MPLS load balancing

Hello,
Graph of the network is in the attachment. I have problem that loadbalanicing among two GigabitEtehernet links in OSPF (between PE4 and P1 router on the picture)doesn't work. Black link goes to 1G/s and begins to drop packets and red one stays empty. Amount of traffic is 1,4Gbps. 700Mb/s from EoMPLS vlan 11 plus 700Mb/s from EoMPLS vlan 12.
Regarding two EoMPLS tunnels, PE4 should balance traffic in CEF and it should look the inner label from MPLS packet.
All routers are Cisco7600
Here is output from PE4
PE4#sh mpls forwarding-table 192.168.0.5 32 detail
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or VC or Tunnel Id Switched interface
395 134 192.168.0.5/32 1573173346488 Gi1/0/0 10.10.1.189
MAC/Encaps=14/18, MRU=9216, Label Stack{134}
001563F33EC0001C0F5C92C08847 00086000
No output feature configured
Per-destination load-sharing, slots: 0 2 4 6 8 10 12 14
134 192.168.0.5/32 130361493 Gi2/0/0 10.10.1.197
MAC/Encaps=14/18, MRU=9216, Label Stack{134}
001563F33EC0001C0F5C92C08847 00086000
No output feature configured
Per-destination load-sharing, slots: 1 3 5 7 9 11 13 15
PE4#sh mpls forwarding-table 192.168.0.105 32 detail
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or VC or Tunnel Id Switched interface
120 49 192.168.0.105/32 0 Gi1/0/0 10.10.1.189
MAC/Encaps=14/18, MRU=9216, Label Stack{49}
001563F33EC0001C0F5C92C08847 00031000
No output feature configured
Per-destination load-sharing, slots: 0 2 4 6 8 10 12 14
49 192.168.0.105/32 217252 Gi2/0/0 10.10.1.197
MAC/Encaps=14/18, MRU=9216, Label Stack{49}
001563F33EC0001C0F5C92C08847 00031000
No output feature configured
Per-destination load-sharing, slots: 1 3 5 7 9 11 13 15
If anyone have idea what could be the problem please give me a hint.

Hi,
Can you just clarify me which command I use on PE4 in order to see which outgoing interface uses EoMPLS VLAN11. For EoMPLS VLAN 12 I use show mpls l2transport vc 12, but I can't use this command for vlan12 because it originates on PE3. On PE4 EoMPLS vlan11 should be MPLS packet. So do I use show mpls forwarding-table 192.168.0.5 detail (or maybe show ip cef exact-route).
In the output below you can see both outgoing interfaces Gi1/0/0(black link) and Gi2/0/0(red). I can't see which one it uses.
PE4#sh mpls forwarding-table 192.168.0.5 32 detail
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or VC or Tunnel Id Switched interface
395 134 192.168.0.5/32 1573173346488 Gi1/0/0 10.10.1.189
MAC/Encaps=14/18, MRU=9216, Label Stack{134}
001563F33EC0001C0F5C92C08847 00086000
No output feature configured
Per-destination load-sharing, slots: 0 2 4 6 8 10 12 14
134 192.168.0.5/32 130361493 Gi2/0/0 10.10.1.197
MAC/Encaps=14/18, MRU=9216, Label Stack{134}
001563F33EC0001C0F5C92C08847 00086000
No output feature configured
Per-destination load-sharing, slots: 1 3 5 7 9 11 13 15
and for CEF otputs are:
PE4#sh ip cef exact-route 192.168.0.1 192.168.0.5
192.168.0.1 -> 192.168.0.5 => label 134 TAG adj out of GigabitEthernet1/0/0, addr 10.10.1.189
But since PE4 is Cisco7600 this command should be relevant and its output shows that Gi2/0/0 as ougoing interface(red link)
PE4#sh mls cef exact-route 192.168.0.1 192.168.0.5
Interface: Gi2/0/0, Next Hop: 10.10.1.197, Vlan: 1023, Destination Mac: 0015.63f3.3ec0

Similar Messages

MPLS Load Balancing/Sharing with TE or CEF or Both?

