TE in MPLS question

Hi All,
To enable TE in MPLS, should I need to enable RSVP in every hop or just the head end and tail end? (I think it should be every hop) And when I see the TE information, it said that TE just support in 7500 series routers or above, did it mention just the head end and tail end routers or routers in every hop?Thank You!
Best Regards
Teru Lei

You need to enable RSVP on any interface you might potentially use to create the TE Tunnel.
BTW: MPLS TE is also supported on smaller platform.

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MPLS question

Hi all. We are in the midst of rolling out Mpls to 5 of our remote sites. 3 sites will have a cir of 10 mbps, 1 100mbps, and another 250 mbps. I am planning on running ospf in each site. My question is, will a 2821 router at each site be sufficient. Voice and data will be in use, so traffic shaping/qos will need to take place on these routers. Will this work. Thanks for your help.

Ah, you didn't mention you were using Metro Ethernet connections. 3750 will easily handle 100 or 250 Mbps.
As for tips for QoS, insure your voice is sent first. All data could be placed in a normal class or you could split it, with the 3 remaining classes, into critical, normal and scavenger if using non ES ports. Doubtful you need to do much more if using one of the ES ports, although it would be nice if you could do FQ in class default like you can on WAN routers but don't believe you can.
QoS document: http://www.cisco.com/application/pdf/en/us/guest/netsol/ns432/c649/ccmigration_09186a008049b062.pdf
Latest 3750 QoS config guide section: http://www.cisco.com/en/US/products/hw/switches/ps5532/products_configuration_guide_chapter09186a0080878de4.html

Some MPLS questions, agian

I . when I read the "Label Distribution topic" I getting in trouble with this problem:
- What are the differents between PE and P routers? (in Label distribution mechanism).
- When distrubute Label, which Table dose PE (or P) base on ?
And I feel not sure to anwser those questions :
QUESTION NO: 1
How does a PE-router operating in the default frame mode distribute labels?
A. The PE-router distributes a label for every destination in its FIB.
B. The PE-router only distributes labels for destinations inside the MPLS domain.
C. The PE-router only distributes labels for destinations outside the MPLS domain.
D. The PE-router does not distribute labels. Label distribution is only done by the core
LSR.
==> can you explain for me: what is called "default frame-mode"? in the default frame-mode is "PHP" is enabled by default ?
QUESTION NO: 2
How could you check for potential MTU size issues on the path taken by a PE-to-PE
LSP?
A. Because MPLS packets are label switched, MTU problems can only be detected by the
user applications.
B. Use the ping vrf command with packet size set to the largest MTU along the path
and DF bit set from the local PE-router to ping the remote PE-router.
C. Use the ping vrf command with packet size set to the smallest MTU along the path
and DF bit set from the local PE-router to ping the remote PE-router.
D. Because MPLS packets are label switched, packets are automatically fragmented and
reassembled by the PE-routers.
Therefore, there are no potential MTU issues.
==> I choose B in this question, is it correct ?
Thanks.

MPLS can work on two modes Frame mode and Cell mode.
Routers by default support frame mode.ATM switches and routers with ATM interface support cell mode.
PHP means Penultimate Hop.PHP is a term use to refer to node which is one HOP before the destination.e.g
R1-R2-R3-R4,your destination is on R4 in that case R3 is acting as PHP.It pops the label and sends it out as IP packet.
The PE router assigns the labels to all its destination learned through IGP.However BGP routes gets the label through their next hop e.g If you learn 120K BGP routes through single next hop.All the BGP routes will be having one label.
There is a feature called BGP with labels which overcomes this limitation.
-Waris

MPLS questions about tunnels

I have a question
If I have 2 MPLS tunnels as follows,
PE1 ------> PE2
PE1 ------> PE3
Which PE is the Ingress and Egress ?
I am getting asked this question with the same syntax in a practice exam. It doesn't specify whether TE tunnel or LSP.
Another question,
Why does show ip bgp neighbors on my PE not show my sessions with the RR unless I explicitly enter their IP addresses ?
If I do a show ip bgp neighbors I don't get anything. If I do show ip bgp neighbors 10.10.10.1 I will see the session.
So it means I have to look at the config to get the neighbor IP address first ?
That doesn't seem optimal..
Thanks
Darren

1) your PE 1 is the ingress and PE2 and PE3 are egress.
2) You should get the BGP and TCP info for all the adjacent neighbours if you use "show ip bgp neighbors". And to see the adjacent neighbors IP you dont have to see the configuration. You can issue simply " show ip bgp summ" and you will see the IP.
HTH-Cheers,
Swaroop

URGENT: QoS Design on Data Center MPLS - MediaNet Question...

