Transcript The OSI Model

Troubleshooting X.25 Calls
Troubleshooting X.25 Calls
X.25 Stack
Gcom_ssd
Processing Connect Request
User
Kernel
NPI Provider
NPI Connect Request
From SS_OP_CONN_REQ
Consult routing tables
•Address pattern
•User data pattern
•Least cost calculation
•Load balancing
NPI Call Routing
Choose an X.25 packet level
pktlvl.1
pktlvl.2
Process X.25 Call Request
DLPI User
Send downstream to LAPB
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Troubleshooting X.25 Calls
X.25 Stack
Gcom_ssd
Debugging Routing
User
Kernel
Gcom_stats -n -D0x42004
NPI Provider
0x40000 = Debug routing
0x02000 = Decode Call Req
0x00004 = Decode Clr Req
NPI Call Routing
pktlvl.1
pktlvl.2
DLPI User
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Troubleshooting X.25 Calls
X.25 Stack
Gcom_ssd
cmessages File
Debugging Routing
User
Kernel
Compare addresses
Compare user data
Route outgoing Connect Req
NPI Provider
Attempting route to '321' Minor LPA=0 PU-ID=0
Considering route to pktlvl.1: LPA=1 PUID=1 Up/Dwn=1
Comparing '321' to '*' Match
NPI Call Routing
...Comparing '00 00 00 00' to '00 00 00 00' Match, add to list
Comparing '321' to '100' Not match: pattern match failed
Considering route to pktlvl.2: LPA=2 PUID=2 Up/Dwn=1
pktlvl.1
pktlvl.2
Comparing '321' to '*2' Not match: pattern match failed
Comparing '321' to '200' Not match: pattern match failed
DLPI User
Choose X.25 Pkt Lvl
Route List:
Route to pktlvl.1: LPA=1 PUID=1 Up/Dwn=1 '*'
Call Request: UPA 1: pktlvl.1: Called='321' Calling=''
Send down stream
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Troubleshooting X.25 Calls
X.25 Stack
Gcom_ssd
cmessages File
Debugging Routing
User
Kernel
Route incoming X.25 Call Req
NPI Provider
NPI Call Routing
pktlvl.1
pktlvl.2
Called DTE address
Call Request: UPA 2: pktlvl.2: Called='321' Calling=''
Facilities:
42 08 08
packet size negotiation
43 02 02
window size negotiation
NPI-find-listener: lpa=2 pu_id=2 nsap="321" rnsap=""
? minor 1: lstn_lpa=0 lstn_pu_id=0 nsap="*" rnsap="*"
return minor 1
Success
Call Accept: UPA 2: pktlvl.2 LC 1: Called='' Calling=''
Facilities:
42 08 08
packet size negotiation
43 02 02
window size negotiation
DLPI User
X.25 LCN
Find a listening stream
Call Accept triggered
by user interaction
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Troubleshooting X.25 Calls
X.25 Stack
Gcom_ssd
cmessages File
Debugging Facilities
User
Kernel
An X.25 call fails with diagnostic information similar to the following.
NPI Provider
Received DISC_REQ: 0x83410307
Disc: Connection rejection-reason unspecified
Cause:
Invalid facility request
Diagnostic: Facility/registration code not allowed
Check the cmessages file for messages similar to the following.
NPI Call Routing
pktlvl.1
pktlvl.2
X.25 facility not allowed: 420808 X.2-selected[6]&0x10 = 0x0
This tells you that a facility was rejected because the selected structure index
[6] needed to have the 0x10 bit set, but it was zero. You can adjust your
configuration accordingly.
X.25 always prints a message like this when rejecting a Call Request packet
because of improper facilities.
DLPI User
Back to back test.
Call goes out on port 1
and comes in on port 2.
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Troubleshooting X.25 Calls
X.25 Stack
Gcom_ssd
cmessages File
Debugging Facilities
User
Kernel
You can cause X.25 to print more information about facility field checking by
using the following command to turn on a debug bit.
Gcom_stats -X0x1000
NPI Provider
NPI Call Routing
pktlvl.1
pktlvl.2
You will then see messages like the following.
Facils OK on port 1
send: pktlvl.1: packet type call_req
Facils invalid on port
send: X.25 window size isz=2 osz=2
send: X.25 packet size isz=8 osz=8
recv: pktlvl.2: packet type call_req
recv: X.25 validate_facil[6]&0x10: 420808
X.25 facility not allowed: 420808 X.2-selected[6]&0x10 = 0x0
recv: pktlvl.1: packet type clr_req
send: pktlvl.1: packet type clr_conf
recv: pktlvl.2: packet type clr_conf
2
DLPI User
Back to back test.
Call goes out on port 1
and comes in on port 2.
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Troubleshooting X.25 Calls
End of Presentation