So I am just playing around in GNS3 trying to set up multiple ECMP links between to P routers like this;
CE1 -- PE1 -- P1 == P2 -- PE2 -- CE2
(There are actually four links between P1 & P2!)
I have set up a pseudoswire xconnect from PE1 to PE2 so CE1 & 2 can ping each other on the same local subnet range. That works just fine.
My question is this:
I have configured "ip load-sharing per-packet" on each of the four interfaces on P1 and P2 that are facing each other (I know per-packet balancing is frowned upon but lets not talk about that right now!) and this works, traffic is distributed across all links (I can see with packet captures in GNS3).
Where does "ip load-sharing per-packet" fit in to the chain of events with regards to MPLS and CEF etc?; So, with MPLS enabled everywhere the two P routers are forwarding based on labels and not IP address. With MPLS enabled, does this command force the P routers to load-balance each MPLS frame as it comes in, round-robbin'ing the ingress frames across all links, the same as it would if it were a plain IP packet? So the command is ignorate of the kind of traffic being used? Or is the P router looking down into the MPLS frame for the IP in the IP packet?
Also, in order to get the same sort of performance boost you get from per-packet load balancing, seeing as I am using MPLS here, should I be using some francy MPLE TE to do this instead of that interface sub-command?
If I remove that command, I seem to always use link 2 for sending traffic towards P2 from P1, and link 3 for receiving the return traffic from P2 to P1. This is presumably because the ICMP packets have nothing to hash on except the source and destination IP addresses, so they always hash to the same physical links. Without using that command how else can I make use of the four links?

Hello Jwbensley,
first of all,
"ip load-sharing per-packet" is not a viable option as it causes out of order issues.
Real world devices perform load balancing based on the second (more internal ) label value so to achieve some load balancing for example multiple pseudowires must be defined between the same pair of PE nodes.
L3 VPN use different internal labels for different customer prefixes of the same VRF site ( unless some special command is used to say use one label per VRF site)
>> f I remove that command, I seem to always use link 2 for sending traffic towards P2 from P1, and link 3 for receiving the return traffic from P2 to P1
This is the expected behaviour in this scenario.
With MPLS TE you can achieve results similar to the use of multiple pseudowires /LSPs : forms of load sharing not true load balancing. In all cases in MPLS world flow based and not per packet
Hope to help
Giuseppe

FR-MPLS load balancing

Hi All,
i hv 3 Fr circuits and 1 mpls circuits from india to Usa. is it possible that i will go fro load balancing? pls give me the solution
Thanks

Yes it possible depending on your routing protocol being used,
1) With BGP,Static being used on your PE-CE and as well as other FR links you can control the routing, and install four paths towards your other end destinations.
2) If you have OSPF then you will need help form your MPLS service provider to give you intra-area routes of the other side, as over MPLS VPN you will see the other side routes as Inter-Area routes and hence only your FR links would be preferred for load balancing exlcuding the MPLS VPN circuit.
HTH-Cheers,
Swaroop

MPLS TE equal or unequal load balancing doesn't work? - step2

Previous question in thread:
Dear Sir!
I've two MPLS TE tunnels from one PE to another PE.
And there are traffic share count between them
(as tunnel mpls traffic-eng load-share command define).
But in real life all traffic from the same source to the same destination go through only one tunnel
(as CEF define - i.e. how sh ip cef exact-route says).
PEs are 3660 platforms with c3660-jk9o3s-mz.123-8.T
installed.
How can I correct this problem?
But this answer does not solved my issue:
hritter - Network Consulting Engineer, CISCO SYSTEMS, CCIE
Aug 4, 2004, 7:20am PST
This is expected behavior since CEF is used at the head end to perform label imposition. I wouldn't recommend changing the default bahavior to per=packet loadsharing since this could lead to of of sequence packets, which could lower the overall performance.
Hope this helps,
so my secound question:
Dear Sir!
I'm agree with you as MPLS TE tunnels are opened from PE to PE, so CEF does it work.
But if I open this tunnels from P to PE, ONLY ONE of this tunnels are used instead of load-sharing, if traffic go from one source (of site1 of VPN1) to the same destination (located at site2 of VPN1).
Why? Packet through P-devices swithes by labels, so I mean that CEF cannot does src-dst load sharing?
My problem are that I must to do load sharing between this two tunnels in the case above.
Q: How can I solve this problem?
Best regards,
Maxim Denisov

The per session load-balancing is also used by MPLS when multiple paths are available. Changing this behavior to per-packet is still not recommended.
Hope this helps,

Load-balancing in MPLS Core

How is load-balancing achieved in MPLS L3 vpns and equal cost multiple links exist to reach egress PE along with per-destination load-balancing enabled on interfaces.
I have tried to simulate the network below
Ingress PE--->P1--->>P2--->Egress PE
Multiple equal cost links exist between P1 and P2, cisco platform,LDP, IGP-ospf being used.

