policy based routing (pbr)
TRANSCRIPT
Policy-Based Routing (PBR)
Content- Before We Start- PBR Overview- How PBR Works- Route-Map Operation- PBR Configuration Procedure- PBR Configuration - Lab
Before We Start
- Destination Based Routing
- Routing from Net A/B to Net C/D via (R1 -> R5 -> R4)
PBR Overview
- Say goodbye to Destination Based Routing- Flexible routing packet decision based on traffic flows
- Overrides routing protocol next-hob decision
PBR Overview
- Routing from Net A to Net C via (R1 -> R5 -> R4)
- Routing from Net B to Net D via (R1 -> R2 -> R3 -> R4)
How PBR Works
- All packets received on an interface are considered for policyrouting
- Each packet is passed through a route-map- Each entry in a route-map has “match” and “set” clauses
- Match clauses are conditions to be met- Route-map is used for condition work
How PBR Works
If match src NetAset next-hob -> R5
If match src NetB
set next-hob -> R2
Route-Map Operation
route-map DEMO permit 10
match X Y Zmatch A
set Bset C
route-map DEMO permit 20match Qset R
route-map DEMO permit 30
If {(X OR Y OR Z)
AND A match}
Then {Set B AND C}
(and exit route-map)
ElseIf Q matches Then set R (and exit route-map)
ElseSet nothing (and exit route-map)
OR
OR
Route-Map Operation
- Match criteria on the same line mean a logical OR condition
- Multiple match and set criteria on separate lines indicates an AND condition
- A route-map statement without any match statements will be considered matched.
- Like an access list, an implicit deny any appears at the end of a route map.
PBR Configuration Procedure
- Define and name the route map with the route-mapcommand.- Define the conditions to match (the matchstatements).- Define access-list for packet identifying
- Define the action to be taken when there is a match (the set statements).
- Define which interface the route map will be attached to using the ip policy route-map interface configuration command.
PBR Configuration - Lab
PBR Configuration – Lab
Configuration on R1
- Create access-list
ip access-list extended Net7-Net4
permit ip 7.7.7.0 0.0.0.255 4.4.4.0 0.0.0.255
!
PBR Configuration – Lab
Configuration on R1
- Configure route-map
route-map DEMO permit 10match ip address Net7-Net4
set ip next-hop 192.168.12.2
!
route-map DEMO permit 20
!interface FastEthernet6/0
PBR Configuration – Lab
Configuration on R1
- Apply route-map into interface
interface FastEthernet6/0
ip policy route-map DEMO
!
PBR Configuration – Lab
Traceroute output from Network 7.7.7.7
- Before Apply into interface
traceroute 4.4.4.4 source 7.7.7.7
Type escape sequence to abort.
Tracing the route to 4.4.4.4
1 192.168.16.1 20 msec 12 msec 12 msec (R1)
2 192.168.15.5 12 msec 36 msec 28 msec (R5)
PBR Configuration – Lab
Traceroute output from Network 7.7.7.7
- After Apply into interface
traceroute 4.4.4.4 source 7.7.7.7
Type escape sequence to abort.
Tracing the route to 4.4.4.4
1 192.168.16.1 12 msec 20 msec 20 msec (R1)
2 192.168.12.2 30 msec * 34 msec (R2)
3 192.168.23.3 32 msec * 36 msec (R3)
4 192.168.34.4 68 msec 56 msec 52 msec (R4)
5 192.168.45.5 56 msec 68 msec 60 msec
Thanks