route map...

this doyle topology and it's artificial delay makes a nice segue into route maps...

r2#trace 10.1.6.1
Type escape sequence to abort.
Tracing the route to 10.1.6.1
VRF info: (vrf in name/id, vrf out name/id)
  1 10.1.2.1 16 msec 20 msec 8 msec
  2 10.1.1.2 8 msec 28 msec 8 msec
  3 10.1.6.1 8 msec 32 msec *

according to this trace, the constraints of the delays and our own sanity, the path to r4 from r2 is going to take the long way, bypassing the straight shot through 10.1.4...

r2#sh ip eigrp topo 10.1.6.0/24
EIGRP-IPv4 Topology Entry for AS(1)/ID(10.1.5.2) for 10.1.6.0/24
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 768
  Descriptor Blocks:
  10.1.2.1 (Serial1/0), from 10.1.2.1, Send flag is 0x0
      Composite metric is (768/512), route is Internal
      Vector metric:
        Minimum bandwidth is 1544 Kbit
        Total delay is 30 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 2
        Originating router is 10.1.6.2
  10.1.5.1 (Serial1/1), from 10.1.5.1, Send flag is 0x0
      Composite metric is (2048/1024), route is Internal
      Vector metric:
        Minimum bandwidth is 1544 Kbit
        Total delay is 80 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 3
        Originating router is 10.1.6.2


note also the route through 10.1.4 isn't even hitting the charts because of that delay... r5 hates it too, and it's directly connected...


r5#sh ip eigrp topo 10.1.4.0/24
EIGRP-IPv4 Topology Entry for AS(1)/ID(10.1.4.1) for 10.1.4.0/24
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 5120
  Descriptor Blocks:
  0.0.0.0 (Serial1/0), from Connected, Send flag is 0x0
      Composite metric is (5120/0), route is Internal
      Vector metric:
        Minimum bandwidth is 1544 Kbit
        Total delay is 200 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 0
        Originating router is 10.1.4.1

but since we love the route through 10.1.4 because i said so, we're going to force a way through there... sorry, eigrp...

r5(config)#access-list 1 permit 10.1.2.0 0.0.0.255
r5(config)#route-map thisway
r5(config-route-map)#match ip add 1
r5(config-route-map)#set ip next-hop 10.1.4.2
r5(config-route-map)#exit
r5(config)#int s1/2
r5(config-if)#ip policy route-map thisway
r5(config-if)#end
*Sep 16 11:39:40: PR-RP: Set Serial1/2 policy_routemap=thisway; cached_map=thisway

r5#debug ip policy 1
Policy routing debugging is on for access list 1
r5#

r2#ping 10.1.6.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.6.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/11/12 ms
r2#trace 10.1.6.1
Type escape sequence to abort.
Tracing the route to 10.1.6.1
VRF info: (vrf in name/id, vrf out name/id)
  1 10.1.2.1 24 msec 12 msec 8 msec
  2 10.1.4.2 8 msec 24 msec *

r5#
*Sep 16 11:47:37: IP: s=10.1.2.2 (Serial1/2), d=255.255.255.255, len 67, policy match
*Sep 16 11:47:37: IP: route map thisway, item 10, permit
*Sep 16 11:47:37: IP: s=10.1.2.2 (Serial1/2), d=255.255.255.255 (Serial1/0), len 67, policy routed
*Sep 16 11:47:37: IP: Serial1/2 to Serial1/0 10.1.4.2

note with record how the ping goes across 10.1.4 but comes back the long way...

r2#ping
Protocol [ip]:   
Target IP address: 10.1.6.1
Repeat count [5]: 2
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface: 10.1.2.2
Type of service [0]:
Set DF bit in IP header? [no]:
Validate reply data? [no]:
Data pattern [0xABCD]:
Loose, Strict, Record, Timestamp, Verbose[none]: record
Number of hops [ 9 ]:
Loose, Strict, Record, Timestamp, Verbose[RV]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 2, 100-byte ICMP Echos to 10.1.6.1, timeout is 2 seconds:
Packet sent with a source address of 10.1.2.2
Packet has IP options:  Total option bytes= 39, padded length=40

Reply to request 0 (36 ms).  Received packet has options
 Total option bytes= 40, padded length=40
 Record route:
   (10.1.2.2)
   (10.1.4.2)
   (10.1.6.1)
   (10.1.1.2)
   (10.1.2.1)
   (10.1.2.2) <*>
   (0.0.0.0)
   (0.0.0.0)
   (0.0.0.0)
 End of list

Reply to request 1 (24 ms).  Received packet has options
 Total option bytes= 40, padded length=40
 Record route:
   (10.1.2.2)
   (10.1.4.2)
   (10.1.6.1)
   (10.1.1.2)
   (10.1.2.1)
   (10.1.2.2) <*>
   (0.0.0.0)
   (0.0.0.0)
   (0.0.0.0)
 End of list

Success rate is 100 percent (2/2), round-trip min/avg/max = 24/30