From: John Wong (johnwk@unimelb.edu.au)
Date: Sun Oct 24 2004 - 20:37:14 GMT-3
Hi all,
I've narrowed the problem down to 2 routers i.e. R3 and R5 (FR switch).
To make troubleshooting easier, I removed all the frame-relay settings
on both router's serial interface and just setup a simple HDLC
back-to-back connection. i.e.
R5 Serial3 (DCE) ----------- R3 Serial0
Cable type is a V.24 (RS-232) cable with DCE end on R5.
"show interface serial" on both routers shows nothing wrong.
R5#sh int s3
Serial3 is up, line protocol is up
Hardware is HD64570
Description: To R3 Serial0
Internet address is 30.0.0.5/24
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
Last input 00:00:03, output 00:00:05, output hang never
Last clearing of "show interface" counters 00:11:07
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/2/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
83 packets input, 9492 bytes, 0 no buffer
Received 78 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
78 packets output, 4532 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
R3#sh int s0
Serial0 is up, line protocol is up
Hardware is HD64570
Description: To R5 Serial3
Internet address is 30.0.0.3/24
MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
Last input 00:00:02, output 00:00:02, output hang never
Last clearing of "show interface" counters 00:06:09
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/2/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
43 packets input, 2482 bytes, 0 no buffer
Received 43 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
48 packets output, 10258 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
Now here's where it gets really strange. When I performed an extended
ping with 1500 bytes from R5 to R3 and also from R3 to R5, it will
fail. When I did a "debug ip packets", I found that R5 was able to
send ICMP echo to R3 and R3 replied with ICMP reply BUT it never
made it to R5. Debug on R3 shown below :-
Oct 25 07:26:32 SGT: IP: s=30.0.0.5 (Serial0), d=30.0.0.3 (Serial0), len 1500, rcvd 3
Oct 25 07:26:32 SGT: IP: s=30.0.0.3 (local), d=30.0.0.5 (Serial0), len 1500, sending
So it seems to be some asymmetric transmission problem. i.e. R5 is able
to send to R3 at 1500 bytes but R3 cannot send at 1500 bytes to R5. OR
R5 is not able to receive 1500 bytes (??) while R3 can receive 1500 bytes.
Problem occurs when ping bytes size is set to 509 bytes and above.
Anyone have any clue as to what's happening?
Thanks.
John Wong wrote:
> A very big thank you to all who've replied.
>
> I found out that the problem may not lie with the IS-IS configuration.
> It may be something to do with the hardware or cable. I couldn't do a ping
> with anything above 508 bytes from R3 to R7 over the serial/FR interface
> but could ping all the way up to 1500 bytes from R1. So I suspect it could
> be the serial card or the cable used from R3 to the FR switch/router.
>
> Cheers.
>
>
> Wam wrote:
>
>> John,
>> i would check as follows..
>>
>> 1. Assuming FR switch is fully meshed, i would check "show fram-relay
>> map" to make sure static mapping is as required (between R3 and R7),
>> even though "no frame inv-arp and frame map" statements are there.
>>
>> 2. From your debug output, i would be concerned if my peer interface
>> parameters like MTU are in sync.
>>
>> -Wam
>>
>> John Wong <johnwk@unimelb.edu.au> wrote:
>> Hi all,
>>
>> Need help from you Gurus on a strange IS-IS problem I am encountering
>> at the moment. Any help is much appreciated.
>>
>> I am getting the below message on a hub router in a FR network
>> configured to run IS-IS :-
>>
>> Oct 24 21:19:13 SGT: %CLNS-3-BADPACKET: ISIS: LAN L2 hello, packet
>> (1500) or wire (988) length invalid from DLCI 703 (Serial0/2.1)
>>
>> The adjacency is stuck at the Init stage in R3 (spoke) and not appearing
>> at all in R7 (hub).
>>
>> Strange thing is that I have 2 identically configured routers (R1 & R3)
>> as the spokes and the hub router (R7) can establish adjacency with one of
>> them (R1) but not the other (R3). Both R1 & R3 are of the same hardware
>> platform and runs the same version of IOS image.
>>
>> Relevant configuration as below :-
>>
>> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>> !
>> hostname R1
>> !
>> interface Serial0
>> no ip address
>> encapsulation frame-relay
>> no frame-relay inverse-arp
>> !
>> interface Serial0.1 multipoint
>> ip address 192.168.1.1 255.255.255.0
>> ip router isis frame-relay map clns 107 broadcast
>> frame-relay map ip 192.168.1.3 107 broadcast
>> frame-relay map ip 192.168.1.7 107 broadcast
>> !
>> router isis net 47.0200.0102.5500.0001.00
>>
>> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>> !
>> hostname R3
>> !
>> interface Serial0
>> no ip address
>> encapsulation frame-relay
>> no frame-relay inverse-arp
>> !
>> interface Serial0.1 multipoint
>> ip address 192.168.1.3 255.255.255.0
>> ip router isis frame-relay map clns 307 broadcast
>> frame-relay map ip 192.168.1.1 307 broadcast
>> frame-relay map ip 192.168.1.7 307 broadcast
>> !
>> router isis net 47.0000.0102.5500.0003.00
>>
>> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>> !
>> hostname R7
>> !
>> interface Serial0/2
>> no ip address
>> encapsulation frame-relay
>> no frame-relay inverse-arp
>> !
>> interface Serial0/2.1 multipoint
>> ip address 192.168.1.7 255.255.255.0
>> ip router isis isis priority 120
>> frame-relay map clns 703 broadcast
>> frame-relay map clns 701 broadcast
>> frame-relay map ip 192.168.1.1 701 broadcast
>> frame-relay map ip 192.168.1.3 703 broadcast
>> !
>> router isis net 47.0100.0102.5500.0007.00
>>
>> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>>
>> R1#sh clns neigh
>> System Id Interface SNPA State Holdtime Type Protocol
>> R7 Se0.1 DLCI 107 Up 7 L2 IS-IS
>>
>> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>>
>> R3# sh clns neigh
>> System Id Interface SNPA State Holdtime Type Protocol
>> 0102.5500.0007 Se0 DLCI 307 Init 9 L2 IS-IS
>>
>> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>>
>> R7#sh clns neighbors System Id Interface SNPA State Holdtime Type
>> Protocol
>> R1 Se0/2.1 DLCI 701 Up 24 L2 IS-IS
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