Hello,
I am posting this in hopes I can get some guidance from anyone who has done this in the field. We have a large enterprise customer with 21 sites all around the world, they have Verizon MPLS and are experiencing QoS related issues on their WAN regarding Video/Voice. We have proposed remediating their network acccording to the Enterprise QoS SRND 3.3 and the new MediaNet SRND to account for Video and TP QoS (
http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND_40/QoSCampus_40.html )
Here is the problem/question that was proposed in our presales meeting and I honestly don't know where to look for an answer... I am not asking for anyone to design a solution for me, just merely point me in the right direction:
The Data Center has a ~40MB MPLS Connection ( full mesh ) into the cloud ( Verizon )
Site A has a 8MB connection
Site B has a 4MB connection
I know on the Service policy and the interfaces at SiteA and SiteB I can assign "Bandwidth xxxx" and use ~95% of the bandwidth to do queuing and shaping/policing ect. I am not concerned with SiteA and SiteB, that I think I can handle...
Question was posed from the customer, "How can we ensure at the DataCenter level the 40MB MPLS is "chopped" up so that only 8MB of the total speed goes to SiteA ALONG with an attached QoS policy designed for that specific site, as well as ensure only 4MB goes to SiteB with an attached QoS policy.
So I am looking for a way to allocate bandwith per site on the DC 40MB connection going into the cloud ( so that SiteB cannot use more than 4MB ) and attach a MediaNet specific QoS Service policy to that site. The customer does not have seperate MPLS circuits for each site, they all come into the DC on 40MB shared ethernet connection ( no VC, or dedicated circuits to other sites ).
Any thoughts on if this is possible?
Thanks!
Alex

This is an example I have seen and I hope that is useful to you.
Site A
Subnet: 172.16.1.0/24
Site B
Subnet:172.16.2.0/24
HeadOffice:
ip access-list extended Site_A
permit ip any 172.16.1.0 0.0.0.255
ip access-list extended Site_B
permit ip any 172.16.2.0 0.0.0.255
class-map match-any Site_A
match access-group name Site_A
class-map match-any Site_B
match access-group name Site_B
policy-map To_Spokes
class Site_A
shape average 8000000
service-policy Sub_Policy(Optional)
class Site_B
shape average 4000000
service-policy Sub_Policy(Optional)
class class-default
shape average 28000000
service-policy Sub_Policy(Optional)
Interface G0/0
Description To MPLS cloud
bandwidth 40000000
service-policy output To_Spokes
interface G0/1
Description To HeadOffice
bandwidth 40000000
service-policy output To_Spokes
It would be greatly appreciated if someone can correct this or improve it as I am still learning.
Please see the netflow graph from one of our routers using a similar policy as above.

Questions stemming from the unidirectional nature of MPLS LSP

After reading the following excerpt, I have some questions that I hope someone could clear up for me.
"An MPLS connection (LSP) is unidirectional—allowing data to flow in only one direction between two endpoints. Establishing two-way communications between endpoints requires a pair of LSPs to be established. Because 2 LSPs are required for connectivity, data flowing in the forward direction may use a different path from data flowing in the reverse direction."
Suppose I have a Network Management Station at each of the two geographically dispersed Data Centers, carrying out identical SNMP/ICMP-based monitoring against the same remote router at a third Data Center that's connected to the first two DCs via MPLS sold by the same ISP. There've been occasions when only one NMS (at say DC_A) reported the router at the third DC "down" (unreachable). Upon seeing the alert, the network operators sitting in DC_B pinged the remote router at DC_C successfully, therefore concluding the NMS was "crying wolf". I had thought it meant there's a problem with the particular MPLS circuit over there. But given the above paragraph about MPLS' unidirectionality, and the fact multiple interruptions in either forward or reverse direction could cause the NMS software to eventually conclude that the remote router has become unreachable, was my original conclusion wrong? What correct conclusions could be drawn from the aforementioned scenario of a single NMS reporting an outage at the other end of the MPLS? Furthermore, is it possible that actual business application traffic flowing through the same DC_A <=> DC_C MPLS could be unimpacted while my NMS there was alerting, due to the former taking a "different path"?

