Archive for the ‘OUTPUT-101’ Category
June 6, 2010
From a question on groupstudy; the following output was posted of a Cisco 2600 that did not boot up even after the Flash was upgraded to 32MB??????
System Bootstrap, Version 12.1(3r)T2, RELEASE SOFTWARE (fc1)
Copyright (c) 2000 by cisco Systems, Inc.
C2600 platform with 65536 Kbytes of main memory
program load complete, entry point: 0x80008000, size: 0x1c8a8e4
Error : memory requirements exceed available memory
Memory required : 0x04746F90
*** System received a Software forced crash ***
signal= 0x17, code= 0x4, context= 0x80080630
PC = 0x0, Vector = 0x0, SP = 0x0
System Bootstrap, Version 12.1(3r)T2, RELEASE SOFTWARE (fc1)
Copyright (c) 2000 by cisco Systems, Inc.
C2600 platform with 65536 Kbytes of main memory
program load complete, entry point: 0x80008000, size: 0x1c8a8e4
Error : memory requirements exceed available memory
Memory required : 0x04746F90
rommon 1 > dir flash:
File size Checksum File name
29928068 bytes (0x1c8aa84) 0x6ee9 c2600-adventerprisek9-mz.124-23.bin
rommon 2 >
What could the problem be?
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Posted in Hardware, OUTPUT-101 | Tagged c-2600 | 1 Comment »
December 24, 2009
Often knowing the necessary show commands is not enough, you need to understand the output.
Here is a good example and breakdown of each of the fields with the command:
show traffic-shape
VC = 'DLCI's'
Access List = 'Used to shape traffic of common type for separation'
Target Rate = 'CIR in bits'
Byte-Limit = 'Bc+Be ie the size the token bucket, express in BYTES'
Sustain bits/int = 'Bc value per Tc, (int is short for interval or Tc)'
Excess bits/int = 'Be value'
Interval (ms) = 'Tc value'
Increment (bytes) = 'How many bytes of token replenished each Tc, ie Bc value in bytes'
Adapt Active = 'Shows Adaptive shaping has been enabled. If a BECN is received, the flow is throttled back'
What else can be set about the configuration here?
The interface have 3 DLCI’s defined.
DLCI’s 413 and 405 have a CIR of 56k. This was not configured. This is default behaviour. When ‘frame-relay traffic-shaping’ is enabled each DLCI on that interface will be allocated a 56k CIR unless changed. Here it is clear that DLCI 403 has a map-class policy applied.
Oh and Merry Christmas guys 
Posted in Frame-Relay, OUTPUT-101, QOS | Tagged FRTS, OUTPUT-101 | Leave a Comment »
November 26, 2009
When BGP peers set up their session between them, they send an OPEN message containing optional parameters.
One optional parameter is capabilities. Possible capabilities are Multiprotocol extensions, route refresh, outbound route filtering (ORF), and so on. When the BGP peers exchange the Multiprotocol extension capability, they exchange AFI and SAFI numbers and thus identify what the other BGP speaker is capable of.
IPv6 in BGP is implementated via Multi-Protocol BGP (MPBGP) (RFC 2283), as is MPLS and VPN’s through two new attributes: MP_UNREACH_NLRI and MP_REACH_NLRI. The first two values in these two attributes contain the Address Family Identifier (AFI) and the Subsequent Address Family Identifier (SAFI).
| AFI |
Meaning |
| 1 |
IPv4 |
| 2 |
IPv6 |
.
| SAFI |
Meaning |
| 1 |
Unicast |
| 2 |
Multicast |
| 3 |
Unicast and multicast |
| 4 |
MPLS Label |
| 128 |
MPLS-labeled VPN |
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Posted in BGP, OUTPUT-101 | Tagged BGP, OUTPUT-101 | Leave a Comment »
September 7, 2009
Sometimes it is necessary to go back to the basics that we have already forgotten. You can identify six possible states in the interface status line of the show interfaces serial output:
- Serial x/y is up, line protocol is up
- Serial x/y is down, line protocol is down
- Serial x/y is up, line protocol is down
- Serial x/y is up, line protocol is up (looped)
- Serial x/y is up, line protocol is down (disabled)
- Serial x/y is administratively down, line protocol is down
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Posted in General info, OUTPUT-101 | Tagged OUTPUT-101 | Leave a Comment »
August 7, 2009
Several BGP timers can be used to tweak the BGP convergence in an IP/MPLS/VPN Network. A good understanding and side by side comparison will allow you to tweak BGP behavior.
BGP Scan Time:
#bgp scan-time {scanner-interval}
- Configures import processing of IPV4 unicast routing information from BGP routes into routing tables.
- The BGP scanner walks the BGP table and confirms the reachability of next hops.
- The BGP scanner process is also responsible for conditional advertisement check and performing route dampening.
- The Max / Default value = 60 sec. Range = 5-60 sec.
- Lowering the scan-time, can greatly improve BGP convergence, to almost IGP-like behaviour.
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Posted in BGP, OUTPUT-101 | Tagged BGP, OUTPUT-101 | Leave a Comment »
July 15, 2009
In the previous article I showed how useful Netflow can be, but that is only the beginning. The “verbose” output provides even more useful information, specifically the TOS-Byte. That field is necessary when you want to verify if QOS marking is correctly applied to traffic classes.
