From: sean@ttank.com
Date: Tue Sep 03 2002 - 17:45:06 GMT-3
Sequence is the key here.
As you type in ping cmd to R12's loopback, nothing comes as the closest
source interface.
So, using the logic we talked about like below, IOS happens to source the
icmp packets
from R9's ehter0. Only then happens the local policy routing, which will
throw the packets
out of R9's serial0 onto R12's serial0. In other words, when the default
next-hop policy kicks
in, the icmp packets are already well formed and sourced out of R9's
ehter0.
When the packets get to R12, we all know how and why they end up their
journey at the
packet bucket.
HTH
- Sean Liu
CCIE, CCNP, CCDP, CCSE,
AIX-CATE, CNE, MCSE+I
Think Tank Systems, LLC
|--------+------------------------->
| | "Volkov, Dmitry|
| | (Toronto - |
| | BCE)" |
| | <dmitry_volkov@|
| | ca.ml.com> |
| | |
| | 09/03/2002 |
| | 04:34 AM |
| | |
|--------+------------------------->
>------------------------------------------------------------------------------------------------------------------------|
| |
| To: "'sean@ttank.com'" <sean@ttank.com> |
| cc: ccielab@groupstudy.com, emonk@att.net |
| Subject: RE: local policy routing |
>------------------------------------------------------------------------------------------------------------------------|
Sean,
>
> Dmitry,
>
> What you thought is still true, that is a router will source
> packets from IP of interface closest to destination.
> What happens here is, when you ping loopbacks on R12 from R9,
> neither eth0 nor ser0 is closer to the
> destinations (7.7.7.7 or 160.160.160.160),
Right, but we have "default" next-hop configured in route-map and
Serial on R9 is closest to next-hop.. Why it wouldn't source from there ?
;)
You can say - this logic is by design. Ok, I'm just wondering what is logic
(sourcing packets) exactly ?
> by default, IOS sources packets from LAN interfaces.
I would add the following: It sources from LAN interfaces with lowest IP.
If there are no LAN interfaces , it sources from Loopback with lowest IP.
If there are no loopbacks or ethernet, but several Serial interfaces
it sources from serial closest to destination.
Do You know why ? and where this behavior (dependance on int type/IP)
described ??
> Then local policy routing kicks in and sends it on to the default
> next hop at 50.100.1.12 on R12's ser0. What really fails the pings is
> because R12 does not have a return route to R9's eth0 network.
Yes, I understand this.
Thanks You,
Dmitry
> - Sean Liu
>
> CCIE, CCNP, CCDP, CCSE,
> AIX-CATE, CNE, MCSE+I
>
> Think Tank Systems, LLC
>
>
>
>
>
> |--------+------------------------->
> | | "Volkov, Dmitry|
> | | (Toronto - |
> | | BCE)" |
> | | <dmitry_volkov@|
> | | ca.ml.com> |
> | | Sent by: |
> | | nobody@groupstu|
> | | dy.com |
> | | |
> | | |
> | | 09/02/2002 |
> | | 08:45 PM |
> | | Please respond |
> | | to "Volkov, |
> | | Dmitry (Toronto|
> | | - BCE)" |
> | | |
> |--------+------------------------->
>
> >-------------------------------------------------------------
> -----------------------------------------------------------|
> |
> |
> | To: "'Edward Monk'" <emonk@att.net>
> |
> | cc: ccielab@groupstudy.com
> |
> | Subject: RE: local policy routing
> |
>
> >-------------------------------------------------------------
> -----------------------------------------------------------|
>
>
>
> Yes Edward,
>
> On both sides route-map will work.
> That I know..
> I always thought that router sources packets from IP of
> interface closest
> to
> destination.
> Looks like it depends on type of interface when we have local policy
> enabled
>
> Thanks,
>
> Dmitry
>
> > -----Original Message-----
> > From: Edward Monk [mailto:emonk@att.net]
> > Sent: Monday, September 02, 2002 11:37 PM
> > To: 'Volkov, Dmitry (Toronto - BCE)'; ccielab@groupstudy.com
> > Subject: RE: local policy routing
> >
> >
> > Dmitry,
> >
> > You need a route back. If you apply the route-map to both
> > sides it will
> > work. The route-map matches all packets so no changes needed.
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> > Behalf Of
> > Volkov, Dmitry (Toronto - BCE)
> > Sent: Monday, September 02, 2002 7:28 PM
> > To: 'ccielab@groupstudy.com'
> > Subject: local policy routing
> >
> > Hello group,
> >
> > Could You please explain me what is wrong here R9(s0)----(s0)R12:
> > (I can't ping loopbacks on R12 from R9)
> >
> > R9#
> > interface Ethernet0
> > ip address 170.240.8.1 255.255.255.0
> > !
> > interface Serial0
> > ip address 50.100.1.9 255.255.255.0
> > no fair-queue
> > !
> > ip local policy route-map test
> > ip classless
> > no ip http server
> > !
> > route-map test permit 10
> > set ip default next-hop 50.100.1.12
> >
> > sh ip ro
> > 170.240.0.0/24 is subnetted, 1 subnets
> > C 170.240.8.0 is directly connected, Ethernet0
> > 50.0.0.0/24 is subnetted, 1 subnets
> > C 50.100.1.0 is directly connected, Serial0
> > r9#
> >
> >
> > R12#
> > !
> > interface Loopback0
> > ip address 7.7.7.7 255.255.255.0
> > !
> > interface Loopback1
> > ip address 160.160.160.160 255.255.255.0
> > !
> > interface Serial0
> > ip address 50.100.1.12 255.255.255.0
> > !
> > ip classless
> > no ip http server
> >
> > Thanks,
> >
> > Dmitry
> > _________________________________________________________________
> > Commercial lab list: http://www.groupstudy.com/list/commercial.html
> > Please discuss commercial lab solutions on this list.
> _________________________________________________________________
> Commercial lab list: http://www.groupstudy.com/list/commercial.html
> Please discuss commercial lab solutions on this list.
This archive was generated by hypermail 2.1.4 : Mon Oct 07 2002 - 07:43:43 GMT-3