c2921 router will not bring up fibre SFP

Unanswered Question
May 23rd, 2012

c2921 router will not bring up fibre SFP

I can't get two cisco 2921 routers to talk to each other

the setup works find in my testbed with a rj45 cross over cable between them or even with a WANEM cloud emulator(free tool).

after migrating from CU  to fibre they won't to talk to each other anymore. worse, both refuse to bring up their wan side fibre SFP.
the "media-type" sub i/f command was used to change to SFP from RJ45
after that, the EN SFP light appears on both routers, but no link light

sh int gi 0/1
GigabitEthernet0/1 is down, line protocol is down
  Hardware is CN Gigabit Ethernet, address is xxx(bia xxx)
  Description: ** TEST LINK
  Internet address is 1.1.1.2/30
  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, 1000Mb/s, media type is SX

the two routers are in different buildings and must pass through a middle building(#2)

B1 - 200m -- B2 -- 900m -- b3

R1 (in building 1) is 200m from building 2
R2 (in building 3) is 900M from building 2

R1 has a MM SFP in Gi 0/1
R2 has a SM SFP in Gi 0/1 as the distance is too far for MM


in building two we have used both a SM to MM media converter
and a layer two switch with SM and MM SFP,
both show similar results

R1(MM sfp) --MM cable-- (MM sfp) switch (SM sfp) --SM cable--(SM sfp)R2

on the switch( in Bld 2), we see links lights coming out of the two routers, for both SM and MM links, this is good and expected. no traffic is seen though

on either router, no link light is seen and both interfaces are down down. shut, no shut, does not bring them up

we have tried different SFP and cables, still no change

one google search mentions an undocumented ciso command to ignore incompatibale SFP, but that does not work in IOS 15

if we add a 3750 switch to the routers Gi 0/1 WAN side as a media converter, we get success.

each switch has two sfp, one Cu and the other MM or SM fibre .

the router "media-type" sub i/f command was used to change to RJ45 from SFP, after that, the SFP EN lights goes out(as expected) on both routers,

R1(CU)-(CU)3750(MM sfp) --MMcable-- (MM sfp) switch (SM sfp) --SMcable--(SM sfp)-(SM sfp)3750(CU)R2

why does this work and the connection on the rtr does not

sh int gi 0/1
GigabitEthernet0/1 is up, line protocol is up
  Hardware is CN Gigabit Ethernet, address is xxx(bia xxx)
  Description: ** TEST LINK
  Internet address is 1.1.1.2/30
  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, 1000Mb/s, media type is RJ45


this test is not practical in the deployed field and far too expensive

i am looking for a solution and want to know why the SFPs do not work in the routers

i tried two different MM SFP. neither one worked, though from SH INV, one can't tell them apart. on the CISCO site only this one is supported
glc-sx-mm, the SFP-GE-s is not supported on the 29xx rtr but is on the 3750 switch (;

================
%added SFP-GE-s SFP, the SFP-GE-s is not supported on the 29xx rtr but is on the 3750 switch
sh inv
NAME: "CISCO2921/K9 chassis", DESCR: "CISCO2921/K9 chassis"
PID: CISCO2921/K9      , VID: V03 , SN: xxxx

SFP-GE-s
NAME: "1000BASE-SX SFP", DESCR: "1000BASE-SX SFP"
PID: FTLF8519P2BNL-C6B , VID: B  , SN: xxxx
%============
%remove SFP and added glc-sx-mm SFP, this is the supported MM SFPO for the 29xx rtr
sh  inv

NAME: "1000BASE-SX SFP", DESCR: "1000BASE-SX SFP"
PID: SFBR-5766PZ-CS1   , VID:    , SN: xxx
============
Cisco IOS Software, C2900 Software (C2900-UNIVERSALK9-M), Version 15.0(1)M3, RELEASE SOFTWARE (fc2) 
Cisco CISCO2921/K9 (revision 1.0) with 475136K/49152K bytes of memory.
Processor board ID xxx
9 FastEthernet interfaces
3 Gigabit Ethernet interfaces
1 Virtual Private Network (VPN) Module
DRAM configuration is 64 bits wide with parity enabled.
255K bytes of non-volatile configuration memory.
500472K bytes of ATA System CompactFlash 0 (Read/Write)

License Info:
License UDI:
-------------------------------------------------
Device#   PID                   SN
-------------------------------------------------
*0        CISCO2921/K9          xxx
Technology Package License Information for Module:'c2900'
----------------------------------------------------------------
Technology    Technology-package          Technology-package
              Current       Type          Next reboot
-----------------------------------------------------------------
ipbase        ipbasek9      Permanent     ipbasek9
security      securityk9    Permanent     securityk9
uc            None          None          None
data          None          None          None

Configuration register is 0x2102

I have this problem too.
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walter baziuk Thu, 05/24/2012 - 04:29

yes, that was checked. between each site we ran 6 pair of either SM or MM.

two of the pairs are in use.

for these tests, we tried the remaining pairs.

we also shot a laser down the line for ensure the cables were good for each hop

see also that the switch that acts as media converter see link light from the far end C2921.

the c2921 seem to be the common problem.

Marvin Rhoads Thu, 05/24/2012 - 05:35

Please provide your interface configuration script for the SFP interfaces. Specifically I would be looking to see that you hard-code the speed command.

walter baziuk Thu, 05/24/2012 - 05:53

hello:

pls see the inline code.

there is NO speed on fibre SFP. they have no duplex either . all fibre SFP are fixed speed and full duplex

on the 3750 switches one can issue the command speed nonegotiate.

this command does not exist onthe rtr routers

Marvin Rhoads Thu, 05/24/2012 - 06:44

Yes I know a given SFP is fixed speed physically. Some IOS devices still require one to set the speed in the script to make it come up.

Sent from Cisco Technical Support iPhone App

walter baziuk Thu, 05/24/2012 - 06:50

with fibre sfp on a sw or rtr, the speed and duplex commands are disabled.

as they can't be changed, he IOS removes these two options

if the media-type is changed to RJ45, these options re appear

walter baziuk Fri, 05/25/2012 - 18:01

Problem solved.
MAJOR untested bug in IOS 15.0(1)M3 which was the default image when we bought the devices
*** AVOID IOS 15.0  series  ***

there are several bugs related to SFPs like:

does does recognize SFP
des not recognize some EHWIC cards such as, but not limited to EHWIC 1GE-SFP-CU

CSCtj35792   
c3900 : gigE SFP should switch to 1000/FD if other side has no nego
Externally found severe (Sev2) bug: M-More

CSCth28824  
c3945 GE shows DOWN/DOWN as compare to SFP
Externally found moderate (Sev3) bug: R-Resolved

They were fixed in 15.0(1)M4 or later

You can check the caveats for this IOS Release 15.0M:

http://www.cisco.com/en/US/docs/ios/15_0/release/notes/150MCAVS.html

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Posted May 23, 2012 at 8:09 PM
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