Routing Tables

C

CeD

Limp Gawd
Joined
Feb 10, 2003
Messages
182
Hi all,

Would anyone be willing to provide some pointers with routing tables? I have a network that I have to create routing tables for and I am lost. Any pointers would be greatly appreciated.

I have attached the network diagram:

network.gif


Any thoughts?
 
So you want us to do your homework for ya? Heh.

Do you need the routing tables for each ISP or just the biggest one?
 
No not at all asking you all to do my homework. That would not be right. I am just reading my book and not understanding what needs to be done for this situation. I am just asking for a few pointers to get me moving in the right direction.

A routing table for each ISP is required.
 
CeD said:
No not at all asking you all to do my homework. That would not be right. I am just reading my book and not understanding what needs to be done for this situation. I am just asking for a few pointers to get me moving in the right direction.

A routing table for each ISP is required.
Click to expand...

What book? Where did you get the diagram or did you make it yourself?

If you want "pointers" then your going to need to tell us what you don't understand or your level of knowledge thus far.
 
Hi SJConsultant,

Thank you for your help. As an example, the first question is:

Create the routing table for the regional ISP, providing the following:

Mask, network address, next-hop address, interface

I think that if someone could show me how the regional works, that I could figure out the remaining 5 questions.
 
Here is more info:

The first local ISP has divided its assigned subblock into 8 smaller blocks and assigned each to a small ISP. Each small ISP provides services to 128 households (H001 to H128), each using four addresses. Note that the mask for each small ISP is now /23 because the block is further divided into 8 blocks. Each household has a mask of /30, because a household has only 4 addresses (232−30 is 4).

The second local ISP has divided its block into 4 blocks and has assigned the addresses to 4 large organizations (LOrg01 to LOrg04). Note that each large organization has 1024 addresses and the mask is /22.

The third local ISP has divided its block into 16 blocks and assigned each block to a small organization (SOrg01 to SOrg15). Each small organization has 256 addresses and the mask is /24.

There is a sense of hierarchy in this configuration. All routers in the Internet send a packet with destination address 120.14.64.0 to 120.14.127.255 to the regional ISP. The regional ISP sends every packet with destination address 120.14.64.0 to 120.14.79.255 to Local ISP1. Local ISP1 sends every packet with destination address 120.14.64.0 to 120.14.64.3 to H001.
 
Give you a little tip to start, label all the interfaces for the routers.
 
next up the OP may want to consider working with the small ISPs first, since they have simpler routing tables (well somewhat).
 
Pretty big assignment using static routes. Here is a start.

Remember you need routing logic in both directions (so think about traffic going to and from!). After configuring this with static routes, you will really learn to love dynamic routing protocols.

From Household 001 to the internet

H001 has a directly connected network of 120.14.64.0/30 (4 subnets). Without additional routing entries, it will only know how to get to networks that exist in its routing table. In this case, as of now it only knows about 120.14.64.0/30. Since this is a stub network (only one way out), you can make use of a default route.

H001 routing table (using cisco logic, no serial interfaces have been given addresses or labels so it should be somewhat vague)

C 120.14.64.0/30 is directly connected
s 0.0.0.0/0 via SmallISP1's serial interface IP

0.0.0.0/0 is used to get to all other networks (it's a wildcard that matches everything not directly connected) because there is only one way out (through smallISP1)

Since Local ISP1 only has one way to the internet, it can also utilize default routing. Its routing table will look something like this. This is assuming those networks are not directly connected, so summarized static routes could be used. Remember routing finds its outgoing interface by finding the closest match to the destination IP address.

s 120.14.64.0/23 via SmallISP1's serial interface IP
s 120.14.66.0/23 via SmallISP2's serial interface IP
s 120.14.68.0/23 via SmallISP3's serial interface IP
s 120.14.70.0/23 via SmallISP4's serial interface IP
s 120.14.72.0/23 via SmallISP5's serial interface IP
s 120.14.74.0/23 via SmallISP6's serial interface IP
s 120.14.76.0/23 via SmallISP7's serial interface IP
s 120.14.78.0/23 via SmallISP8's serial interface IP
C 120.14.64.0/20 is directly connected
s 0.0.0.0/0 via RegionalISP serial interface IP

Regional ISP will look like this (thank goodness for summarization using CIDR right??):

s 120.14.64.0/20 via LocalISP1's serial interface IP
s 120.14.80.0/20 via ???? Unused at this time
s 120.14.96.0/20 via LocalISP2's serial interface IP
s 120.14.112.0/20 via LocalISP3's serial interface IP
s 0.0.0.0/0 via ??? Another Regional ISP's interface perhaps...

Hope this helps
 
Hi,

I am still having a tough time visualizing how that all fits into the table.

There are 4 columns:

Mask | Network Address | Next-hop Address | Interface
 
CeD said:
Mask | Network Address | Next-hop Address | Interface
Click to expand...

I'm sorry if this sounds overly rude but, have you ever read the book this diagram is coming out of? Have you looked up the basic definitions of the terms above?
 
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