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entry in CEF .

jitenshah18
Beginner
Beginner

This is a part of the CEF output . How is the attached entry different from last entry where Prefix and Nexthop are equal ?

1. Does not the last entry indicate its a connected/attached route ?

2. Also for the receive entries means those packets are meant for the router ? if they are meant for the router ,  how does the router determine what needs to be done with this packet. Can you give a example.

please note I do not have any configuration of the router.

---sho ip cef---

Prefix              Next Hop             Interface

172.20.104.144/30   attached             FastEthernet0/0.3010

172.20.104.144/32   receive

172.20.104.145/32   receive

172.20.104.146/32   172.20.104.146       FastEthernet0/0.3010

1 Accepted Solution

Accepted Solutions

Harold Ritter
Cisco Employee
Cisco Employee

Hi Jiten,

1. The last entry indicates a cached adjacency, which means that arp has been resolved for this specific host route.

2. Correct. "Receive" means that these host routes belong to the local router. Packets received with these addresses as destination will be locally processed.

Regards

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

View solution in original post

3 Replies 3

Harold Ritter
Cisco Employee
Cisco Employee

Hi Jiten,

1. The last entry indicates a cached adjacency, which means that arp has been resolved for this specific host route.

2. Correct. "Receive" means that these host routes belong to the local router. Packets received with these addresses as destination will be locally processed.

Regards

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

Thanks Harold. so that means for question 1 - So can that indicate its a connected route ? Just curiuos to know why this entry is here.

Hi Jiten,

Yes, it is a connected route for a neighbor for which the arp has already been processed and cached. It is there so that we do not need to go through that same processed as long as the entry is valid.

Regards

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
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