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New Member

Next Hope IP and Physical Interface

Hi Experts

ip route 172.50.50.1 255.255.255.255 10.1.1.1 s0/0

why this static route has next hop IP and the physical interface also

thanks

jamil

3 REPLIES
VIP Super Bronze

Next Hope IP and Physical Interface

jamil,

You can use either the interface or the next hop command.  Some time, it is configured with both so it guarantees that the traffic always goes through that interface (in this case s0/0) and not any other interface.

HTH

New Member

Next Hope IP and Physical Interface

where the recursive lookup logic here?

Next Hope IP and Physical Interface

Hi Ibrahim,

You can read the next from a Cisco link that explains the usage of the next hop ip and/or  physical interface to static routes.

"Specifying a numerical next hop on a directly connected interface prevents the router from performing ARP or each destination address. However, if the interface with the next hop goes down and the numerical next hop is reachable through a recursive route, you should specify both the next hop IP address and the interface through which the next hop should be found. For example, ip route 0.0.0.0 0.0.0.0 Serial 3/3 192.168.20.1."

You can read more details to the link below

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800ef7b2.shtml#topic1

Regarding the ARP  for each destination and high CPU referred to the doc, you should take into consideration that with ip cef, the MAC and destination interface exist to the CEF adjacency table and can be found with just a lookup to the table (assuming that the ip cef is enabled to the router).

Hope that helps,

Vasilis

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