From: Jongsoo.Kim@Intelsat.com
Date: Thu Mar 17 2005 - 14:32:11 GMT-3
Tim
My understanding is that you need to send traffic from vlan A to R-B or R-C
or beyond and with prec = 3 toward Rc or its PVC.
If you use extend ACL, you can define source, destination, prec in one line.
I am guess the fonig amy be something like this
access-list 100 permit ip "vlan A network" "R-B or R-C or beyond network"
precedence 3
route-map 10 IF-IP-PREC-3-GOTO-RC
match ip address 100
set ip next-hop R-C R-B ===> (I think this makes if R-C is not available,
then R-B will be the next hop.( I am not 100 % sure))
route-map 20 IF-IP-PREC-3-GOTO-RC ===> (this line is not necessary for
policy routing as its default behavior is permit, which is opposite to
rouet-map)
int f/r p2m
service-policy out IF-IP-PREC-3-GOTO-RC
Regards
Jongsoo
-----Original Message-----
From: ccie2be [mailto:ccie2be@nyc.rr.com]
Sent: Thursday, 17 March, 2005 11:55 AM
To: Group Study
Subject: MQC vs Policy Routing
Hi guys,
This problem stumped me. I didn't like either of the 2 solutions that came
to mind and would like to hear your thoughts.
=============================
Figure 1
/ -- R-B
| ---- e0/0 R-A -- p2m f/r other networks with different
major network addresses
\ -- R-C
==============================
Figure 2
R-A e0/0 ---- vlan 1 ------ R-d ----- R-e
==============================
R-A is connected to vlan 1 via it's e0/0 interface and to R-d via vlan 1 and
other subnets beyond that. (Fig 2)
R-A is also connected to R-B and R-C via p2m f/r and can reach other
networks behind R-B and R-C (Fig 1)
I want R-A to forward packets that originate on vlan 1 and are heading to
R-B or R-C or beyond and have an ip prec of x to take the pvc to R-C if it's
available.
If the pvc or R-C is down, take the other pvc. All networks behind R-B or
R-C can be reached via either pvc.
I'm not sure how to config this.
I thought of policy routing but this was the problem I couldn't figure out.
Suppose packets originating on vlan 1 weren't suppose to head towards R-B or
R-C? Wouldn't they just end up going to R-C or R-B only for these routers
to send them back to R-A. ? And, thus waste bandwidth?
Here's the pseudo code:
route-map 10 IF-IP-PREC-3-GOTO-RC
match ip-prec-3 and source = vlan1
set ip next-hop R-C
route-map 20 IF-IP-PREC-3-GOTO-RC
***********************************************
The other solution I thought of was to use MQC:
Assume the dlci to R-B = dlci-B and the dlci to R-C = dlci-C.
Here's the pseudo code:
access-list 100 permit ip vlan1 any prec 3
class-map match-all IP-PREC
match int e0/0 <-- Is this needed?
match ip address 100
policy-map IP-PREC
class IP-PREC
set fr-dlci <pvc-C>
int f/r p2m
service-policy out IP-PREC
*****************************************************
I never used the set fr-dlci command before and so I'm not 100% sure this
solution actually works but I pretty sure it does. (I put an acl on R-C and
then did some pings and saw the matching packets go up but I didn't do any
other testing.)
Q?
Will both solutions actually work?
Is the MQC solution better?
Is there a better solution I didn't think of?
TIA, Tim
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