Route optimization - Revision history

Heth: /* prefix lists */

2022-08-16T12:29:35Z

‎prefix lists

Heth: /* prefix lists */

2014-06-04T09:11:19Z

‎prefix lists

Heth: /* reditribution cavets */

2010-06-18T15:09:56Z

‎reditribution cavets

Heth: /* PBR: Policy Based Routing */

2010-05-03T10:34:57Z

‎PBR: Policy Based Routing

Heth at 06:38, 3 May 2010

2010-05-03T06:38:51Z

Heth: /* PBR: Policy Based Routing */

2010-05-03T06:27:27Z

‎PBR: Policy Based Routing

Heth at 05:41, 26 April 2009

2009-04-26T05:41:55Z

Heth: /* PBR: Policy Based Routing */

2009-03-25T10:50:15Z

‎PBR: Policy Based Routing

Heth: /* Routing loops */

2009-03-25T08:16:12Z

‎Routing loops

Heth: New page: = reditribution cavets = == Routing loops == === redistribute RIP into OSPF example === Consider the network below and follow the red update path. #Router A updates router B with RIP. Rou...

2009-03-25T08:15:36Z

New page: = reditribution cavets = == Routing loops == === redistribute RIP into OSPF example === Consider the network below and follow the red update path. #Router A updates router B with RIP. Rou...

New page

= reditribution cavets =
== Routing loops ==
=== redistribute RIP into OSPF example ===
Consider the network below and follow the red update path.
#Router A updates router B with RIP. Router B now learne the network 80.0.0.0/16.
**Please note that the administrative distance for RIP is 120.
#Router B now redistributes 80.0.0.0/16 into OSPF.
**Note that OSPF has an administrative distance of 110.
#Router B updates router C as an '''external''' OSPF route administrative distance 110
#Router C updates router D as an '''external''' OSPF route administrative distance 110
#Router D updates router E as an '''external''' OSPF route administrative distance 110
#Router E now has two router to 80.0.0.0/16
##Via RIP directly to Router A (Preferred route)
##Via OSPF to router D - Path D->C->B->A.
#Router E sends traffic to 80.0.0.0/16 to router D because OSPF(110) administrative distance is better than RIP's(120).
[[image:RIP_redistribute_into_OSPF.png|500px|none|thumb|RIP redistribution into OSPF example]]
==== Avoiding Routing loop ====
=== redistribute RIP into EIGRP example ===
With EIGRP we avoid the routing loop seen from OSPF above. EIGRP has two different administrative distances.
One for internal routes 90 and one for externally learned routes 170. 
Consider the network below and follow the red update path.
#Router A updates router B with RIP. Router B now learne the network 80.0.0.0/16.
**Please note that the administrative distance for RIP is 120.
#Router B now redistributes 80.0.0.0/16 into EIGRP.
**EIGRP has an '''internal''' route administrative distance of 90. and
**EIGRP has an '''external''' route administrative distance of 170.
#Router B updates router C as an '''external''' EIGRP route administrative distance 170
#Router C updates router D as an '''external''' EIGRP route administrative distance 170
#Router D updates router E as an '''external''' EIGRP route administrative distance 170
#Router E now has two router to 80.0.0.0/16
##Via RIP directly to Router A (Preferred route)
##Via EIGRP to router D - Path D->C->B->A.
#Router E sends traffic to 80.0.0.0/16 to router A because RIP(120) administrative distance is better than EIGRP external(170).
[[image:RIP_redistribute_into_EIGRP.png|500px|none|thumb|RIP redistribution into EIGRP example]]
= Distribute lists =
You can filter updates with distribute lists. The exampe below shows filtering of incoming updates. You can also filter outgoing updates.
[[image:distribute_list.png|500px|none|thumb|distribute list example]]
<pre>
hostname B
!
router rip
version 2
distribute-list 23 in
!
access-list 23 deny 90.0.0.0 0.0.255.255
access-list 23 permit any
</pre>
Router B Configuration of distribute list
 
<pre>
hostname E
!
router rip
version 2
distribute-list 3 in
!
access-list 3 deny 80.0.0.0 0.0.255.255
access-list 3 permit any
</pre>
Router E Configuration of distribute list
 
= PBR: Policy Based Routing =
PBR or Policy Based Routing gives more control and more options than distribute lists - see above.
PBR introduces the '''set''' command which set the interface or next-hop address to which the packet should be sent.
To select which packets should go where you can use the '''match''' command and match the based on for example source or destination addresses.

