topic sorry - lost my connection to in Switching

1841 - I can ping and tracert but not browse

patrsup — Fri, 08 Mar 2019 10:42:03 GMT

I am still working on the switching and routing at a small school. I have the 1841 hanging off port 48 on my 3750 switch and it connects to the router in port 1.

I am trying to get this 1841 to host several ubiquity access points and provide basic dhcp services. The 3750 is doing well with its setup I believe.

I have included the three configs i have.

Thanks in advance for your time

pat

So is the connectivity -

Jon Marshall — Fri, 13 Nov 2015 22:12:20 GMT

Edit, can you just draw a quick diagram to show what you are trying to do.

Jon

here is a quick sketch - Im

patrsup — Sat, 14 Nov 2015 00:04:03 GMT

here is a quick sketch - Im on the road so it was done in a burger joint - sorry for the quality

Thanks for the diagram.

Jon Marshall — Sat, 14 Nov 2015 00:23:35 GMT

Thanks for the diagram.

So on your 1841 you have a default route pointing out fa0 interface which has a 192.168.1.5 IP.

But both the 3750 and the 1900 router have an IP from this range as well.

In additon the 3750 is routing for another vlan ie. 53.

You are also doing NAT on the 1841 translating the 172.23.1.x IPs to 192.168.15 but then doing NAT on the 192.168.1.x IPs on the 1900.

So it is all a bit confused because you have extended one IP subnet between everything whilst at the same time you are routing different subnets on the 1841 and 3750.

I am still not sure why you need the 1841 unless you have run out of ports on the 3750 ie. why not just connect the APs to the 3750 as it is already routing anyway ?

Even if you keep the 1841 I can't see the point of doing NAT on that router.

Can you perhaps explain the reasoning behind it.

I'm not saying it is wrong but it might help me to provide a better answer to your question.

Jon

Jon,

patrsup — Sat, 14 Nov 2015 03:08:04 GMT

Jon,

Thanks for the questions, it illuminates my lack of knowledge on the lan setups - Here is what I need at a minimum

The 1900 for the connecton to charter. All it's supposed to do is provide the inside to the outside routing.

The 3750 is supposed to be a distribution switch and feeds several other smaller linksys routers supporting the back office and one in each of two computer labs. Additionally, it connects through a barracuda to 4 OLD cisco business switches which are unmanaged and really are acting as hubs.

I have two more 1900 series switches and 4 more 3750's which I could use to get the traffic off the old business switches and add seprate subnets for the wireless and the teachers computers which are on wired lan connections but I am not sure how to set them up at this point..

I have the entire school running off the 1900 and and the 3750 distribution switch. The wireless is currently hanging off it by 100 mp rj45 connections to two linksys routers supporting two school wide wireless networks on ubiquity accesspoints. I have to reboot these linksys routers about every 4 hours as they overheat and will not give out dhcp addresses nor route traffic.

The 1841 is an effort to replace these two linksys routers with one device and subnet.

I would like to have a setup with 5 individual subnets each /24 and the appropriate routing between the 3750's but that is outside my knowledge base at this point.

Hope this helps clear up what I have going on

pat

Hello,

Masoud Pourshabanian — Sat, 14 Nov 2015 05:02:32 GMT

Hello,

Are you able to ping 192.168.1.1 from 1841?

***********

on 1841 configure these commands.

ip route 0.0.0.0 0.0.0.0 192.168.1.1

no ip route 0.0.0.0 0.0.0.0 FastEthernet0

no ip route 172.23.1.0 255.255.255.0 FastEthernet0

interface FastEthernet0

no ip nat outside

****************************************

on 1900

interface GigabitEthernet0/1

no ip access-group incoming in

*************************]

Please share the result.

Masoud

Thanks for clarifying.

Jon Marshall — Sat, 14 Nov 2015 13:39:28 GMT

Thanks for clarifying.

I appreciate your initial post was about troubleshooting so I don't want to go off and redesign your network but I really don't think you need the 1841.

You could just use your existing 3750 and create a new vlan if you want for the APs.

You could then do all your routing between vlans on the 3750 and only send traffic to the 1900 for remote subnets.

Your 3750 will support routing between multiple vlans.

This would make your setup a lot simpler to manage as you go forward.

You could if you needed use one of your other 3750s as a L2 switch only for the AP connections and then simply connect to the L3 3750 you are currently using for the routing.

We can help you set all of that up although actually just to migrate the APs to the 3750 would be relatively trivial but if you also wanted to use more vlans/IP subnets we could help with that too.

Like I say though if you just want to troubleshoot what you have then we can help as well.

I still don't see a need to do NAT on the 1841 though.

Let us know what you want to do.

Jon

Jon,

patrsup — Sat, 14 Nov 2015 17:45:37 GMT

Jon,

Sounds like a lot of work for you but if you wanted to do the configs for the 1900 and two 3750's with 4 subnets (two each on the 3750's) I would be glad to toss the 1841. I need one of the subnets to remain 172.24.53.0 due to static ip's throughout the network but other than that they can be anything.

