Could NAT be an option?

Jean-Christophe Varaillon
------------
ALTEC Telecoms - NOC
14, Patmou, 151 23 Maroussi, Greece
Tel:    +30 210 6872932
Fax:    +30 210 6872904
E-mail: [EMAIL PROTECTED]
ICQ:    264-755-242

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED]
Sent: Thursday, March 22, 2007 12:12 AM
To: swinog@swinog.ch
Subject: [swinog] MPLS VRF source routing (inter-vrf routing)

hi all

i've got some nice cisco bugs / features / whatever.

some prerequisites:

- 2 VRFs: vrf blue and vrf red
- both vrfs have a different default route.
- a PPP session / user terminating in vrf blue

a specific route (10.0.1.0/29) is routed over static route (e.g. radius
avpair) over the ppp session (vrf blue).
this route is imported to vrf red by importing rd values and route-map 
filtering. 
so the connectivity from the red vrf to the vrf blue is working (one way).

so, the goal (and this is the problem) is traffic souring that specific route 
should go back to vrf red.

how i thought would be the simplest way to do it: policy routing.

interface virtual-access123
 ip policy route-map set-vrf-red
...
!

access-list 110 permit 10.0.1.0 0.0.0.7 any

route-map  set-vrf-red permit 10
 match ip address 110
 set vrf red
!

would be the nicest way of doing this.

now the but: if you put the policy on the virtual-template / radius profile the 
session starts flapping (connect/disconnect/connect/disconnect....). so: not 
usable.

my other approach was:

interconnect vrf blue with vrf red by a vlan / interface.
assume on vrf blue: fastethernet0/0 with 11.0.0.1/30 connnected to vrf red with 
fastethernet0/1 with 11.0.0.2/30.

modifying the route map to:

route-map  set-vrf-red permit 10
 match ip address 110
 set interface fastethernet0/0
 set ip next-hop 11.0.0.2
!

this will stop the flapping (disconnect/connect/disconnect...) of the ppp 
session and the whole routing works as expected.... BUT: somewhen it stops 
working because of one thousand possible CEF bugs ;-(

i have to put "no ip route-cache cef" on the interconnection interface, then it 
works. some hours later (as already said) it stops working. when i do again "no 
ip route-cache cef" on the interface it works some other hours.

i've tried several IOS for the C7200series and the only half-way working 
version is the 12.4T (or even 12.3T).


so, now the big question to the community:

1) do you see any other working way doing source-routing from one vrf to 
another vrf?
(there's a vrf source routing command, but i think this will really not
scale)

2) do you have encountered the same CEF bugs? (i have seen them on 7206,
1841 and 2851 series routers)


how cisco tells me to do it:
http://www.cisco.com/en/US/products/sw/iosswrel/ps1838/products_feature_
guide09186a0080296409.html


i would be glad to get some input from you guys.

greetings


-steven
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