Access Lists

[ElijahBaley]

Hi

There seems to be a bit of confusion with this in the Sybex book, so I just wondered if anyone can clear up once and for all:

1) Do you place Standard access lists nearest to the source or destination?

2) Do you place Extended access lists nearest to the source or destination?

Thanks for your help,

 

[netdesk53]

Hi Elija,

In the notes I have the Standard Access list should be nearest the destination and the Extended Access list should be nearest the source address

 

[Pavlos]

The Standard access lists should be nearest to destination and the Extended should be near to Source.

A Standard IP access list analyses the source address of the packet and matches it against the access list.

An Extended IP access list analyses the destination address of the packet and matches it against the access list.

A Standard IPX access list analyses the source AND DESTINATION address of the packet and matches it against the access list. CCNA
System/Network Administrator

 

[ecafracs]

access-list should be placed to the perfect location where the traffic should be filtered. If the situation requires that a traffic be filtered it should be evaluated as to where the exact interface of which router the filter would be placed.You can refer to the Cisco CCNA Study Guide by Wendell Odom and it is clearly explained in that book.
Sybex books indicates that extended access-list should be placed near the source, and standard access-list be placed at destination.

 

[atomicsushi]

A friend once told me - a way to remember this is ESD - (electro static discharge) hehe, but hey...

E - extended ---> S - Source/ S- Standard ----> D - Destination

So for extended ACL should be closer to the Source
Standard ACL is closer to Destination..

 

[balaganesh]

What they mention in the books is just the guide lines.the access lists should be applied where u intend to filter the packets. Now theres again the direction of the filter too ie; inbound and outbound. So practically the theory in these books makes no sense.
But, If u're preparing for the CCNA exam, then the answer is
1)Extended towards the Source
2)Standard towards the Destination

Sybex Book Sucks....try not to prepare with it....you MAY Pass the exam but fundamentally you'll be a Jackass.

--Ganesh
TopGun Technologies

http://www.topguntechnologies.com