Home lab troubleshooting

I thought I'd open a separate thread because I didn't want to derail the post your lab pics one with my own issues.

Here's my first problem I encountered:

I keep getting this CDP log message over and over on the crossover cable connection between two of my routers. What would cause a duplex mismatch issue like this between routers?

*Jun 1 22:22:33.344: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet0/1 (not full duplex), with R1 Ethernet0/1 (full duplex).

The Gigabit Ethernet side has auto duplex while the Ethernet has full duplex. Wouldn't the auto-negotiate mean that becomes full duplex too?

I suppose I could manually set the Gi0/1 interface to full duplex but I wanted to ask about it first. Can the problem be because one is Gigabit and the other regular Ethernet? Do I have to tweak the speeds? I thought it just goes as fast as the slowest type of connection when they are not the same on both sides of the link.

From what I've seen from a search, many others just choose to turn off the logging for this or turn off CDP (it usually pertains to connections to switches), but I'm interested in trying to fix it first or at least understanding why it may be happening.

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awitt11

Did you set the R1 Ethernet to Full or Auto? GE0/1 can't negotiate with a device that isn't negotiating. Leave them both Auto or set both Full.

the_dude7

Ah that's right, thanks, so the same kind of negotiating logic applies as to trunking and Etherchannel then?

As in having it "on" or nonegotiate on one end and negotiate the other will cause problems. Duplex settings don't have "desirable" modes, unlike trunking though.

EDIT- I set both to full and that made the link go down (as in the interfaces were up but line protocol was down). I then tried setting them both to half duplex and they went back up, and I can ping across them now.

Why would half work while full doesn't in this situation? Is it due to just being Ethernet and not Fast Ethernet?

Also when doing the sh int e0/1 command, the duplex settings don't even come up. While doing sh int gi0/1 on the other side of the link does display it.

the_dude7

New Question:

So I already got the cert but still want to play around with a home lab, and I got sidetracked for a while but I'm back. My question is about adding new cards/modules for extra Ethernet interfaces in your routers and why they're pretty expensive online.

a lot of the labs in the books I have and the lab example scenarios I find online have setups where three or more routers are directly connected to each other (presumably with crossover cables), and each also have switches connected to them, where the hosts and other devices behind them are in turn connected. I now have 3 routers and 3 switches. I wanted to connect them all in a kind of mesh topology but now I realize maybe that's not as easy as I thought. I want to at least have one in the middle connected to the other two, even if those aren't connected to each other. I have 2 crossover Ethernet cables and tons of regular straight through Ethernet cables.

Only problem is each of these routers only has two interfaces/ports for use (one of the routers has 2 Ethernet interfaces, another has 2 Fast Ethernet, and the last has 2 Gigabit Ethernet). Which means that one of each has to be used to connect to another router with a crossover while the other is to connect to its respective switch with the straight-through. But I can't have a direct connection to two routers at once and still have a connection to the switch. I thought it was as simple as going online and buying another interface card for another slot, to add ports. Only I realize they're all extremely expensive, often hundreds of dollars and more than the router itself; even the refurbished ones are around $100 at least.

Why are these so pricey??! In the sim labs it was normal to have lots of interfaces, so I guess I got used to the idea that it was easy to add and have lots of extra interfaces. Anyone know where to find good ones?

I guess other solutions to work around this are to have the switch in between the routers, although that's not exactly what I'm looking for. Or I could theoretically use a crossover serial cable (DB60) to connect the routers. I have one of those (DCE/DTE) but for some reason it's not working. Are those only meant to simulate "WAN" links?

