06-03-2013 09:25 AM - edited 03-07-2019 01:42 PM
C 192.17.10.64/29 is directly connected, Vlan572
This is a directly connected route entry in the RIB. So if we have a packet with destination 'X' which matches this route then the next hop for destination will be 'X' itself ?
thanks.
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06-03-2013 09:28 AM
Yes. If this layer 3 switch receives a packet for X with that entry in the routing table then the next hop is X. The switch will then look in its ARP table and if it finds an entry for X it will use that MAC address as the destination MAC and forward directly to the device. If it does not find an entry in the ARP table then it will issue an arp request for the IP address and try to learn an entry to add to the ARP table.
HTH
Rick
06-03-2013 09:34 AM
Hi Jiten,
If your destination is a connected network then router doesn't use the next hop rather it does arp requested on the connected interface to find the destination location. In sort in order to reach any destination which is in the same subnet of connected interfaces router uses MAC address.
Hope that helps
Regards
Najaf
Please rate when applicable or helpful !!!
06-03-2013 09:28 AM
Yes. If this layer 3 switch receives a packet for X with that entry in the routing table then the next hop is X. The switch will then look in its ARP table and if it finds an entry for X it will use that MAC address as the destination MAC and forward directly to the device. If it does not find an entry in the ARP table then it will issue an arp request for the IP address and try to learn an entry to add to the ARP table.
HTH
Rick
06-03-2013 09:45 AM
thanks Rick so in this case the packets next hop field is not altered right ?
06-03-2013 09:34 AM
Hi Jiten,
If your destination is a connected network then router doesn't use the next hop rather it does arp requested on the connected interface to find the destination location. In sort in order to reach any destination which is in the same subnet of connected interfaces router uses MAC address.
Hope that helps
Regards
Najaf
Please rate when applicable or helpful !!!
06-03-2013 09:46 AM
Najaf you mean it does an arp request for destination 'X' according to my question right ?
06-03-2013 09:50 AM
Yes that is right Jiten
Hope that helps
Regards
Najaf
Please rate when applicable or helpful !!!
06-03-2013 10:16 AM
so it wont alter the Next Hop field in the IP header in this case ?
06-03-2013 10:39 AM
Perhaps I am not understanding something in your question and if so please provide clarification.
There is not a field in the IP header for next hop. The next hop is determined by the layer 3 device that is forwarding the packet. But the next hop information is not carried in the IP header of the packet.
HTH
Rick
06-03-2013 10:46 AM
Mybad. I forgot there is not next hop filed in IP header.
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