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Beginner

ACL syntax for default route?

What is the correct syntax to identify a default route with an ACL?  FYI, I'm putting together an EIGRP offset list and it seems that only ACLs are permitted to identify routes.  

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VIP Mentor

Re: ACL syntax for default route?

Hello,

 

try:

 

access-list 1 permit 0.0.0.0

 

 

9 REPLIES 9
VIP Advisor

Re: ACL syntax for default route?

Hello


@davinci wrote:

What is the correct syntax to identify a default route with an ACL?  FYI, I'm putting together an EIGRP offset list and it seems that only ACLs are permitted to identify routes.  

What are you trying to accomplish?
If you want to offset all networks from an interface you can use a offset-list 0 no need for acl. or maybe as its eigrp you could manipulate the delay for a preferred eigrp path



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future
Beginner

Re: ACL syntax for default route?

I have a def. route being redistributed from BGP into EIGRP at two different sites. As a result, I'll have 2 def. route coming from from 2 different sites with AD 170.  In order to have better control over which def. route is preferred within enterprise, I want to use offset lists so that backup location external EIGRP def. route will be inferior.

VIP Advisor

Re: ACL syntax for default route?

Hello

Using a standard acl with 0.0.0.0 i guest will match the default but no so sure it will also match all routes and not just a default just like an offset-list 0 probably need to test it to validate my thinking is it as it isn't specific to what rtr is advertising the route, You could also try using an extended acl that will allow you to match on the advertising router and the network(s) you wish to filter(the default route)

example:
Ip access-list extended Offset
permit ip host (advertising eigrp rtr) host 0.0.0.0 

router eigrp xx
offset list Offset in xxx 



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future
Beginner

Re: ACL syntax for default route?

Ok, what I'm looking for is the ACL equivalent of ip prefix-list DEFAULT-ONLY 10 permit 0.0.0.0/0
VIP Mentor

Re: ACL syntax for default route?

Hello,

 

try:

 

access-list 1 permit 0.0.0.0

 

 

Beginner

Re: ACL syntax for default route?

thanks, on a side note... if route isn't matched within ACL offset list is that traffic dropped or passed along with def. EIGRP metrics?

Enthusiast

Re: ACL syntax for default route?

 

offset-list is used for traffic manipulation or engineering. effect is on match. 

no other prefixes are affected by it

Beginner

Re: ACL syntax for default route?

thanks, so I tested this in GNS3 and your syntax worked.  This syntax also works too with same results:

 

ip access-list standard 60

permit host 0.0.0.0

 

 

Here's my IOS

R4#sh version
Cisco IOS Software, 3700 Software (C3725-ADVENTERPRISEK9-M), Version 12.4(15)T7, RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2008 by Cisco Systems, Inc.
Compiled Wed 13-Aug-08 21:36 by prod_rel_team

ROM: ROMMON Emulation Microcode
ROM: 3700 Software (C3725-ADVENTERPRISEK9-M), Version 12.4(15)T7, RELEASE SOFTWARE (fc3)

R4 uptime is 1 week, 6 days, 23 hours, 8 minutes
System returned to ROM by unknown reload cause - suspect boot_data[BOOT_COUNT] 0x0, BOOT_COUNT 0, BOOTDATA 19
System image file is "tftp://255.255.255.255/unknown"


This product contains cryptographic features and is subject to United
States and local country laws governing import, export, transfer and
use. Delivery of Cisco cryptographic products does not imply
third-party authority to import, export, distribute or use encryption.
Importers, exporters, distributors and users are responsible for
compliance with U.S. and local country laws. By using this product you
agree to comply with applicable laws and regulations. If you are unable
to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:
http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

If you require further assistance please contact us by sending email to
export@cisco.com.

Cisco 3725 (R7000) processor (revision 0.1) with 249856K/12288K bytes of memory.
Processor board ID FTX0945W0MY
R7000 CPU at 240MHz, Implementation 39, Rev 2.1, 256KB L2, 512KB L3 Cache
4 FastEthernet interfaces
DRAM configuration is 64 bits wide with parity enabled.
55K bytes of NVRAM.

Configuration register is 0x2102

R4#

Enthusiast

Re: ACL syntax for default route?


just a note: usually we use Prefix-list not ACL 'cause of prefixes are more flexible
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