Thanks again

Pat

Jon Marshall — Mon, 16 Nov 2015 10:35:51 GMT

Pat

I was thinking of routing all the subnets on your existing 3750.

So you would replace the 1841 with one of your 3750s and then connect that to the existing 3750 with a trunk link.

You can connect your APs to the new 3750 and then create the L3 vlan interfaces on the 3750.

The subnets can use any addressing you want.

Does this sound okay ?

Jon

That would be fine -

patrsup — Mon, 16 Nov 2015 12:30:36 GMT

That would be fine -

Again, I think you for your help with this

Sorry one last question.

Jon Marshall — Mon, 16 Nov 2015 13:08:11 GMT

Sorry one last question.

Are the 3750s you mentioned currently in use or is it a spare ?

If it is in use how it is connected currently ie. to what ?

And can you post a "sh vtp status" from your existing 3750.

I just want to make sure we don't mess up the vlan database on your existing switch.

If you confirm the above I can give you the steps you need to set it up.

I won't be around until later but I should be able to post this evening (UK time).

Let me know.

Jon

I have two spare 1941's and

patrsup — Mon, 16 Nov 2015 13:13:47 GMT

I have two spare 1941's and three spare 3750's so you can just make the configs how you want and I will put them on the spare equipment and then cutover when complete

Thanks again

Pat

Do you know if the APs need

Jon Marshall — Mon, 16 Nov 2015 17:55:07 GMT

Do you know if the APs need trunk connections or not ?

And can you post "sh vtp status" from your existing 3750.

Jon

XWALGOMA-Entrance#sho vtp

patrsup — Mon, 16 Nov 2015 18:06:39 GMT

XWALGOMA-Entrance#sho vtp status
VTP Version capable : 1 to 3
VTP version running : 1
VTP Domain Name : Algoma2
VTP Pruning Mode : Disabled
VTP Traps Generation : Disabled
Device ID : 0022.0d09.3c80
Configuration last modified by 0.0.0.0 at 0-0-00 00:00:00

Feature VLAN:
--------------
VTP Operating Mode : Transparent
Maximum VLANs supported locally : 1005
Number of existing VLANs : 9
Configuration Revision : 0
MD5 digest : 0xEC 0x1B 0xF6 0x60 0xAF 0x82 0x10 0x79
0xF9 0xCC 0x9D 0x16 0xED 0xE3 0x97 0xC9
XWALGOMA-Entrance#

Are you going to be doing

Jon Marshall — Mon, 16 Nov 2015 18:23:40 GMT

Are you going to be doing this as we go along or in one big hit ?

And can you have any downtime ?

There are a couple of changes needed that may have a slight affect on the network ie a temporary outage of about 50 seconds no more.

If you want we can do it step by step as I am online for a while as you need to make changes to the existing 3750 (nothing major) and to the 1900 router (again nothing major).

Jon

I was going to put the

patrsup — Mon, 16 Nov 2015 18:32:50 GMT

I was going to put the configs on the spare 1900 and two 3750's. stage in the rack and cutover sometime after 3:30pm est when the students and faculty are gone.

Okay, so I am 5 hours ahead

Jon Marshall — Mon, 16 Nov 2015 18:37:54 GMT

Okay, so I am 5 hours ahead of you.

What do you mean by the spare 1900 ie. we are only going to replace the 1841 with a spare 3750 or are you thinking of something else as well ?

Do you want to wait until after they have gone ?

Basically you can get your spare 3750 ready now and I can give you the commands but the rest is on your existing equipment.

Jon

That is fine, I had a spare

patrsup — Mon, 16 Nov 2015 18:41:26 GMT

That is fine, I had a spare 1941 an several 3750's and was going to put the configs on them and bring them up and just move them into production after the kids were gone but I can work on the existing stuff if you can let me know what I have to do

thanks again

So on your spare 3750, power

Jon Marshall — Mon, 16 Nov 2015 18:55:08 GMT

So on your spare 3750, power it up but don't connect it to your distribution switch yet.

Then on the spare 3750 -

switch(config)# vtp mode transparent

then pick a new unused vlan number ie. it must not be used on your existing 3750.

This vlan will be for the APs.

switch(config)# vlan <num>
switch(config)# name <whatever you want>

and if you do a "sh vlan brief" you should see it.

Couple of things -

1) do you know if the APs need to have trunk connections ie. pass more than one vlan or do they just need to be in one vlan ?

2) once I know the above you can configure the ports on the spare 3750 that the APs connect to.

Then you have to connect your spare 3750 to the existing one.

Before you do that though you need to create the same vlan on your existing 3750 using the same commands as above and we need to set your existing 3750 to be the STP root for alll vlans

This is the bit that may affect the network temporarily so up to you whether we connect them now or wait.

Can you confirm the above.

Jon

no trunk connection required

patrsup — Mon, 16 Nov 2015 19:14:20 GMT

no trunk connection required - they can be in the same vlan -

This is what I have on the spare currently

I did a wri e so there is nothing else on the switch