ACL syntax for default route?

[davinci]

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.  

[paul driver]

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

[davinci]

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.

[paul driver]

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 

[davinci]

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

[Georg Pauwen · Accepted solution]

Hello,

try:

access-list 1 permit 0.0.0.0

[davinci]

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?

[Martin L]

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

no other prefixes are affected by it

[davinci]

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)
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Cisco 3725 (R7000) processor (revision 0.1) with 249856K/12288K bytes of memory.
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4 FastEthernet interfaces
DRAM configuration is 64 bits wide with parity enabled.
55K bytes of NVRAM.

Configuration register is 0x2102

R4#

[Martin L]

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