RE: ATM CELL MODE SWITCHING - CAN NOT PING ACROSS

From: Roman Rodichev (roman@iementor.com)
Date: Sun Mar 29 2009 - 15:43:06 ART


Control VCs don't have to match on both sides (with both vp-tunnel and vpi
modes).

Backbone, I assume you have an ATM switch (dynamips?) in the middle and you
are switching VC 0/109 to VC 0/901. That's fine actually, your control VC
will come up. You can try show atm vc, and you should see VPI/VCI 0/109 PVC
with AAL5SNAP encapsulation UP on one side, and VPI/VCI 0/901 PVC with
AAL5SNAP encapsulation UP on the other side.

You have configured VPI mode VPI 0, this means that both sides will attempt
to assign ATM labels for the prefixes starting from VPI/VCI 0/33 and go up
(0/34, 0/35, etc.) Your atm switch must have VC 0/33 on R1 port switched to
VC 0/33 on R9 port, and so on (0/34 to 0/34, 0/35 to 0/35, etc). Or you can
just switch VPI 0 to VPI 0, but then, as Antonio mentioned, you'll need to
match control VCs on both sides (they are by default set to 0/32).

Once ATM-LDP detects matching label space range, you will start seeing
additional "TVCs" show up in the "show atm vc" output. (They'll be using
AAL5MUX encap). There will be a UNIDIRECTIONAL TV for each OSPF prefix that
you advertise. If you have 3 loopbacks on R1 and 3 loopbacks on R9, you
should see total of six TVCs (0/33, 0/34, 0/35, 0/36, 0/37, 0/38).
You can also use vp-tunnel mode in which case you could for example switch
VPI 0 to VPI 1 on your switch and then configure both sides like this:

R1
interface ATM1/0.1 mpls
 tag-switching atm vp-tunnel 0

R9
interface ATM1/0.1 mpls
 tag-switching atm vp-tunnel 1

control VC will automatically be set to 0/32 on R1 and 1/32 on R9

Roman Rodichev
5xCCIE #7927 (R&S, Security, Voice, Storage, Service Provider)
Instructor, Content Developer
ieMentor Corporation http://www.iementor.com
Y!M: roman7927

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Antonio Soares
Sent: Sunday, March 29, 2009 1:15 PM
To: 'backbone systems'; 'Cisco certification'; 'Cisco certification'
Subject: RE: ATM CELL MODE SWITCHING - CAN NOT PING ACROSS

With cell-mode, you must have a valid LDP/TDP adjacency. And here you have
mismatching control-vc's.

Regards,

Antonio Soares, CCIE #18473 (R&S)
amsoares@netcabo.pt

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
backbone systems
Sent: domingo, 29 de Margo de 2009 17:44
To: Cisco certification; Cisco certification
Subject: ATM CELL MODE SWITCHING - CAN NOT PING ACROSS

hi,

i have a scenario where R1 - R9 and connected over atm interface with
tag-switching......i am running ospf over the interface....Now my ospf
relationship is established successfully but i can not ping the routes
?????

Why is that....i am not getting it.....

R1

interface ATM1/0.19 tag-switching
 ip address 150.1.101.1 255.255.255.0
 no ip directed-broadcast
 no atm enable-ilmi-trap
 snmp trap link-status
 mpls ldp discovery transport-address interface
 mpls label protocol ldp
 tag-switching atm control-vc 0 109
 tag-switching atm vpi 0
 tag-switching ip

R9

interface ATM1/0.91 tag-switching
 ip address 150.1.101.9 255.255.255.0
 no ip directed-broadcast
 no atm enable-ilmi-trap
 snmp trap link-status
 mpls ldp discovery transport-address interface
 mpls label protocol ldp
 tag-switching atm control-vc 0 901
 tag-switching atm vpi 0
 tag-switching ip

let say on R9 i can see the routes

R9#sh ip route ospf
     1.0.0.0/32 is subnetted, 4 subnets
O 1.1.3.3 [110/50] via 150.1.101.1, 00:19:37, ATM1/0.91
O 1.1.2.2 [110/50] via 150.1.101.1, 00:19:37, ATM1/0.91
O 1.1.1.1 [110/2] via 150.1.101.1, 00:19:37, ATM1/0.91
     131.1.0.0/29 is subnetted, 3 subnets
O 131.1.12.0 [110/49] via 150.1.101.1, 00:19:37, ATM1/0.91
O 131.1.13.0 [110/49] via 150.1.101.1, 00:19:37, ATM1/0.91
O 131.1.23.0 [110/97] via 150.1.101.1, 00:19:37, ATM1/0.9

but i can not ping any of the routes?????

R9#sh mpls ldp dis
 Local LDP Identifier:
    1.1.9.9:0
    Discovery Sources:
    Interfaces:
        ATM1/0.91 (ldp): xmit/recv
            LDP Id: 131.1.13.1:1; IP addr: 150.1.101.1; no host route
R9#

i am missing something basic???? can anyone explain ?????

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