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Recursive table lookup
19 years 10 months ago #7230
by Apostolis
Recursive table lookup was created by Apostolis
Hello!
Does anyone know what is recursive table lookup? Why use it?
Is it a way that static routing works? Can you give me an example?
Thank you
Does anyone know what is recursive table lookup? Why use it?
Is it a way that static routing works? Can you give me an example?
Thank you
19 years 10 months ago #7263
by Apostolis
Replied by Apostolis on topic Re: Recursive table lookup
Anyone? I really need some help!
19 years 10 months ago #7264
by nske
Replied by nske on topic Re: Recursive table lookup
It must be the procedure that a router follows to determine how to route packets with a specific destination (other than one in the subnets of it's itnerfaces).
i.e. a packet arrives at the router with destination address 10.14.142.20, the router has no interface to a subnet containing 10.14.142.20, so it first checks for an entry at the routing table refering to the appropriate subnet, i.e. 10.14.142.0/24. It may find an entry such as:
[code:1]
Destination Gateway Genmask Flags Metric Ref Use Iface
10.14.142.0 10.2.13.150 255.255.255.0 UG 0 0 0 eth4[/code:1]
So it will go back and check how it can contact 10.2.13.150. It will find an entry such as:
[code:1]
Destination Gateway Genmask Flags Metric Ref Use Iface
10.2.13.144 * 255.255.255.248 U 0 0 0 eth4
[/code:1]
So it knows it can contact 10.2.13.150 through the local interface eth4.
That's a simple example of recursion.
i.e. a packet arrives at the router with destination address 10.14.142.20, the router has no interface to a subnet containing 10.14.142.20, so it first checks for an entry at the routing table refering to the appropriate subnet, i.e. 10.14.142.0/24. It may find an entry such as:
[code:1]
Destination Gateway Genmask Flags Metric Ref Use Iface
10.14.142.0 10.2.13.150 255.255.255.0 UG 0 0 0 eth4[/code:1]
So it will go back and check how it can contact 10.2.13.150. It will find an entry such as:
[code:1]
Destination Gateway Genmask Flags Metric Ref Use Iface
10.2.13.144 * 255.255.255.248 U 0 0 0 eth4
[/code:1]
So it knows it can contact 10.2.13.150 through the local interface eth4.
That's a simple example of recursion.
19 years 10 months ago #7273
by Apostolis
Replied by Apostolis on topic Re: Recursive table lookup
nske, thank you for your explenation!!
Να 'σαι καλά,
Αποστόλης
Να 'σαι καλά,
Αποστόλης
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