Neil86

What routers are you using? Are you sure your not getting confused about connecting routers using serial links? I have six 1841's in my home lab that I interconnect using wic-2t cards and serial cables to simulate WAN links. The only devices connected to the Ethernet ports are my switches and it works great for my needs. I had to purchase the wic-2t cards and cables, but they can be relatively inexpensive on eBay. It sounds like that is what you want to do, but your equipment may not be equipped to do so? You can expand routers and add WIC cards, HWIC cards, etc... but verify your equipment supports what you are trying to do.

eBay HWIC-4ESW for $34.00 USD

https://www.ebay.com/itm/CISCO-HWIC-4ESW-4-Port-FE-EtherSwitch-Interface-Card-2800-3800-2900-3900-Router/262687381483?hash=item3d296357eb:g:NugAAOSwsB9WDaTx

HP_Guy

the_dude7 wrote: »

Or I could theoretically use a crossover serial cable (DB60) to connect the routers. I have one of those (DCE/DTE) but for some reason it's not working. Are those only meant to simulate "WAN" links?

Are you setting the clock speed on the interface at the DCE side?

clarson

yes router to router connection require cross over cables. straight cables are used to connect routers to switches

what you need to do is to segment one of your switches into vlans. each vlan is a separate network segment. a 24 port switch can be configured with 6 vlans with 4 ports each. tons of ways to connect those network segments into a network.

when your just learning it is easy to just deal with a switch instead of confusing the issue with creating network segments out of a switch and hoping you get it right. and besides hardware sellers would rather sell you 3 switches instead of one. And providing you customer service to get it right.

as far as a bad cable, a cable is hardware and doesn't go bad all that often. more than likely is it has been configured wrong. they are easy to configure wrong. I found it best to copy one that is already working. look on the internet for a good configuration. and they only simulate a wan link. in the real world you want your wan link to be longer than a few feet. but a few feet is all you need in a lab.

the_dude7

^Yeah that's what was confusing me. I have a super short serial cable that's a few inches long lol. Are these mostly just used in lab settings? I imagined that real WAN links often involved going across the publicly routed Internet through an ISP, NAT translations, etc. I guess in the lab examples they just cut that stuff out for simplicity's sake.

And yes I'm sure the cable itself is working fine, as it is brand new. It probably has something to do with the configuration. Maybe the clocking or duplex setting; I'll have to check. Also, which one do you pick as the DTE vs the DCE in a lab setting where you have several routers that are each meant to be equal, perhaps representing different offices? Is it just arbitrary in this case? I thought that distinction had to do with the connection between your own premises equipment like hosts on one end and the connection to the ISP on the other?

I guess you're right; I can segment the switches into VLANs too. That may complicate things for some labs though.

What routers are you using? Are you sure your not getting confused about connecting routers using serial links? I have six 1841's in my home lab that I interconnect using wic-2t cards and serial cables to simulate WAN links. The only devices connected to the Ethernet ports are my switches and it works great for my needs. I had to purchase the wic-2t cards and cables, but they can be relatively inexpensive on eBay. It sounds like that is what you want to do, but your equipment may not be equipped to do so? You can expand routers and add WIC cards, HWIC cards, etc... but verify your equipment supports what you are trying to do.

Ah, so you're saying people don't often use crossover Ethernet cables (RJ-45) to connect routers, but rather the serial (RS-232) type cables to do so? What are the differences practically and functionality wise? The serial creates a simulated "WAN type" connection in this case while the crossover Ethernet patch cables are meant for those in the same location or something? This was one thing they didn't really explain much in the testing books.

clarson

for the serial cable, the pin out for the dce and dte connectors are different. the connectors are marked to identify which is which. my cables have them marked dce and dte. and of course, the interface connected to the dce end of the cable has to configured as a dce device. and the dte end of the cable has to be connected to an interface that is configured as a dte device.

and if the configurations are correct but the cable is connected wrong, the ios will modify the configuration. so if you then connect the cable correctly, it still won't work. you get to start over configuring the interfaces.

the_dude7

Sigh, I don't get why I'm unable ping across the serial cable link. I have the clock rate set on the DCE side. But the DTE side says "clocks stopped". I just want to verify that at least the configuration is right. I also setup static routes across the serial link so I can ping test, and did a 'no shut' on both. Here's the relevant output:

here's R1, a Cisco 2800 series setting the clock rate

R1#sh ip int s0/0/0

Serial0/0/0 is up, line protocol is down
Internet address is 10.1.1.1/30
Broadcast address is 255.255.255.255
Address determined by setup command
MTU is 1500 bytes

