Config problem

[jamin123]

What am I doing wrong? I want to upgrade IOS on RouterA.
RouterA and RouterB are back to back. I can ping all interface except I can't ping from RouterA to the TFTP.
RouterA doesn't have an E0 so I need an easy way to upgrade IOS.
RouterA
interface Serial0
ip address 172.16.20.2 255.255.255.0
!
router igrp 10
network 172.16.0.0

RouterA#sh ip route
172.16.0.0/24 is subnetted, 2 subnets
C 172.16.20.0 is directly connected, Serial0
I 172.16.10.0 [100/8576] via 172.16.20.1, 00:00:08, Serial0

RouterB
interface Ethernet0
ip address 172.16.10.2 255.255.255.0
no mop enabled
!
interface Serial0
bandwidth 1544
ip address 172.16.20.1 255.255.255.0
!
router igrp 10
network 172.16.0.0

RouterB#sh ip route

172.16.0.0/24 is subnetted, 2 subnets
C 172.16.20.0 is directly connected, Serial0
C 172.16.10.0 is directly connected, Ethernet0


TFTP (WIN 2K)
172.16.10.1 255.255.255.0

 

[wybnormal]

First, TFTP requires either UDP forwarding or IP helper enabled to pass between subnets. Broadcast domains stop at the subnet boundry so you need a way to get beyond that.

See this link for a fun explantion

http://www.routergod.com/trinity/

Dump the IGRP and put static routes in place to make your life simple. You have a classful protocol with classless masks.. in other words, IGRP is classful. It does not send subnet info with the routing update. But, you are using a Class C mask with a Class B address. That mask is not being sent.

!
interface Serial0
ip address 172.16.20.2 (255.255.255.0) <--error
!


Possible design...

routera------------------routerb-------------TFTP server
172.17.20.2 172.17.20.1 172.16.10.2 172.16.10.1

IP helper enables ten broadcast protocols across the subnet boundry and TFTP is one of the ten.

MikeS
Find me at

http://www.packetattack.com

&quot;The trouble with giving up civil rights is that you never get them back&quot;

 

[jamin123]

Still cannot ping TFTP from RouterA. This is my home lab. I am at work and typing the below config from memory.

routera------------------routerb-------------TFTP server
172.17.20.2 172.17.20.1 172.16.10.2 172.16.10.1



RouterA
interface Serial0
ip address 172.16.20.2 255.255.0.0
!
ip route network 172.16.0.0 255.255.255.0 172.17.20.1
!


RouterB
interface Ethernet0
ip address 172.16.10.2 255.255.0.0
ip helper-address 172.16.10.1
!
interface Serial0
ip address 172.16.20.1 255.255.0.0


!
ip route network 172.17.20.0 255.255.255.0 172.17.20.1 ?

!
ip forward-protocol udp

TFTP (WIN 2K)
172.16.10.1 255.255.0.0

 

[jamin123]

Still cannot ping TFTP from RouterA. This is my home lab. I am at work and typing the below config from memory.

routera------------------routerb-------------TFTP server
172.17.20.2 172.17.20.1 172.16.10.2 172.16.10.1



RouterA
interface Serial0
ip address 172.16.20.2 255.255.0.0
!
ip route network 172.16.0.0 255.255.255.0 172.17.20.1
!


RouterB
interface Ethernet0
ip address 172.16.10.2 255.255.0.0
ip helper-address 172.16.10.1
!
interface Serial0
ip address 172.16.20.1 255.255.0.0


!
ip route network 172.17.20.0 255.255.255.0 172.17.20.1 ?

!
ip forward-protocol udp

TFTP (WIN 2K)
172.16.10.1 255.255.0.0

 

[wybnormal]

On your serial links.. I do not see the DCE set for clocking...ie.. clock rate XXXX

If you do a show interface sx, do you see the interface as up and up? refering to interface and protocol?

