topic Cisco 2951 router issues in Routing and SD-WAN

Cisco 2951 router issues

roncro — Thu, 26 Oct 2023 07:02:13 GMT

Hello, I have a Cisco 2951 router I use at home, and I suspect it to give me some issues.

The internet (via a cisco cable modem) drops the conenction (status says there is no traffic) and the connection drops

I checked the router and I see log messages saying:

Oct 12 01:09:41.068: %IP_VFR-3-COALESCE_ERROR: Unable to coalesce fragments arriving through GigabitEthernet0/0 - datagram 4121 bytes is too big. UDP packet 75.75.75.75:53 -> A.B.C.D:59499 has ident: 50999 flags:0x0 and 3 fragments

At first I thought it was the modem, or the cable connection, but now I am not sure. The problem seems to be intermittent and comes in "waves".

(The 75.75.75.75 is a comcast dns server)

Also, when the internet connection drops, the router seems to become unresponsive (can't ping it, if logged it it drops the session)

any ideas?

Thanks,

Ron

Re: Cisco 2951 router issues

roncro — Thu, 26 Oct 2023 09:40:44 GMT

Also once the connection is up, when I ping google.com the

icmp

responses I get come from youtube-ui.l.google.com .. and when I do a traceroute to something (like a dns server) I seeem to get different routes, with different response times

Re: Cisco 2951 router issues

Elliot Dierksen — Thu, 12 Oct 2023 11:44:55 GMT

I found some references to bugs that could generate this error. Is the router directly on the internet with a public IP address? If so, it could be getting attacked. If it is behind a firewall then the bug scenario sounds more likely.

Re: Cisco 2951 router issues

balaji.bandi — Thu, 26 Oct 2023 09:43:59 GMT

Can you post show version and show interface

GigabitEthernet0/0

Re: Cisco 2951 router issues

roncro — Thu, 12 Oct 2023 15:54:21 GMT

Yes it is connected to the internet via a modem, but from the outside only an ssh port is open, and is directly forwarded to a linux machine. (which has a firewall)

Re: Cisco 2951 router issues

roncro — Thu, 26 Oct 2023 09:44:49 GMT

Here it is,

it looks like it just restarted ...

here is the info, thanks!

Charon-2951 uptime is 16 minutes
System returned to ROM by address error at PC 0x4AC7AD4, address 0x4AC7AD4 at 09:36:57 MDT Thu Oct 12 2023
System restarted at 09:38:53 MDT Thu Oct 12 2023
System image file is "flash0:c2951-universalk9-mz.SPA.151-4.M4.bin"
Last reload type: Normal Reload


This product contains cryptographic features and is subject to United
States and local country laws governing import, export, transfer and
use. Delivery of Cisco cryptographic products does not imply
third-party authority to import, export, distribute or use encryption.
Importers, exporters, distributors and users are responsible for
compliance with U.S. and local country laws. By using this product you
agree to comply with applicable laws and regulations. If you are unable
to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:
http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

If you require further assistance please contact us by sending email to
export@cisco.com.

Cisco CISCO2951/K9 (revision 1.1) with 483328K/40960K bytes of memory.
Processor board ID FCZ1622702R
3 Gigabit Ethernet interfaces
1 terminal line
DRAM configuration is 72 bits wide with parity enabled.
255K bytes of non-volatile configuration memory.
250880K bytes of ATA System CompactFlash 0 (Read/Write)


License Info:

License UDI:

-------------------------------------------------
Device# PID SN
-------------------------------------------------
*0 CISCO2951/K9 FCZ1622702R




Technology Package License Information for Module:'c2951'

-----------------------------------------------------------------
Technology Technology-package Technology-package
Current Type Next reboot
------------------------------------------------------------------
ipbase ipbasek9 Permanent ipbasek9
security None None None
uc uck9 Permanent uck9
data None None None

Configuration register is 0x2102


Charon-2951#show interface GigabitEthernet0/0
GigabitEthernet0/0 is up, line protocol is up
Hardware is PQ3_TSEC, address is a44c.11d4.afc0 (bia a44c.11d4.afc0)
Description: WAN
Internet address is 69.254.c.d/23
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full Duplex, 1Gbps, media type is RJ45
output flow-control is unsupported, input flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/185/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 1371000 bits/sec, 158 packets/sec
5 minute output rate 72000 bits/sec, 56 packets/sec
464814 packets input, 458030740 bytes, 0 no buffer
Received 5 broadcasts (0 IP multicasts)
0 runts, 0 giants, 3 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
189244 packets output, 26921538 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out

Re: Cisco 2951 router issues

paul driver — Thu, 12 Oct 2023 17:27:33 GMT

Hello
Possible bug <here> try upgrading software.