R1# sh controllers int s0/0/0

Interface Serial0/0/0
Hardware is GT96K
DCE V.35, clock rate 64000
idb at 0x49886C58, driver data structure at 0x4988E230
wic_info 0x4988E85C
Physical Port 1, SCC Num 1

(this is the DCE side as labelled on the cable too)

---

here's R2, an old Cisco 2600 series router that's supposed to be receiving it

R2#sh ip int s0/0

Serial0/0 is down, line protocol is down
Internet address is 10.1.1.2/30
Broadcast address is 255.255.255.255
Address determined by setup command
MTU is 1500 bytes

R2# sh controllers int s0/0

Interface Serial0/0
Hardware is GT96K
DTE V.35 clocks stopped
idb at 0x81569F50, driver data structure at 0x81571CE4
SCC Registers:
General [GSMR]=0x2:0x00000000, Protocol-specific [PSMR]=0x8
Events [SCCE]=0x0000, Mask [SCCM]=0x0000, Status [SCCS]=0x00

There was a lot more output for the controllers for each but I cut it off. I also noticed though, that while in R1, it showed 'wic_info 0x4988E85C' as highlighted above, for R2, there was none of this... Could it indicate a bad wic card?

From searches I've done online on other forums, it may be that I got a faulty WIC-1T card... or at least that I installed it poorly. Is that a possibility? Cisco there's there's a "grey" market out there that often has sub-standard equipment. I think I got this on Amazon.

Neil86

How about more info:

- complete running-configs of routers
- full show controllers output

you could put those in separate text files and upload them to save thread space.

Have you tried reversing the cable and having the clock signal coming from the other device? How about swapping the wic cards between devices to see if the issue moves with the card?

Did you reset these routers to factory defaults when you acquired them?

clarson

try something like this

https://confterminal.com/configuring-serial-interfaces/

and there are lots of other webpages about how to interface wan cards

the_dude7

Neil86 wrote: »

How about more info:- complete running-configs of routers- full show controllers outputyou could put those in separate text files and upload them to save thread space.Have you tried reversing the cable and having the clock signal coming from the other device? How about swapping the wic cards between devices to see if the issue moves with the card?Did you reset these routers to factory defaults when you acquired them?

Indeed I reversed the cables and tried having the clock signal come from the other device; it didn't change anything. Then I took out the WIC card that I thought might be problematic from R2 and put it in the third router I have (a newer 1841, called R3), also partly since I thought the problem might also have been with the really old R2 router from 2005 or whatever, which I noticed has a lot of features missing since it's running an older IOS (version 12 I think) and has a very low amount of space on it to begin with and can't be upgraded to a newer version.

One difference I noticed in the configs this time was that, unlike last time, when one of the hardware was listed as PowerQUICC, this time both serials came up as GT96K.A more notable change was that (after setting up the serial links on both sides and connecting them, and turning on the interfaces), I keep getting the line protocol on R1 (which is setting the clock speed, in this case 64000 Kb/s), changing from up to down every few seconds. On R3, with the WIC card I transferred, it is simply in a down/down state.

here's a sample of that:

R1#*Sep 19 21:00:13.850: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/ 0, changed state to downR1#*Sep 19 21:00:16.258: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/ 0, changed state to upR1#*Sep 19 21:00:43.854: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/ 0, changed state to downR1#*Sep 19 21:00:46.258: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/ 0, changed state to up

this goes on and on...

And yes, earlier this week I completely wiped the configurations of all my devices to start anew.

I'll attach some text files of the output you mentioned. The full output of the show controllers is extremely long, especially for R1... I'm not sure what all that stuff toward the end is. Also wasn't sure if you wanted me to do just a show controllers for the specific serial interface or for all ints, so I just did all. You might need to dig thru the text a bit to see the relevant part with Serial 0/0/0.

I noticed in the running config for R3, unlike R1, there's a line that says

! card type command needed for slot/vwic-slot 0/1

Not sure if that has to do with the problem or not.

EDIT- for some reason a .txt file was an invalid option to upload here so I had to go with .doc.

serial connection troubleshoot.doc