Here is a sample of the simplest back to back, HDLC

http://www.cisco.com/warp/public/116/hdlc_back.html

Here is a link for Frame Relay back to back, not that need to use frame, it does make for nice practice.

http://www.cisco.com/warp/public/125/frbacktoback.html

back to back PPP

http://www.cisco.com/warp/public/116/ppp_back.html

MikeS
Find me at

http://www.packetattack.com

&quot;The trouble with giving up civil rights is that you never get them back&quot;

 

[jamin123]

The infaces are up and running and I can ping to and from all interface execpt I cannot ping from RouterA to TFTP.
This critical in order to upgrade RouterA IOS.

Maybe what I am tring is not possible.

 

[svermill]

jamin123,

Since you are typing your config from memory, I'm not sure it's worth going through all of the problems. You may want to post actual cut-and-paste configs. Suffice to say that, since you have the entire 172.16.0.0 network on your serial connectivity and also behind routerb at e0, you've got some problems.

When you've got all that worked out, make sure that your tftp server has its gateway set correctly ('ipconfig' from a dos prompt). You should be able to at least ping the machine regardless of any udp forwarding issues. Conversely, you should be able to ping the target router from the tftp server. You can use traceroute to find out where things are breaking down if necessary.

Finally, don't forget that routerb can be set up as a tftp server if it already has the upgrade you are wanting for rotuera.

MikeS,

I think the original IGRP config was fine. Remember that Cisco routers assume that whatever subnet is used on directly attached interfaces is used throughout the network (when dealing with classless protocols of course). In this case, 255.255.255.0 was used consistently. Notice that the routing tables are good. Also, I'm not sure that udp forwarding is an issue is it? In this case, no workstation on a shared subnet is broadcasting out for a TFTP server. The specific address of the server is specified as part of the 'copy tftp flash' process.

Regards,

Scott

 

[svermill]

As a follow up, I was able to tftp files across this exact topology without any helper or udp forward config. The key is that this is unicast and not broadcast.

 

[wybnormal]

I know it's possible.. I've done it to upgrade a 2504 (TokenRing and serial) via the serial.

Scott has a very good point in posting the exact configs so we do not keep chasing our collective tails thinking something is missing but it's really not missing. I'm it will be something very straightforward to see once all the data is presented.


MikeS Find me at

http://www.packetattack.com

&quot;The trouble with giving up civil rights is that you never get them back&quot;

 

[CCIEWANNABE]

I cannot ping from RouterA to TFTP seams to be your current issue correct?

Also you state: I think the original IGRP config was fine?

Verufy IGRP is Enabled? It must be enabled on the interfaces in question
Is this a Discontiguous subnet? Post a Debug IGRP Transaction for all routes in question.

You seam to have the correct network statements yet in oe of your last posts the mask values are incorrect.
SInce this is a home lab why not use RIP version 2 in supports Discontiguous subnets!

Route once; switch many

 

[jamin123]

MikeS,
RouterB has the latest IOS so how do I set it up as a TFTP server? Please, may I have a link or config?

&quot;Finally, don't forget that routerb can be set up as a tftp server if it already has the upgrade you are wanting for rotuera.&quot;


Thanks.

 

[svermill]

jamin123,

You issue:

router(config)#tftp-server flash:filename

on routerb.

Then just do the 'copy tftp flash' as you normally would from routera.

I still think if you get to a point where you can ping the machine you will be home free. Again, check the default gateway on the tftp server and then do traceroute if that doesn't fix it.

CCIEWANNABE,

That was me that said the IGRP config was fine. My point was that the 255.255.255.0 mask was used consistently throughout the network so the classful nature of IGRP didn't present any real problem. Indeed, the routing table of routera had the subnet on which the tftp server resides and it got it via IGRP (see some of the early postings).

 

[jamin123]

Thanks to every1. Problem was the default gateway.

http://www.cisco.com/warp/public/63/install_tftp.html#before_reloading

 

[svermill]

jamin123,

Was it the default gateway of the router or the tftp server that was the problem? A default gateway for a router is only necessary if there is no routing protocol and no static routes configured.

Thanks for writing back to let us know how it finally worked out. Lots of folks never bother and a learning opportunity is lost for everyone who invested their time to help out or follow along.

Regards,

Scott

 

[jamin123]

The default gateway of the tftp server