Cisco CCNP and CCIE Study Notes

Consider the following topology

Client -- R1 ---- R2 -- Gateway -- Web server (22.1.1.1)

There is a GRE tunnel between routers R1 and R2.

R1 has the following config

interface Tunnel1
 ip address 20.20.20.1 255.255.255.0
 keepalive 10 5
 tunnel source 10.10.10.1
 tunnel destination 10.10.10.2
!
interface Ethernet0
 ip address 10.10.10.1 255.255.255.0
 no keepalive

and router R2 has the following config

interface Tunnel1
 ip address 20.20.20.2 255.255.255.0
 keepalive 10 5
 tunnel source 10.10.10.2
 tunnel destination 10.10.10.1
!
interface Ethernet0
 ip address 10.10.10.2 255.255.255.0
 no keepalive

In addition, on router R2 the following additional config is seen -

interface ethernet0
 ip policy route-map mystery

route-map mystery permit 10
 match ip address 101
 set ip df 0

access-list 101 permit tcp 22.1.1.0 0.0.0.255 any

Now here are some questions regarding this set-up -
1. What purpose is the keepalive on the tunnel serving?
2. What is the route-map doing?
3. Think up a scenario for a problem that is being solved by policy routing in the example above.