EIGRP Filter

=====================  EIGRP FILTER  ========================================

1. offset-list

- the offset-list feature in EIGRP is used to modify the metric on a per_route basis or a per-interface basis.

+ Only apply theo chieu " in "

+ Only increases delay value.

+ accesslist used "permit"

+ change value delay

+ Metric increase = K3 * offset * (K5 / (reliability + K4))

+ In Eigrp it’s used to add to the existing delay value                

#offset-list [ACL] {in|out} {offset} {interface}

router eigrp 1

offset-list 1 in 2147483647 s0/0

!

access-list 1 permit 1.1.1.0 0.0.0.255

=============================================================================

2. distribute-list

- Filters all routes matching the ACL or prefix-list

distribute-list {ACL | prefix} {in|out}

std acl:

router eigrp 1

distribute-list 1 in Serial0/0

!

access-list 1 permit 1.1.1.0 0.0.0.255

extended acl:

In R2 :

access-list 100 deny ip host 1.1.1.1 host 10.1.12.1

access-list 100 deny ip host 1.1.2.1 host 10.1.12.1

access-list 100 deny ip host 1.1.3.1 host 10.1.12.1

access-list 100 permit ip any any

!

router eigrp 100

distribute-list 100 in Serial0/0

line : access-list 100 deny ip host 1.1.1.1 host 10.1.12.1

+ prevent R2 learn 1.1.1.1 from R1 ( 10.1.12.1 )

- Filters all routes to/from a neighbor

distribute-list gateway {prefix-list} {in|out} {interface}

- Filters prefix from a specific source from entering the routing table

distribute-list prefix {prefix-routes} gateway {prefix-source} {in|out}

- Changes the distance for both internal and external EIGRP routes

distance eigrp {ad-internal} {ad-external}

- Using Route-maps

  

router eigrp 100

distribute-list route-map FILTER_ON_TAGS in

!

route-map FILTER_ON_TAGS deny 10

match tag 4  { match length , match interface .... }

!

route-map FILTER_ON_TAGS permit 20

=====================================================================

3. Using Admin distance:

distance {AD} {address} {wildcard} {acl#|aclname}

- any source

• Filter route internal

Distance {AD} eigrp internal  external

• Filter all

access-list 1 permit 1.1.1.0 0.0.0.255

!

router eigrp 100

distance 255 0.0.0.0 255.255.255.255 1

-specific per neighbor

access-list 1 permit 1.1.1.0 0.0.0.255

!

router eigrp 100

distance 255 10.1.12.1 0.0.0.0 1

=======================================================================

4. Using redistribution with route-maps

router eigrp 100

redistribute rip metric 100000 100 255 1 1500 route-map RIP_TO_EIGRP

!

ip prefix-list VLAN_43 seq 5 permit 204.12.1.0/24

!

route-map RIP_TO_EIGRP permit 10

match ip address prefix-list VLAN_43

set tag 4

!

route-map RIP_TO_EIGRP permit 20

==================================================================