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RE: linux netconf problem and /28 & /27 ip route setup



Hi Paul.
 
ISL and 802.1Q Trunking is a method of tagging VLAN information with user-defined IDs. This ensures that when VLANs are crossing switches, the VLAN information is maintained. This is so that you reduce on the involvement of a layer 3 device/router in switching packets. VLAN information is routed using an internal route processor, such as an RSM or MSFC card.
 
However, even an external router processor [a router typically] can do the same. The idea here is not having to go through a router when you want to route between separate VLANs, because each VLAN represents a physically separate switch, the same way it used be done in the days of the hub. For your setup, you may not need this now, but it would be a good idea to plan this for the future, as you scale your routing protocol configuration.
 
How many routers do you have? Do you have a core and distribution router, or do you have on router that connects to the Internet, and also provides access to services? If the latter, simply plug the ethernet interface into the switch, subnet your first /28 onto that ethernet interface, and you have your subnet. You can then assign IPs within that subnet to your servers, including your Linux gateway. Ensure you assign their gateway as the IP you setup on your router. Your router config would be something like this:
 
conf t
 int fa0/0
  ip address 64.110.88.1 255.255.255.240
 
Fa0/0 is if your ethernet interfaces are fast ethernet [10/100Mbps], otherwise it should be e0/0 [10Mbps]. That basically subnets 64.110.88.0/28 on your network.
 
So, assign your Linux 64.110.88.2, then your mail 64.110.88.3, then your DNS 64.110.88.4 and so on and so forth. Remember, the default gateway for all these devices is the router, 64.110.88.1.
 
Once you have exhausted all 14 IPs, you can then subnet your next network, and continue in the same manner. If you provide synchronous services, such as frame relay or leased line, the configuration gets slightly different, but the concept is the same.But, baby steps first.
 
You have a sufficient number of fast ethernet switches, but work with one for now. Don't try to connect all 3 together for now, you could have some STP [Spanning Tree Protocol] issues if they aren't properly configured. This could make your situation a little trickier.
 
I urge, start simple, and build your way up. Having 3 NICs in your Linux gateway is a very good idea, but may complicate your firewall configuration for now. Start with two, then move on from there.
 
Regards,

Mark Tinka - CCNA
Network Engineer
Africa Online Uganda
5th Floor, Commercial Plaza
7 Kampala Rd,
Tel:   +256-41-258143
Fax:   +256-41-258144
E-mail: mtinka at africaonline.co.ug
Web:     www.africaonline.co.ug
 

-----Original Message-----
From: Paul [mailto:pademmy at yahoo.com]
Sent: Saturday, March 15, 2003 10:04 PM
To: mtinka at africaonline.co.ug
Subject: RE: linux netconf problem and /28 & /27 ip route setup

Hi Mark,

thanks for your mail I really appreciate. pls if I may ask what is ISL [Inter-Switch Link] or 802.1Q VLAN trunking?.

And secondly on the ip route setup on my router for /28 was setup like this 64.110.0.0 255.255.255.240 64.110.88.68 becos 68 is my linux box gateway, becos what I try to do is to put my network behinde the router and my router ethernet interface is 65 first host on /26 followed by my bcu and skystream dvb system.

I have cisco switch 2950 series on my network, one for my in house network, second for my management network and the third for my distribution to the client for point to multipoint and point to point client.

but now the three systems are seeing each other that's the mail server on /28 subnet and dns and apache on /28 subnet too with the linux gateway router on /26 subnet but the in house is not working becos I have a NAT implemented on my router and the linux gateway has three NIC with /28 subnet, /26 subnet and /24 subnet of private ip address for my in house network, and my inhouse is not working yet.

pls can you use your expert and exposure experience to figured out for me where the problem is on my network, becos I have given you the breakdown of my network now.

thanks.

ajayi.



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