But first you have to understand a little about QOS (Quality of Service) and the TOS-byte/DS-Field in the IP header.
The IP header is defined in RFC 791, includes a 1-byte field called the Type of Service (ToS) byte. The ToS byte was intended to be used as a field to mark a packet for treatment with QoS tools. The ToS byte itself was initially further subdivided, with the high-order 3 bits defined as the IP Precedence (IPP) field. Bits 3 through 6 were not used very often, and bit 7 was never defined, so over time the entire ToS byte’s purpose was to hold the 3-bit IPP field. 3 bits (23 = 8 ) allowed 8 possible markings.
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Posted in General info, OUTPUT-101, QOS | Tagged OUTPUT-101, QOS | Leave a Comment »
July 14, 2009
Ever needed to track specific flow of information or find out what ports a application is using, or verify if your QOS is working correctly? Cisco Netflow is the answer.
NetFlow is a Cisco IOS application that provides a rich set of traffic statistics on packets flowing through the router, both ingress and egress. A NetFlow network flow is defined as a unidirectional stream of packets between a given source and destination. These key fields/statistics define a unique flow:
- Source IP address
- Destination IP address
- Source port number
- Destination port number
- Layer 3 protocol type
- Type of service (ToS)
- Input logical interface
If a packet has one key field different from another packet, it is considered to belong to another flow. Flows are stored in the NetFlow cache and does does consumes additional memory, but generally this is not to much of a problem. Netflow data could be exported, but here I’ll show how to use it on CLI and how to interpret it.
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Posted in General info, OUTPUT-101 | Tagged Netflow, OUTPUT-101 | Leave a Comment »
October 29, 2008
Error: The image in the archive which would be used to upgrade
Error: system number 1 does not support the same feature set.
Cisco it seems included this sanity check,as of 12.2(35), to prevent you from accidentally changing the feature set during a IOS upgrade, not a nice thing to happen on a production switch, when things go belly up.
You will get the above error when upgrading the IOS and changing the feature set. IE if you upgrade the image from IPBASE 12.2(35)SE5 to ADVIPSERVICESK9 12.2(25)SEE4.
So to bypass this, you can add the /allow-feature-upgrade parameter, to the archive download-sw command.
Example :
#archive download-sw /overwrite /allow-feature-upgrade tftp:10.1.1.1/c3560-advipservicesk9-tar.122-25.SEE4.tar
If you need more info on how to upgrade the IOS on a Cisco 3560, visit Cisco.
Posted in OUTPUT-101, Switching | Tagged OUTPUT-101 | Leave a Comment »
October 17, 2008
Debugging is one of the best tools to use when troubleshooting problems, but also the most dangerous tool if missused in production networks.
By limiting the debug capture only to the interface that you need, instead of all 100+ client interfaces, you mitigate the risk to a reasonable degree.
The following command enables conditional debugs for interface serial1/0. This means that only debugs for ser1/0 are displayed:
Rack1R1#debug interface s1/0
Condition 1 set
Rack1R1#sh debugging
TCP:
TCP Packet debugging is on
Condition 1: interface Se1/0 (1 flags triggered)
Flags: Se1/0
-
Note that the command ‘undebug all’ does not remove conditional triggers, only the normal debugs, ie like below only the the TCP Packet debugging has been removed:
Rack1R1#un all
Port Statistics for unclassified packets is not turned on.
All possible debugging has been turned off
Rack1R1#sh debug
Condition 1: interface Se1/0 (1 flags triggered)
Flags: Se1/0
-
To remove your conditional debug, use the following:
Rack1R1#undebug interface s1/0
This condition is the last interface condition set.
Removing all conditions may cause a flood of debugging
messages to result, unless specific debugging flags
are first removed.
Proceed with removal? [yes/no]: yes
Condition 1 has been removed
Rack1R1#sh debug
Rack1R1#
Posted in General info, OUTPUT-101 | Tagged Debug, OUTPUT-101 | Leave a Comment »
September 28, 2008
Error log:
%BGP-3-NOTIFICATION:received from neighbor 196.7.8.9 2/2 (peer in wrong as) 2 bytes 0064
Explanation:
The Obvious is true, a wrong ASN is configured, but there is more detail here. “2 bytes 0064″ : the 0064 is the received ASN in HEX, ie 0×0064 in HEX = 100 decimal.
The local router is expecting Neighbor 196.7.8.9 to come from a specific ASN, not ASN 100. Have a look at the “neighbor {IP} remote-as” command to confirm it is set correctly. If confederations are used, make sure your confederation-id is correct between the two EBGP peers.
Posted in BGP, OUTPUT-101 | Tagged OUTPUT-101 | Leave a Comment »
September 28, 2008
There are lots of really good blogs and forums out there that shows you how to setup all different kinds of networking stuff.
Being in a support team myself, I do find it frustrating sometimes, when looking for error codes, a specific output interpretation, or the meaning of a specific flag/field in a very common command. The obvious problem when searching for a specific flag in a common command, is the Google returns 100000+ links, all listing that part of a config, that has absolutely nothing to do, with what you looking for.
So I will try post detailed explanations of my experience and findings on troubleshooting that really helps.
Posted in OUTPUT-101 | Tagged OUTPUT-101 | Leave a Comment »
