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Cisco ACL Revision

Access Control Lists (ACL) Access Control Lists are used to: Prioritise traffic Restrict or reduce updates Provide basic security Block types of traffic Access control list placement Standard ACLs – Place as close to destination as possible. Extended ACLs – Place as close to source of traffic as possible. Only one ACL per port per direction is allowed. ACL are more efficient on outbound port. If a packet does not match the ACL statement then it will be implicitly denied. Once a packet matches an ACL statement no other checks are made, it is permitted.   ACL IOS commands Standard ACLs – Used to permit or deny an e

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Top 10 Show Commands for Cisco Routers

The Absolute top 10 show Commands Everybody Needs To Know in Cisco Routers Some commands in the Cisco router configuration are just irreplaceable. The ‘show’ commands are the most widely used in Cisco routers. Here is a list of the 10 mostly used of these ‘show’ commands. 1. show running-config This command is your true best friend. It shows the complete configuration that is running currently. 2. show startup-config This command shows the configuration that is saved on the NVRAM. It is helpful in knowing the configuration that will be applied the next time the routers is reloaded. 3. show interface This command shows status and stati

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EIGRP tunnel template Cisco

Cisco tunnel template – EIGRP Below is a tunnel template used to provide a single site failover between two remote locations. interface Tunnel[SITE TUNNEL KEY] description —- [SITE] & [REMOTE SITE] —- ip address [SITE TUNNEL IP] ip flow ingress tunnel source [LOCAL PROVIDER INTERFACE IP] tunnel destination [SITE PROVIDER IP] tunnel key [TUNNEL KEY] interface Tunnel[SITE2 TUNNEL KEY] description —- [SITE] & [REMOTE SITE2] —- ip address [SITE2 TUNNEL IP] ip flow ingress tunnel source [LOCAL PROVIDER INTERFACE IP] tunnel destination [SITE2 PROVIDER IP] tunnel key [SITE2 TUNNE

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Understanding the Cisco IOS File Name Convention

Cisco IOS naming conventions can seem a bit confusing, however to avoid bricking a device its important that you have a full understanding of the Cisco IOS naming conventions. Before planning an upgrade or install of an IOS file, it is very important that you check the name of each IOS file. The IOS file name is usually similar to this form xxxx-yyy-ww.aaa-bb.bin 1. The xxxx is the platform. For example: c1005 – For 1005 platform c1600 – For 1600 platform c1700 – For 1700, 1720, and 1750 platforms c2500 – For 25xx, 3xxx, 5100, and AO (11.2 and later only) platforms c2600 – For 2600 platform c2800 – For Catalyst 2800 platform c29

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ip tcp adjust-mss causing browsing problems

Cisco Router causing browsing problems after installing a cisco router I saw that users were not able to browse the internet, strangely enough they could open the home page or the landing page of a website but could browse no further, as in click a link on the site or view the next page. after a few hours of troubleshooting it turned out to be a really simple fix all I had to do was make a minor tweak to the mass adjust. ip tcp adjust-mss 1300 What does the ip tcp adjust-mss do. Any packet that contains an initial tcp header flowing through your router will be examined against the mss. The mss in the header will be lowered to this amount if

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Cisco CCNA exam Cram Sheet

Cisco CCNA exam Cram Sheet General Networking Port Numbers Port Number Layer 4 Protocol Suite Application 20 TCP FTP Data 21 TCP FTP Program 23 TCP Telnet 25 TCP SMTP 53 TCP/UDP DNS 69 UDP TFTP 80 TCP HTTP Ping Responses ! – Reply from target address . – Timeout U – Destination unreachable C – Congestion experienced I – User interrupt ? – Unknown packet type & – Packet lifetime exceeded Ethernet 5-4-3 rule – Between any 2 nodes there can only be a maximum of 5 segments, 4 repeaters and only 3 of those segments can have hosts. Loop back address –, tests

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CCNA basic switch configuration commands

Cisco basic configuration commands (CCNA) Command descriptions switch>? The ? works here the same as in a router Used to get the list of all available commands switch>enable User mode, same as a router switch# Privileged mode switch#disable Leaves privileged mode switch>exit Leaves user mode switch#show version Displays information about software and hardware. switch#show flash: Displays information about flash memory (will work only for the 2900/2950 series). switch#show mac-address-table Displays the current MAC address forwarding table. switch#show running-config Displays the current configuration in DRAM.

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