Shulou(Shulou.com)06/01 Report--

█ SNMP

█ Netflow

█ CCP=SDM

█ Syslog

Network troubleshooting-routing troubleshooting-IGP and BGP; switching troubleshooting

1. SNMP simple Network Management Protocol

1. Through SNMP, you can remotely configure, monitor and receive trap messages sent by the device, and debug and adjust according to the above contents.

2. Deployment

There are three different versions of SNMP: V1, V2C and V3. In the actual environment, it is recommended to choose version 2.

The first step is to set the group value of SNMP, which will be used as a value for remote verification during administration.

V3 is recommended in the actual environment; if you use V2C, be sure to configure ACL to restrict the permissions of only some users who can debug devices through SNMP, RO\ RW\ VIEW

The second step is to set the trap message

Select the source of TRAP messages. It is recommended to choose loopback.

Step 3: enable ifindex and MIB, enable interface index and management information base-facilitate the generation of MIB tree

Syslog log server

By turning on the log service function on the device, the resulting log is submitted to the log server, and the problem is judged by the log; fault recovery

Log level:

The smaller the number is, the more serious it is. Usually, if you can send level 7 logs, other logs can be sent by default.

First, enable the log service on the device.

Set the log server accept address

UDP is used by default to transfer log information; you can also use TCP to transfer information

Set the console log information level, and those level log information will be sent

Need to set send to send as trap message

Select the source interface to send log information

Set the local device log cache space size and entries

Netflow- flow Analyzer

It will mainly capture the traffic information of the interface and copy it to the target monitor; the monitor will view the traffic status in the network graphically.

Discovering the special traffic in the network is still for diagnosis and troubleshooting.

If you want to be safe and reliable, then use SCTP to implement, the data is secure, and there are redundant backup effects.

View validation

CCP graphic Interface deployment method

Network troubleshooting-IP routing troubleshooting-Rapid Construction of Enterprise Network Architecture and troubleshooting-CCNPTS2.0

First, the thinking of network troubleshooting.

1. Level by level-the phenomenon is hinted at that level

2. Enumerate possibilities

3. It is suggested to select a suitable demarcation point-usually the network layer is recommended as the demarcation point.

4. Separate processing of switching and routing

5. Before making a mistake, you should keep the original equipment configuration-copy a copy

6. Reasonable selection of tools-snmp, syslog

II. Methodology

1. The usual methods for routing problems

Ping----show----traceroute;---- first when the network communication fails.

Show-- found problems with routing-show interface, neighbor, policy, ACL, etc.

Show---- neighbor problem-look at the interface, authentication, ACL, match fields; at the same time, you can use debug when appropriate, but you don't have to use it as much as possible.

2. Multicast-ping---show---traceroute (mtrace)

Check IGMP content-pim---rp---- Multicast demarcation

3. IPV6---- address configuration is improper, IPV6 unicast routing is not enabled, and other configurations are improper.

4. Switch-show-1 checks vlan---2trunk----3vtp----4stp-5etherchannel-- before looking at redundancy protocols.

Third, the IGP of routing errors

1. Static route-incorrect network address, mask, outgoing interface and next-hop address; if there is a conditional tracking problem, the static route fails to add a table due to IP SLA tracking failure; administrative distance leads to

Incorrect static defaults can also lead to forwarding loops; imprecise static summary-forwarding loops

2 、 RIP

Why routes are not tabulated or not learned-no advertisements or advertised errors, inconsistent versions, ACL caused, automatic summarization enabled, manual summarization, passive interface, unicast neighbor error, authentication mismatch, offset list caused, distribution list caused; discontiguous subnet caused by RIPV1; frame Relay mapping error; pipe distance and metric

3 、 EIGRP

Neighbor relationship cannot be established: advertisement problem, AS inconsistency, router ID, ACL, K value, authentication, passive interface, unicast neighbor cause

Not available within the topology database: eigrp router ID consistency, distribution list cause, ACL cause, summary

Routes are not tabulated: AD, metric,

4 、 OSPF

Neighbors are unable to establish-

Consistent in down- key field mismatch, link problem, ACL, router ID, passive interface, interface network type, special area configuration, authentication

Always in the two-way- priority leads to

Stay in exstart-MTU

When using a large ping packet in EXCHANEG-MTU, it was found that it could not be reached during the link test-link congestion caused

LSDB database is incomplete: discontiguous area, special area, summary, LSDB data overload protection causes

No routing table: AD, metric, OSPF routing priority, distribution list refusal to add table, route flipping (link wobble, recursive loop-use tunnel; when discontiguous areas exist)

5. Reissue-metric metric specification, administrative distance modification, distribution list call, ACL definition, route-map matching problem, whether the prefix list is written correctly, is the location of the operation.

4. BGP with routing errors

1. Neighbor relationship establishment issues-AS, neighbor address, ttl, ACL filtering, update source, authentication; reachability

2. BGP routes are not selected in the BGP routing table-next-hop is unreachable, the routing process is unreasonable, and synchronization is not turned off

With RmurmurMustadtas-aggregate or suppress; caused by group attributes; AS-path; distribution list concerns, route-map filtering

3. BGP routes cannot be added to the IP routing table

AD, automatic summarization, manual summarization,

V. Exchange and troubleshooting

1. The VLAN- interface is not correctly divided into

2. VTP-trunk is not enabled, domain name is inconsistent, password is inconsistent, configuration version number, mode causes

3. TRUNK--- mode, inconsistent encapsulation protocol, inconsistent allowed VLAN list, inconsistent natvive VLAN.

4. Adjustment error when STP- interferes

5. Etherchannel- protocol error, negotiation error, rate error, duplex error

6. Redundancy-incorrect authentication, incorrect gateway address, ACL, different protocols between the two parties, inconsistent ACTIVE router and STP root bridge, inconsistent timer units, incorrect conditions set during tracking,

The reduced priority or weight variable is not specified correctly

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