Hello Yjdabear,
your understanding is correct in line of principle one LSP can be broken and the NMS of site A complains of connectivity failure.
testing on path site A to site C can provide a different result then test from site B to site C
To be noted that there are some tests that could be run on routers to check the health state of LSPs
see
http://cco.cisco.com/en/US/docs/ios/12_4t/12_4t11/ht_lspng.html#wp1054520
so there are ways to understand if LSPs between site A and site C and between site B and site C are operational
Hope to help
Giuseppe

MPLS core questions

Hi,
I want to know the answers for the following failure scenario
1.Unknown LSP connectivity problem: LSP connectivity problem ,Data plan issue, or unknown cause
2.Distributed LFIB table discrepancy: There is a discrepancy in the LFIB table between the route processor and line cards
3.Distributed LFIB table discrepancy: There is a discrepancy in the FIB table between the route processor and line cards

hello dear mohisaxe,
so sorry for the late response, yes we plan to use them on separate ports and both CE and use the same line card as both customer and MPLS core facing.
just another quick question i have here:
1- as Mr. Xander's information, MOD80 line card has 2 typhoons each of them can accommodate 32K PPPOE sessions with limitation of 64K limit per line card.
2- as we have MOD160 line card with 4 typhoons, do we have the same limitation as above?
thanks for your support :)

MPLS provider Ethernet handoff question

Hi Everyone,
Here is what I am after from my ISP: I want MPLS with an Ethernet handoff, but do not want them to manage the router. I don't have to mess with bonding T1's or DS1's etc. due to past experience: It was always a battle of my WIC vs there smartjack being good or bad.
Here is my question:
These days, can providers typically hand off Ethernet so that I don't have to mess with bonding T1's or DS1's etc.?
Thanks,
Josh

Hi Josh
Yes now providers are changing towards Ethernet handoffs but some providers would make this decision on the bandwidth requirement per site, for obvious reasons.
Regards

MPLS network design questions

we have in our company 230 remote sites, and we are changing all of our circuits to MPLS. wondering if i need to get a high end router in our Data Center? currently we have 3925. also what is the best routing protocol to use in this kind of network? Eigrp or ospf? MPLS will be hosted by the service provider

I have found that the provider typically wants to know exactly what routes you will be advertising when using EIGRP or OSPF. This is something they will have to configure on their network to allow. For example EIGRP routes flow from Site A to Site B and you have a new subnet to use for an application. You put the proper network statements in EIGRP and are not learning routes on the other side. You would then have to fill out a form or call a support number to get your new network to the other side.
With BGP there is much more control over what you can advertise with adding networks. With 230 sites you will feel the benefit quickly if you start growing and adding subnets in data centers or additional sites.

#no mpls ip propagate-ttl cmd question-?

Hi:
When this cmd. is enabled both on PE1 and PE2 across a MPLS core, why does the trace output show the egress PE2 router in the output?
I have CE1->PE1->P->PE2->CE2.
I am tracing to the lo0 of CE2 10.1.8.8
PE1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
PE1(config)#no mpls ip propagate-ttl
PE1(config)#end
PE2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
PE2(config)#no mpls ip propagate-ttl
PE2(config)#end
CE1#tr ip 10.1.8.8
Type escape sequence to abort.
Tracing the route to 10.1.8.8
1 10.1.17.1 28 msec 28 msec 28 msec
2 10.1.58.5 168 msec 180 msec 168 msec
3 10.1.58.8 112 msec * 112 msec
CE1#
As you can see, 10.1.58.5 is the PE2 intf. to CE2. I was hoping to see only 2 hops.
Now the doc for this cmd does say that it sometimes shows the egress provider router.
Is this based on IOS or router model?
Or just another bug ;->
Thx.

Thanks Harold!!
I was going by the example shown in the pdf for MPLS Technology Essentials where they only showed 2 hops, the 1st PE and then CE2 and thus....(they did state that sometimes the egress PE would also show up)....

MPLS training question

Hey guys,
I took an MPLS course online and it pointed something out I really didn't get, or at least need clarification on.
The person giving the course said that because of how the PE's interact with the P LSR's that is isn't necessary to run a routing protocol in the core on the P's and that savings in resource is a reason to go to MPLS.
Can I get some clarification?
Do the P MPLS LSR's rely only on labels for routing or are they running a routing protocol in the background?
Thanks,
BR

