gratuitous arp and secundary ip addresses

Answered Question
Mar 13th, 2009
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When an interface (SVI or routed) comes up, does a Cisco switch or router send a gratuitous arp to update the arp cache of the hosts on that subnet ? I guess yes (?), BUT does he also do this for each secundary address or secundary HSRP active address that is configured on the interface ?


regards,

Geert

Correct Answer by Richard Burts about 8 years 1 week ago

Geert


I set up a test of this using a pair of 1841 routers with a secondary address configured on a FastEthernet interface. The test shows that when the FastEthernet interface is taken down and brought up that the router does send a gratuitous arp for both the primary address and the secondary address.


HTH


Rick

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Correct Answer
Richard Burts Fri, 03/13/2009 - 11:30
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Geert


I set up a test of this using a pair of 1841 routers with a secondary address configured on a FastEthernet interface. The test shows that when the FastEthernet interface is taken down and brought up that the router does send a gratuitous arp for both the primary address and the secondary address.


HTH


Rick

gnijs Fri, 03/13/2009 - 15:16
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Rick,


Thanks for your test.


Geert

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