Routing Tables :|

[DirtylilTechBoy]

How do they work???

 

[slackware1995]

<< How do they work??? >>



Basically, they compare the "destination" ip number of a packet with the routing table to determine where to send the packet.

For most people the big one is your "default gateway" route. What this does is send all packets with a destination ip number not already defined out through that interface for the next router to deal with.


Does this help or do you need more? Can you explain what you are specifically looking for?

 

[Talon]

Try the following site. It should help explain it.

routing tables

 

[DirtylilTechBoy]

What I have in mind is that a routing table is a two column table, with the first (left) column being the source IP and the second(right) column is the corresponding destination IP.

I assume each row would then represent where I wanted specific IPs or IP groups to be routed to.

I'm still want to learn the syntax though.

I need exposure to this stuff!

Thanks for the help!

 

[slackware1995]

<< What I have in mind is that a routing table is a two column table, with the first (left) column being the source IP and the second(right) column is the corresponding destination IP.

I assume each row would then represent where I wanted specific IPs or IP groups to be routed to.

I'm still want to learn the syntax though.

I need exposure to this stuff!

Thanks for the help! >>



Actually, basic routing tables do not take into consideration what the source ip number is, just the destination.

Hope that helps

 

[DirtylilTechBoy]

Ok, now I'm confused.

I always see two IP's in a router table row. What is the first one, and what is the second one?

 

[slackware1995]

show an example

 

[Nothinman]

You're probably referring to destination network address and gateway address.

 

[WarmAndSCSI]

Okay, in Windows, the routing table entries are setup like this:

Network Destination (the destination network number/subnet i.e. 192.168.0.0 (specifies what network this route is to forward to))

Netmask (the subnet mask of the destination network i.e. 255.255.255.0 (specified so the TCP/IP stack knows what the broadcast addresses are and the addresses of multiple subnets))

Gateway (the next "hop" to the destination network i.e. 192.168.1.1 (specifies the first router to forward packets that apply to this route to)

Interface (the interface on the computer/router that the packet will travel out of i.e. 192.168.2.1)

Metric (known as "Administrative Distance" in this case- specifies the trustworthiness of a connection; usually determined by delay, bandwidth, load, etc.)

So the format of an IP routing table entry is like this:

Desintation Network Subnet Mask Next Hop Outgoing Interface Metric/Administrative Distance
A.A.A.A 255.B.B.B C.C.C.C D.D.D.D E

So, basically... The routing system uses routing tables to determine the routes packets will travel along FROM itself when it receives packets from itself or other hosts. All of these routes can be manually entered - Static, dynamically aquired from other routers - Dynamic. The format for most routers for a static route is basically the same. On a Cisco router, you add a static route like this:

Router(config)# ip host A.A.A.A 255.B.B.B C.C.C.C Name of outgoing interface i.e. Ethernet 0 E

I hope that's a good enough explaination for ya