Poor man's bandwidth management - floating static question

Hello,

for a particular installation I have set up two internet
connections - one via leased line with fixed static IP addresses,
the other one with PPPoE and dynamic IP addresses.

The latter is a typical consumer product, i.e. "dirt cheap",
high bandwidth downstream and billed flat. The leased line
is a "business product" and offers less bandwidth, but
symmetrical and with lower RTTs and better SLAs.

The customer intends to use the cheap line for HTTP downloads
as long as it is available. This was not that difficult to set
up via policy routing:

1. the leased line:
-------------------
interface FastEthernet1
description leased line uplink
ip address x.y.z.42 255.255.255.252

ip route 0.0.0.0 0.0.0.0 x.y.z.41 250

interface Vlan3
description static network assigned by provider
ip address x.y.z.57 255.255.255.248
ip nat inside
ip route-cache policy
ip policy route-map no-http

See below for the NAT and policy config.

2. The cheap line:
------------------
interface FastEthernet0
description TDSL-Flat
no ip address
pppoe-client dial-pool-number 1

interface Dialer1
description TDSL-Flat 1
ip address negotiated
ip mtu 1448
ip nat outside
ip virtual-reassembly
encapsulation ppp
dialer pool 1
dialer idle-timeout 0
dialer enable-timeout 2
dialer persistent
dialer-group 1
... (deleted PPP auth parameters)

ip route 0.0.0.0 0.0.0.0 Dialer1
dialer-list 1 protocol ip permit

ip nat inside source list nat interface Dialer1 overload

ip access-list extended nat
permit ip x.y.z.56 0.0.0.7 any
deny ip any any

So we are NATing the official IP addresses assigned by the provider
for the leased line for all traffic that is sent out the cheap one.

3. The policy route-map
-----------------------
ip access-list extended no-http
deny tcp any any eq www
permit ip any any

route-map no-http permit 10
match ip address no-http
set ip next-hop x.y.z.41

This sends anything but traffic destined to port 80 out the
leased line and leaves traffic to port 80 alone, so it's
send out the cheap line.

The entire setup works as intended but for one minor point.
In case the cheap PPPoE line fails, we want to use the
leased line for HTTP traffic. I intended to do this
via a floating static route, hence the two default route
entries you see above.

Unfortunately it seems not to work that way. If I administratively
shutdown Dialer1, the result is as expected. The route to Dialer1
is deleted from the routing table and the route to x.y.z.41 is
used.

But this is not the common mode of failure of that PPPoE line.
If I simulate a failure on the cheap provider's side by
administratively shutting down Fa0, the Dialer1 obviously
times out and shuts down, eventually. Yet, the default
route to Dialer1 is not deleted. The Dialer1 interface
stays "up, line protocol is up (spoofing)", so the route
stays in the routing table.


Any hints on how to solve this greatly appreciated.

Thanks,
Patrick

 

Hello,

never mind, I found a solution:

int di1
description this is the cheap leased line that fortunately has got a fixed static IP address
dialer persistent
...
!
! track the static IP
track 1 ip route w.x.y.z 255.255.255.255 reachability
!
ip route 0.0.0.0 0.0.0.0 Dialer1 track 1

Kind regards,
Patrick

 

PBR w/ tracking options. If your next hop on the PPoE is a public
hop, you may need to block ping to that address out of the other
router, but this should work if your feature set supports it:

http://www.cisco.com/en/US/tech/tk364/technologies_configuration_example09186a0080211f5c.shtml

 

Hello,

Though this is not needed in my particular situation (see my other
post), it looks really interesting. Thanks for the link.

Kind regards,
Patrick