Hi Brent,
Let me see if I can bring clarification.
The trainer said that running a routing protocol on the P routers was not necessary.
Let's have only a look at an MPLS VPN network, because that is what is referred to here, I think.
(Also, we only consider LDP and not TE as label distribution protocol.)
In that case, all PE and P routers need to run an IGP. When MPLS is deployed, MPLS still relies on
a routing protocol, which distributes the routes. LDP distributes the labels. LDP only assigns
labels to IGP routes in the routing table, hence an IGP is needed in the core. The routes from the
IGP and the labels from LDP are the two main ingredients needed to build the LFIB which is used
to forward the labeled packets.
Now, perhaps I know where the confusion comes from. I believe that in the training a hypothetical
alternate solution to MPLS VPN as we know it, was presented. Namely, that the VPN routes
could be distributed hop-by-hop from PE to P to PE routers by one IGP per VPN (and LDP
distributing the labels). This could be theoretically possible, but it would lead to scalability
issues because of the number of routing protocols. It also leads to an operational nightmare
for the people operating the MPLS network. Hence, that kind of MPLS VPN was never implemented.
I believe this could be the "savings in resource" that you mentioned.
In the real MPLS VPN solution, we run BGP between the PE routers which carry the VPN routes (and the VPN label),
hence the P routes do not need to run an IGP per VPN. They only need to run one IGP for the global routes.
BGP is not needed on the P routers.
Well, that's what I can come up with as an explanation. Anyway, you need to run an IGP on the P routers.
Thanks,
Luc.

MPLS design question

Hi all,
what is the best solution to extend a node (PE router) over a third party IP network.
Here is the scenario - there is a need to extend an MPLS network to a new location, but due to commercial/policy reason the only available options are a third part IP Network (non-MPLS) and a back haul wireless link. We are thinking of making the IP Network the primary link and the wireless back haul the back up links.
Is L2TPv3 the only solution? I want to make use of the wireless back haul also for some traffic.
Regards,
san

Hi Aasheesh,
The service provider will only give me a L3 connectivity. In this case the LDP session will not establish with my PE on both ends.
I tries GRE on my PE with LDP enabled and it seems to take the command, but i have to try this between two PE. so I am not sure if I can bring the tunnel up and allow the two PEs to exchange LDP. I was just hoping that i could find a doc on it so that I can be sure that it will work. If you know if any doc that would be great.
reagrds,
san

MPLS Central Service question

we have a few servers which are serving existing VoIP customers. we are planning to implement mpls central service on those servers. Can anyone recommend some method we can do this?

basicly u will need VRF for each customer
and one more VRF for central services here the VOIP service
and through the VRF/route-target values u need to make all customer VRFs being improted by VIOP VRF and each customer VRF must import the VOIP VRP/RT
if helpful Rate

MTU - MPLS DS3 Setup Question

I'm not sure if I am in the correct section.
We have an MPLS network with DS3s. From what I understand (and correct me if I am wrong), MPLS puts 4 bytes on the packet. Our serial has an MTU size of 4470. Our Ethernet has an MTU size of 1500.
Do I need to change the MTU size, and if so on which interface do I need to make this change. My thinking is to change it on the serial interface (MTU => 4466).
Am I right in my assumption?

Hi,
MPLS will add 4 bytes extra to the plain IP packet. Aplications of MPLS (MPLS-VPN, AToM, MPLS TE, MPLS QoS) will add stacks of labels to IP packet. So if you are running MPLS applications on your network then your Layer 2 MTU of the physical media should be capable of handling these extra stack of labels.
In your case since DS3 is having MTU of 4470 and most data packet comes from Ethernet, it is capable of carrying MPLS Labelled packets. You need to increase the MPLS MTU of your Ethernet media = Physical MTU + No. of Label stacks (depend on applications).. It is advisable to configure the MPLS MTU on ethernet interface to 1546 (1500 bytes + 46 bytes extra ...though it is more for basic MPLS, MPLS VPN considering the future development it will be better to keep the MPLS MTU to a higher value).
Note: MPLS MTU command is applicable only for the labelled packets. If any unlabelled packet with MTU more than of 1500 bytes is entering Ethernet interface then it ll get fragmented or dropped (depends on DF bit flag in IP header)
int ethernet0
mpls mtu 1546
HTH....

MPLS-TE : some question

Hi,
I'm studing for MPLS exam and after reading the documentation some aspects about MPLS-TE are still not clear .
I hope you can help me to clarify some concepts:
1)Is RSVP a requirement on every router link of the ISP when we are using dynamic tunnel computation considering that a tunnel could change his path?
2)Is Constrant-based routing(CBR)used when the tunnel is configured using an explicit path?

Hello Marco,
MPLS TE are unidirectional and also RSVP reservations are unidirectional.
Said this the answers are:
1) yes an alternate path can be used only if it has enough RSVP resources to satisfy the requests in the RSVP tunnel setup message.
resources are consumed outbound towards destination node
2) yes every possible path dynamic or explicit uses constrained based routing that means takes in account resources and resource current usage.
For this reason an MPLS TE with only a path option describing an explict path will fail if not enough resources are available on one of the specified links on the path
Hope to help
Giuseppe

TE in MPLS question

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