sh arp on router

Answered Question
Mar 31st, 2010
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Hi all,


I did sh arp on router


2650xm#sh arp
Protocol  Address          Age (min)  Hardware Addr   Type   Interface
Internet  96.51.x.x          -   000f.8f6d.7e60  ARPA   FastEthernet0/0
Internet  192.168.1.40           95   000b.be59.cc60  ARPA   FastEthernet1/0
Internet  192.168.1.11          199   0015.e9cf.190b  ARPA   FastEthernet1/0
Internet  192.168.1.10          224   000b.bece.bbc0  ARPA   FastEthernet1/0
Internet  192.168.1.1             -   000f.8f6d.7e70  ARPA   FastEthernet1/0
Internet  192.168.1.3             8   0026.c64a.b844  ARPA   FastEthernet1/0
Internet  96.51.145.70           38   0013.46d2.fb11  ARPA   FastEthernet0/0
Internet  96.51.144.1             0   0011.20a8.04a7  ARPA   FastEthernet0/0


Here 96.51.x.x is ip of fa0/0 interface of my router and it directly connects to cable modem


96.51.144.1 is my next hop route.


my question is why i see  - under age for fa0/0 interface ip of my router and 0 for next hop ip  96.51.144.1 ?


They do not change remail same - and 0 under age field.


mahesh

Correct Answer by Jon Marshall about 7 years 1 month ago

Mahesh


The age time in the output is the amount of time the entry has been cached without being renewed. Because there is constant traffic from your router to the next-hop the cache will forever be being renewed so that is why you see it as 0 most of the time.


Jon

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Jon Marshall Wed, 03/31/2010 - 05:51
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Mahesh


- under the age field simply means the address is local to the router ie. it is configured on the router.


Jon

mahesh18 Wed, 03/31/2010 - 05:57
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Hi Jon

thanks for reply yes that is correct

so what does 0 mean under age field?


mahesh

Correct Answer
Jon Marshall Wed, 03/31/2010 - 06:11
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Mahesh


The age time in the output is the amount of time the entry has been cached without being renewed. Because there is constant traffic from your router to the next-hop the cache will forever be being renewed so that is why you see it as 0 most of the time.


Jon

mahesh18 Wed, 03/31/2010 - 06:20
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H Jon


Many thanks again for your explanation


regards

mahesh

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