Routing Vlans (subnets) on 3550

[summerdike]

When routing is turned on, on network 172.16.0.0 is it also turned on on subnetworks of 172.16.0.0?

The below configuration is NOT changed with the addition of these lines. The commands are accepted but printout remains the same:

configure terminal
router rip
network 172.16.23.0

Printout of the routing settings:
_______________________________________________
demoswitch1#show ip protocols
Routing Protocol is "rip"
Sending updates every 30 seconds, next due in 16 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Redistributing: rip
Default version control: send version 1, receive any version
Interface Send Recv Triggered RIP Key-chain
Vlan1 1 1 2
Vlan23 1 1 2
Automatic network summarization is in effect
Maximum path: 4
Routing for Networks:
172.16.0.0
172.30.0.0
172.32.0.0
192.168.1.0
Routing Information Sources:
Gateway Distance Last Update
Distance: (default is 120)


______________________________
"Reload and Restart Requested
System Initiated"

 

[ADB100]

RIP is a classful routing protocol so 'knows' what mask any address should have. For example the correct mask for IP address 172.16.23.1 is 255.255.0.0, NOT 255.255.255.0. As you can see in your RIP configuration only the classful network statements will exist. RIP also 'assumes' all subnets of any major network share the same mask, it doesn't support VLSM. For example if you had an interface with ip address 172.16.1.0/24 any other subnets from 172.16.0.0/16 MUST have /24 subnet masks.
RIP V2 has the concept of subnet masks and sends the prefix with its updates, it will be default summarise networks at boundaries - i.e. a router with 2 interfaces E0 10.1.1.1/24 and E1 192.168.1.1/24. Out of the E0 interface an update for network 192.168.1.0/24 will be sent, whilst out of the E1 interface 10.0.0.0/8 will be sent. This behaviour can be disabled with RIP V2 by configuring 'no auto-summary'

HTH

Andy

 

[summerdike]

As I understand you correctly, network 172.16.23.0 is NOT communicated by Cisco 3550 with RIP version 1?


______________________________
"Reload and Restart Requested
System Initiated"

 

[ADB100]

I am not sure what you mean by '172.16.23.0 is NOT communicated'?

With RIP V1 any network statements you add will revert to the correct classful address: i.e. if you enter the following:

router rip
network 10.1.1.0
network 172.16.10.0
network 192.168.10.0

it will appear in the config as

router rip
network 10.0.0.0
network 172.16.0.0
network 192.168.10.0


And RIP will run on all interfaces that the network statements cover - if you have 2 interfaces:

interface Ethernet0
ip address 172.16.10.1 255.255.255.0
!
interface Ethernet1
ip address 172.16.20.1 255.255.255.0


RIP will run on both interfaces and because both masks are the same will work OK.

HTH

ANdy

 

[Jsteve]

what you need to add on all your routers/L3 switch

router rip
version 2
np auto-summary

 

[summerdike]

I mean the network 172.16.32.0 is not dynamically updated through the network.
I had to add a static route to a router that is running Windows2000 (RIP version 2a).
Default gateway of a part of the network is 172.16.2.1/24
Vlan1 routing interface on Catalyst3550 is 172.16.2./24. Vlan23 on Catalyst3550 has default gateway 172.16.23.1/24 on subnet 172.16.23.0.
I had to add a static route to router with interface 172.16.2.1.

Why is his routing table not dynamically updated by the Catalyst3550, telling "him" where to send packets for 172.16.23.0/24?


______________________________
"Reload and Restart Requested
System Initiated"

 

[ADB100]

Its all a bit out there this conversation...

Can you post the config or the relevent bits. I am not sure what you are saying when you say the 'default gateway of part of the network..' Where are you adding static routes? on hosts or on the 3550?

Andy

 

[summerdike]

Here's a picture of the configuration.

I had to add static routes to the windows2000 server in the picture in order to be able to succesfully ping from hosts on Vlan21 to Vlan24 to the Windows2000server/domain controller.


______________________________
"Reload and Restart Requested
System Initiated"

 

[ADB100]

Right I think I see the problem. Your Windows 2000 Server has 2 connections (?) one to the Catalyst 3550 and another probably to the Internet? (I am assuming this by the 'Router' comment below it in the diagram). If this is the case then what you are seeing is correct.
Without a routing protocol running on the Windows 2000 Server you need to tell it which interface (and gateway) to use for different IP routes. If you have only a single NIC then it's easy as all your off-net traffic must go via the same gateway.
I have a very similar setup to you and instead of adding lots of routes on the Windows 2000 Server I have a single route allowing me to use all the 172.16.0.0/16 address space internally:

route add 172.16.0.0 mask 255.255.0.0 172.16.2.1

I just re-read the previous posts and would like to add:
I am not too sure about the RIP implementation on Windows but bear in mind it could be either Broadcast or Multicast (officially it is Multicast but I have seen vendors implement Broadcast). I don'g know how a Windows server would interpret the updates neither as they will NOT be classfull? I think you can look at the routing table in the Routing & Remote Access MMC, what does this show you?

HTH

Andy

 

[summerdike]

This is routing table on windows 2000 server:
highlighted are the static routes added.

______________________________
"Reload and Restart Requested
System Initiated"

 

[ADB100]

I think you need to get a sniffer on the VLAN 1 and make sure you are seeing the updates from the Cisco switch (I would assume you are based on the config). You then need to look at the RIP configuration on the Windows Server and see why it isn't accepting the updates?

I will try and configure this later, although I may need to build a 2000 Server first.

Andy