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What is new? Last 5 articles ...

17. Port security on access layer switchport

Port security is feature that enable permit or deny traffic for end user PCs connected to access layer switch. Port security enable specify a group of valid MAC address on port. If maximum secure MAC address  is reached then security violation modes lead to protect, restrict or shutdown of port.

 

There are 3 ways how to configure port security:

1) Static secure MAC addresses - manually configured with

   switchport port-security mac-address MAC_ADDRESS

16. Administrative Distance and route source preference

In environment with 2 or more enabled routing protocols must be present mechanism for selection of routing sources that are learned. What routing protocol obtained routes for remote network will be introduced to routers routing table? That is a big question.

 

Administrative Distance in short AD is considered parameter that will break the tie and say about trustworthiness of routing source.

 

 

15. PPP and Frame relay in small network

PPP and Frame relay are protocols operating at data link layer used in segment of private WAN connection. PPP enable establish communication through serial link between cisco and noncisco device where can not be used proprietary HDLC cisco encapsulation. Frame relay networks offer packet switched technology in providers network.  This article will focus on simple implementation of PPP serial link and Frame relay link in office environment.


 

 

UNIX and posix like OS administration

This section focus on Unix or posix like OS administration. Articles cover area of basic CLI commands with appropriate explanation, deployment of application layer services as FTP, SFTP, WWW, E-mail, NFS, SAMBA file server or LDAP, SSH access an certification key generation.

16. CUCM 8 - Call hunt configuration

As it was in CUCME call hunt enable one hunt pilot number to distribute calls to members of hunt list. For reference please read our article http://www.cdesigner.eu/content/12-hunt-groups-how.

 

CUCM configuration for call hunt is more flexible and robust. During creation of hunt environment we going through this steps:

10. Rootbridge election process in STP enabled environment

In redundant L2 topology STP ensures loop  free path for frames traveling among endpoints blocking redundant paths that cause a loop.

 

9. Small office configuration scenario with VLAN and internet access nr. 3

New network scenario consist of one branch router with default routing to ISP. WAN internet access use PPP serial link with old PAP authentication. Office hosts are separated in 3 VLAN. Vlan 1 remain default, VLAN 2 is staff and for guests is reserved guest VLAN 3. Administrator use Admin Laptop for direct console CLI access. Switched network remain very simple, there is only one switch extended with old hub Hub0 (clients C and D share same subnet but also same collision domain).

8. Small office configuration scenario with VLAN and internet access nr. 2

Small office network in our scenario separate hosts on 3 VLAN (1, 2 and 3). Because one part of network is really old we can here found shared segment with old L1 hub. Redundant link in switched topology introduced between S2 and S3 must be monitored with STP. 

Scenario consist of:

  • PPP link with CHAP authentication between Office and ISP router

              Office part of config:

6. OSPF DR and BDR slection in multiaccess network segment examination lab.

Multi access networks create challenge for OSPF because:

a) create multiple adjacencies (one adjacencies for every pair of router)

b) extensive flooding of LSA - link state advertisement

for n -routers it is n(n-1)/2 adjacencies.

 

Because link-state protocols flood their link state packets during cold start or when there is a change in the topology possible solution is election of DR designated router.

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