next Hop Interface

30.30.30.0/24 20.20.20.2 Serial0/0

Can we assume that we have a CEF entry for 30.30,30.0, 30,30,30.1,.... 30.30.30.254, 30.30.30.255

Thanks

Stéphane

1 REPLY
Hall of Fame Super Silver

Re: IP CEF Questions

Hello Stephane,

>> 600_Router_1#show ip cef adjacency ser0/0 20.20.20.2

Prefix Next Hop Interface

30.30.30.0/24 20.20.20.2 Serial0/0

Can we assume that we have a CEF entry for 30.30,30.0, 30,30,30.1,.... 30.30.30.254, 30.30.30.255

your understanding is a correct a FEC (Fowarding equivalence class) for prefix 30.30.30.0/24 is present in CEF table with exit interface ser0/0 and IP next-hop 20.20.20.2

receive is the correct state for a connected IP subnet

the router might be distinguishing loopback interface because it cannot be reached from outside.

on a Cisco 6500 running 12.2(33)SXH5 I see receive flag for both loopbacks and SVIs

sh ip cef 10.54.7.0

10.54.7.0/32

  receive for Vlan14

sh ip cef 10.80.0.149

10.80.0.149/32

  receive for Loopback5

sh ver | inc image

System image file is "disk0:s72033-advipservicesk9_wan-mz.122-33.SXH5.bin"

on a remote C6500 I can see for the first prefix:

sh ip cef 10.54.7.0

10.54.7.0/24

  nexthop 10.82.0.37 TenGigabitEthernet6/1

Hope to help

Giuseppe

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