Cisco Juniper MPLS Integration Problem.

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Mar 20th, 2007
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I had problem to integrate the Cisco router to the Juniper MPLS core network.

Cisco router is PE and Juniper M20 is P/PE router. The LDP is running fine between both routers, but the only problem faced is Cisco PE router do not receive "tag/label" from the Juniper router. Please refer to below capture.

Any advice what to check/verify when connecting Cisco and Juniper together in MPLS network.

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glsfb4-mbone#sh mpls ldp bind

glsfb4-mbone#sh mpls ldp bindings

tib entry:, rev 740

local binding: tag: imp-null

tib entry:, rev 742

local binding: tag: 383

tib entry:, rev 172

local binding: tag: 99

tib entry:, rev 744

local binding: tag: 384

tib entry:, rev 746

local binding: tag: 385

tib entry:, rev 748

local binding: tag: 386

tib entry:, rev 750

local binding: tag: 387

tib entry:, rev 174

local binding: tag: 100

tib entry:, rev 752

local binding: tag: 388

tib entry:, rev 176

local binding: tag: 101

tib entry:, rev 178

local binding: tag: 102

tib entry:, rev 180

glsfb4-mbone#sh mpls ldp discovery all

Local LDP Identifier:

Discovery Sources:


GigabitEthernet0/1 (ldp): xmit/recv


glsfb4-mbone#sh mpls ldp neighbor

Peer LDP Ident:; Local LDP Ident

TCP connection: -

State: Oper; Msgs sent/rcvd: 843/370; Downstream

Up time: 01:00:53

LDP discovery sources:

GigabitEthernet0/1, Src IP addr:

Addresses bound to peer LDP Ident:

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Harold Ritter Wed, 03/21/2007 - 06:59
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It appears thet the M20 is not sending any label in our direction. Are you by any chance filtering labels on the M20.

Hope this helps,

mheusinger Wed, 03/21/2007 - 07:48
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check, if there is an outbount LDP filter in the Juniper router:

LDP { export }

This could explain the described behaviour.

Regards, Martin

jiangu Thu, 03/22/2007 - 23:56
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By default, JUNOS LDP only advertises /32 loopback prefix-FEC bindings upstream, you need to explicitly configure egress policy under LDP to advertise other prefix-FEC mappings.

Side qeustion, why do we need the label mapping for other prefixes except loopbacks anyway? what application will need that?

Harold Ritter Fri, 03/23/2007 - 07:30
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I agree with you that advertising labels for loopback interface addresses is preferable in most cases. You can use "tag-switching advertise-tags" command on the IOS side to only allow loopback interface addresses to propagate.

Hope this helps,

tckoon@hp Tue, 03/27/2007 - 00:17
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Hi all, sorry for late reply.

Basically the VPN routes is sucessful advertised. The only problem is the next-hop ip (loopback) learn is not tag.

I can extended ping from to , but I cannot ping from to 172.16.1 as the next hop is, which is not tag/label. is LDP neighbor router loopback which is " POP-Tag".

glsfb4-mbone#sh ip ro vrf TEST

Routing Table: TEST

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is not set is subnetted, 3 subnets

C is directly connected, Loopback9930

B [200/0] via, 01:04:16

B [200/0] via, 01:04:16

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Harold Ritter Tue, 03/27/2007 - 05:59
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Did you make the change I recommended on glsfb3 to include all the interfaces under the LDP process as follow:

protocols ldp {

interface all;


JunOS will not announce a label for a given prefix (FEC) unless it has already received a label for that same prefix. So glbp3 basically needs to receive a label for from GLM-1 before it can advertise it to glbp4.

Hope this helps,

tckoon@hp Tue, 03/27/2007 - 06:26
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Not yet as the Juniper router is in production network and is under customer care. I need to advice him to do the change , but it may take time as they need to know is the change can cause any downtime to the network.

Will update it once the change take place.

Many thanks

Harold Ritter Tue, 03/27/2007 - 06:25
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Note that you do receive a "implicit null" label for (glbp3), which confirms that LDP is working properly between glbp3 and glbp4.

I notice that you are not using LDP in the core but RSVP instead. You could tunnel LDP over your MPLS TE tunnels by adding the ldp-tunneling command under each label-switch-path stanza as follow:

protocols {

mpls {

label-switched-path xxx {

from source;

to destination;





Note that this will have to be done at both end.

Hope this helps,

Ali Norouzi Tue, 12/21/2010 - 04:33
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jiangu I had same issue and by using your comment the problem resolved.

My desired application is MPLS forwarding. I want to forward all the traffic with MPLS lable.

Thank you,

Harold Ritter Fri, 03/23/2007 - 07:26
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Try "interface all" instead of "interface fe-0/1/0.0" under the "protocols ldp" stanza on the Juniper side.

This will most probably fix your issue.

Hope this helps, Sun, 01/16/2011 - 08:11
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If you can trying to ping a directly connected vrf interface which is on the juniper box, you need vrf-table-label configured under the vrf instance




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