Re: Cisco 2951 router issues

roncro — Fri, 27 Oct 2023 12:02:36 GMT

Thanks Paul,

I checked and saw, this below. Is there an "ideal" size to try? (without messing too much up?)

(I did actually see some " Unable to coalesce fragments.." errors yesterday, but don't see them now any more. They appeared to be generated by a

comcast/xfinity dns server

)

thanks,

Ron

Charon-2951(config)#buffers huge size ?
<18024-65535> Size of huge buffers

Charon-2951#show buffers
Buffer elements:
592 in free list (500 max allowed)
55988 hits, 0 misses, 617 created

Public buffer pools:
Small buffers, 104 bytes (total 80, permanent 50, peak 80 @ 00:28:35):
77 in free list (20 min, 150 max allowed)
18326 hits, 10 misses, 0 trims, 30 created
0 failures (0 no memory)
Middle buffers, 600 bytes (total 58, permanent 25, peak 58 @ 00:28:35):
56 in free list (10 min, 150 max allowed)
10816 hits, 11 misses, 0 trims, 33 created
0 failures (0 no memory)
Big buffers, 1536 bytes (total 51, permanent 50, peak 51 @ 00:29:22):
51 in free list (5 min, 150 max allowed)
27026 hits, 0 misses, 0 trims, 1 created
0 failures (0 no memory)
VeryBig buffers, 4520 bytes (total 11, permanent 10, peak 11 @ 00:29:22):
11 in free list (0 min, 100 max allowed)
8098 hits, 0 misses, 0 trims, 1 created
0 failures (0 no memory)
Large buffers, 5024 bytes (total 1, permanent 0, peak 1 @ 00:29:36):
1 in free list (0 min, 10 max allowed)
0 hits, 0 misses, 0 trims, 1 created
0 failures (0 no memory)
Huge buffers, 18024 bytes (total 5, permanent 0, peak 5 @ 00:29:22):
5 in free list (4 min, 10 max allowed)
0 hits, 0 misses, 0 trims, 5 created
0 failures (0 no memory)

Re: Cisco 2951 router issues

roncro — Fri, 27 Oct 2023 12:00:13 GMT

Hello Paul,

Upgrading the software, that means downloading a newer version of

"System Bootstrap, Version 15.0(1r)M13, RELEASE SOFTWARE (fc1)"  or of "flash0:c2951-universalk9-mz.SPA.151-4.M4.bin"

(does one need a subscription for that?)

thanks,

Ron

Re: Cisco 2951 router issues

balaji.bandi — Fri, 13 Oct 2023 18:21:41 GMT

If you like to download the software if your account CCO entitled then you can download

you need to download only IOS Image, Until the release notes ask you to upgrade ROMMON you do not need to upgrade that.

You can download 15.6 or 15.7 if you are entitled to download.

Re: Cisco 2951 router issues

roncro — Fri, 13 Oct 2023 18:25:10 GMT

Hello BB,

I don't have a service contract for that router, so it looks like I can't download the updates.

thanks,

Ron

Re: Cisco 2951 router issues

roncro — Fri, 27 Oct 2023 12:23:13 GMT

Also, the newest one doesn't look like it will fit, not enough room?

this is what is on there:

1 -rw- 66547544 May 28 2012 04:30:02 -06:00 c2951-universalk9-mz.SPA.151-4.M4.bin
2 -rw- 2814 May 28 2012 04:37:14 -06:00 cpconfig-29xx.cfg
3 -rw- 3000320 May 28 2012 04:37:28 -06:00 cpexpress.tar
4 -rw- 1038 May 28 2012 04:37:36 -06:00 home.shtml
5 -rw- 122880 May 28 2012 04:37:46 -06:00 home.tar
6 -rw- 1697952 May 28 2012 04:37:58 -06:00 securedesktop-ios-3.1.1.45-k9.pkg
7 -rw- 415956 May 28 2012 04:38:08 -06:00 sslclient-win-1.1.4.176.pkg
8 -rw- 1142 Jul 24 2012 07:07:52 -06:00 FCZ1622702R_20120724014232364.lic
9 -rw- 97911952 Oct 28 2015 06:44:34 -06:00 c2951-universalk9-mz.SPA.154-1.T1.bin




show version  shows me the running version:

System image file is "flash0:c2951-universalk9-mz.SPA.151-4.M4.bin"

so there are things I don't need (I think), looks like I don't need

cpexpress.tar, home.tar (and do I need securedeskop-ios or sslclient-win

and there's a c2951-universalk9-mz that's newer then what's running?

thanks,

Ron

Re: Cisco 2951 router issues

paul driver — Fri, 13 Oct 2023 19:37:34 GMT

Hello
As long as you have a valid licence you will be okay

Re: Cisco 2951 router issues

roncro — Fri, 27 Oct 2023 12:05:50 GMT

Ok, thanks, I am trying to make room now.

Maybe I should first see if I can make

c2951-universalk9-mz.SPA.154-1.T1.bin

the current running image, since

flash0:c2951-universalk9-mz.SPA.151-4.M4.bin

is the one in use.

Then after that worked, delete

151-4-mM4

one.. and try the

156/157?

(I wonder why it is on there, maybe it's corrupted)

thanks,

Ron

Re: Cisco 2951 router issues

paul driver — Fri, 27 Oct 2023 12:09:28 GMT

Hello
Yes install the new image and set the boot variable to run it as default.


Example:  xxx.bin file
Copy new ios to flash via tftp:

copy tftp:xxxxxxx.bin flash:

verify /md5 flash:xxxx.bin

dir flash:
sh bootvar
conf t
no boot system
boot system flash:xxxnNEWxx.bin
boot system flash:xxxnOLDxx.bin
exit
wr

reload

rtr should boot to new image, as/when your happy delete the old image from flash.

Re: Cisco 2951 router issues

roncro — Fri, 27 Oct 2023 12:15:12 GMT

I am going to try that;

the one that is running now is

 flash0:c2951-universalk9-mz.SPA.151-4.M4.bin

There is another one located on

flash: c2951-universalk9-mz.SPA.154-1.T1.bin

(but don't know the state)

and I have also

 c2951-universalk9-mz.SPA.156-3.M9.bin

(but not on flash)

So with the above I want to switch to the

c2951-universalk9-mz.SPA.154-1.T1.bin

to see if it works. Then back up the

c2951-universalk9-mz.SPA.151-4.M4.bin

with tftp and delete it.

Thendo the same thing again with

c2951-universalk9-mz.SPA.156-3.M9.bin

thanks!

Ron

Re: Cisco 2951 router issues

roncro — Fri, 27 Oct 2023 12:24:04 GMT

btw: trying to back stuff up on the tftp server, but get some weird errors.

Charon-2951#copy flash0:c2951-universalk9-mz.SPA.154-1.T1.bin tftp

Address or name of remote host []? 192.168.2.8

Destination filename [c2951-universalk9-mz.SPA.154-1.T1.bin]?

%Error opening tftp://192.168.2.8/c2951-universalk9-mz.SPA.154-1.T1.bin (No such file or directory)

I guess I am doing something wrong

Ron

Re: Cisco 2951 router issues

roncro — Fri, 27 Oct 2023 12:18:09 GMT

I tried following the instructions.

The router/2951 doesn't know

sh bootvar

(it doesn't recognize

bootvar

) can I just skip it and proceed from the conf t(erminal) on? (also, flash doesn't exist, but flash0: (dir flash doesn't work, dir flash0 does)

thanks,

Ron

Re: Cisco 2951 router issues

roncro — Fri, 27 Oct 2023 12:21:47 GMT

Hello Paul,

the

show bootvar

the 2951 doesn't seen to recognize

bootvar

Could I just skip it? and continue ? Also I think it doesn't recognize 'flash' it's called flash0 on mine (dir flash doesn't work, dir flash0 does work.

Also with the

boot system

calls, why do I need to use both the new and the old one in the call?

boot system flash:xxxnNEWxx.bin
boot system flash:xxxnOLDxx.bin  ?

Shouldn't I just use the new one?

thanks!

Ron

Re: Cisco 2951 router issues

roncro — Fri, 27 Oct 2023 12:25:30 GMT

Update:

I adapted the commands, with wat I saw on my router, that seemed to work. So I have the newerish IOS running now. (I am wondering still, if I can save the old image to my ftp server to save it?) Just in case.

If I delete the oldest IOS, and put the new one

(c2951-universalk9-mz.SPA.156-3.M9.bin)

on it I'd have 4Mb left or so, is that a good idea?

thanks,

Ron