In the picture below the traffic from 192.168.1.0724 on E0 interface must route to ISP1 and
traffic from 172.16.1.0/24 on E1 must route to ISP1.
<pre>
hostname RTA
!
access-list 37 permit 192.168.1.0 0.0.0.255
access-list 48 permit 172.16.1.0 0.0.0.255
!
route-map ISP1 permit 10
match ip address 37
set interface s0/0
!
route-map ISP2 permit 20
match ip address 48
set interface s0/1
!
interface e0
ip policy route-map ISP1
!
interface e1
ip policy route-map ISP2
</pre>

[[Image:PBR1.png|500px|none|thumb|Policy Based Routing example]]

[[Category:Network]][[Category:Cisco]]

@@ Line 101: / Line 101: @@
 | 0.0.0.0/0 le 32 || All
 |}
 = PBR: Policy Based Routing =

@@ Line 64: / Line 64: @@
 Routes in routetable
 {|border=1 ;style="margin: 0 auto; text-align: center;cellpadding="5" cellspacing="0"
-|+ IPv4 Multicast Address groups
+|+ Address groups
 |- bgcolor=lightgrey
 ! Nr. !!Network
@@ Line 83: / Line 83: @@
 {|border=1 ;style="margin: 0 auto; text-align: center;cellpadding="5" cellspacing="0"
-|+ IPv4 Multicast Address groups
+|+ Address groups
 |- bgcolor=lightgrey
 ! Prefix list !!Matches in previos table

@@ Line 37: / Line 37: @@
 You can filter updates with distribute lists. The exampe below shows filtering of incoming updates. You can also filter outgoing updates.
 [[image:distribute_list.png|500px|none|thumb|distribute list example]]
-<pre>
+<source lang=cli>
 hostname B
+!
@@ Line 46: / Line 46: @@
 access-list 23 deny 90.0.0.0 0.0.255.255
 access-list 23 permit any
-</pre>
+</source>
 Router B Configuration of distribute list
 <br/><br/>
-<pre>
+<source lang=cli>
 hostname E
+!
@@ Line 58: / Line 58: @@
 access-list 3 deny 80.0.0.0 0.0.255.255
 access-list 3 permit any
-</pre>
+</source>
 Router E Configuration of distribute list
 <br/><br/>
@@ Line 68: / Line 68: @@
 In the picture below the traffic from 192.168.1.0/24 on E0 interface must route to ISP1 and
 traffic from 172.16.1.0/24 on E1 must route to ISP1.
-<pre>
+<source lang=cli>
 hostname RTA
+!
@@ Line 87: / Line 87: @@
 interface e1
   ip policy route-map ISP2
-</pre>
+</source>
 [[Image:PBR1.png|500px|none|thumb|Policy Based Routing example]]
+{{source cli}}
 [[Category:Cisco]][[Category:CCNP1]][[Category:CCNP]][[Category:IOS]][[Category:Network]]

← Older revision		Revision as of 05:41, 26 April 2009
Line 92:		Line 92:


−	[[Category:~~Network~~]][[Category:~~Cisco~~]]	+	[[Category:Cisco]][[Category:CCNP1]][[Category:CCNP]][[Category:IOS]][[Category:Network]]

@@ Line 1: / Line 1: @@
-= reditribution cavets =
+= redistribution cavets =
 == Routing loops ==
 === redistribute RIP into OSPF example ===

@@ Line 66: / Line 66: @@
 To select which packets should go where you can use the '''match''' command and match the based on for example source or destination addresses.
-In the picture below the traffic from 192.168.1.0724 on E0 interface must route to ISP1 and
+In the picture below the traffic from 192.168.1.0/24 on E0 interface must route to ISP1 and
 traffic from 172.16.1.0/24 on E1 must route to ISP1.
 <pre>

@@ Line 76: / Line 76: @@
 route-map ISP1 permit 10
   match ip address 37
-  set interface s0/0
+  set interface s0
+!
 route-map ISP2 permit 20
   match ip address 48
-  set interface s0/1
+  set interface s1
+!
 interface e0

@@ Line 4: / Line 4: @@
 Consider the network below and follow the red update path.
 #Router A updates router B with RIP. Router B now learne the network 80.0.0.0/16.
-**Please note that the administrative distance for RIP is 120.
+##Please note that the administrative distance for RIP is 120.
 #Router B now redistributes 80.0.0.0/16 into OSPF.
-**Note that OSPF has an administrative distance of 110.
+##Note that OSPF has an administrative distance of 110.
 #Router B updates router C as an '''external''' OSPF route administrative distance 110
 #Router C updates router D as an '''external''' OSPF route administrative distance 110
@@ Line 21: / Line 21: @@
 Consider the network below and follow the red update path.
 #Router A updates router B with RIP. Router B now learne the network 80.0.0.0/16.
-**Please note that the administrative distance for RIP is 120.
+##Please note that the administrative distance for RIP is 120.
 #Router B now redistributes 80.0.0.0/16 into EIGRP.
-**EIGRP has an '''internal''' route administrative distance of 90. and
+##EIGRP has an '''internal''' route administrative distance of 90. and
-**EIGRP has an '''external''' route administrative distance of 170.
+##EIGRP has an '''external''' route administrative distance of 170.
 #Router B updates router C as an '''external''' EIGRP route administrative distance 170
 #Router C updates router D as an '''external''' EIGRP route administrative distance 170
@@ Line 33: / Line 33: @@
 #Router E sends traffic to 80.0.0.0/16 to router A because RIP(120) administrative distance is better than EIGRP external(170).
 [[image:RIP_redistribute_into_EIGRP.png|500px|none|thumb|RIP redistribution into EIGRP example]]
 = Distribute lists =
 You can filter updates with distribute lists. The exampe below shows filtering of incoming updates. You can also filter outgoing updates.