Hi,
Destination based load balancing in MPLS L3VPNs can be categorized into two scenarios:
1) multiple pathes between two PE routers
2) multiple access links to a single CE or site
Your question as I understand it was about the first scenario. So let me first quickly review how customer traffic is forwarded between VRFs on two different PE routers.
The VRF routing table will have BGP entries for the routes learned from the remote PE usually with next hop addresses being the remote PE loopback IP used for PE-to-PE BGP peering.
The traffic will be forwarded across P routers using the label for the BGP next hop.
Thus the load balancing accross the MPLS core in a first step is decided by the IGP, which has to insert several equal cost pathes into the global routing table for the BGP next hop networks (PE loopbacks).
Side note: MPLS traffic engineering in the core would allow for unequal cost load balancing.
The decision, which labeled packet to send across which path in the core is done by CEF using a hash algorithm. To achieve the same load balancing as with unlabeled IP traffic, a Cisco MPLS enabled router will look for the bottom label - the one with bottom-of-stack bit set to 1 - and try to determine, if the transported packet behind the bottom label is IP. If so, the hash is calculated for the customer IP header like for normal IP traffic. This ensures all traffic for a certain customer destination will always go through the same path. No unwanted packet reordering will occur.
Be aware, that the customer IP packet header will only be used for CEF hash calculation, no IP lookup will be performed, as core routers in MPLS L3VPNs do not have any knowledge about customer addresses.
As a side note: if the traffic transported is not IP (e.g. Ethernet over MPLS), the bottom label will be used for the CEF load balancing (e.g. the VC label).
For the second scenario - CE load balancing with multihomed CE/sites - it is first required to have two equal cost entries in the VRF routing tables. The difference will be the two different PE BGP next hop addresses. The first load balancing decision is the performed by CEF based on the IP packet received by the CE and the VRF routing table entries. Once CEF decided, which VRF entry to use, the required BGP next hop label (and the VPN label) is applied and the packet is transported across the MPLS core. load balancing there is done as described above.
Hope this helps! Please rate all posts.
Regards, Martin

MPLS TE load-balancing --- CEF Problem

Dears
Would like your assistance please regarding below issue
We are having 5 TE tunnels going to same destination and we are doing load-balancing between these 5 LSPs TE tunnels.
Command "mls ip cef load-sharing full simple" is configured so that CEF will use L4 ports in its algorithm
Problem that due to CEF behavior, 2 link are v.highly utilized and the other 3 utilization are below average
What I am thinking of but not sure If this will help or not is to have 2 TE tunnels instead of 5
1 TE tunnel load balancing on 3 links ( This can be done by using static route to tail loopback poiting to the 3 links) and another TE tunnel load balancing on the other 2 links
By doing this, I think CEF would be used 2 times; first to determine which TE tunnel to use then to determine which link within the tunnel
Will this help ?
For example
interface Tunnel1
ip unnumbered Loopback0
mpls ip
tunnel destination 10.0.0.1
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng autoroute announce
tunnel mpls traffic-eng path-option 1 dynamic
tunnel mpls traffic-eng fast-reroute
ip route 10.0.0.1 255.255.255.255 link-1
ip route 10.0.0.1 255.255.255.255 link-2
ip route 10.0.0.1 255.255.255.255 link-3

Hello Sherif,
traffic of a single TE tunnel will not be load balanced over multiple physical links as the TE tunnel is setup using a reservation and the path will use only one link for each router hop.
So moving to two TE tunnels is not an option for you.
Hope to help
Giuseppe

MPLS/VPN network load balancing in the core

Hi,
I've an issue about cef based load-balancing in the MPLS core in MPLS/VPN environment. If you consider flow-based load balancing, the path (out interface) will be chosen based on source-destination IP address. What about in MPLS/VPN environment? The hash will be based on PE router src-dst loopback addresses, or vrf packet src-dst in P and PE router? The topology would be:
CE---PE===P===PE---CE
I'm interested in load balancing efficiency if I duplicate the link between P and PE routers.
Thank you for your help!
Gabor

Hi,
On the PE router you could set different types and 2 levels of load-balancing.
For instance, in case of a DUAL-homed site, subnet A prefix for VPN A could be advertised in the VPN by PE1 or PE2.
PE1 receives this prefix via eBGP session from CE1 and keep this route as best due to external state.
PE2 receives this prefix via eBGP session from CE2 and keep this route as best due to external state.
                             eBGP
                     PE1 ---------CE1
PE3----------P1                          Subnet A
                     PE2----------CE2 /
                            eBGP
Therefore from PE3 point of view, 2 routes are available assuming that IGP metric for PE3/PE1 is equal to PE3/PE2.
The a 1rst level of load-sharing can be achieve thanks to the maximum-paths ibgp number command.
2 MP-BGP routes are received on PE3:
PE3->PE1->CE1->subnet A
PE3->PE2->CE2->subnet A
To use both routes you must set the number at 2 at least : maximum-paths ibgp 2
But gess what, in the real world an MPLS backbone hardly garantee an equal IGP cost between 2 Egress PE for a given prefix.
So it is often necessary to ignore the IGP metric by adding the "unequal-cost" keyword: maximum-paths unequal-cost ibgp 2
By default the load-balancing is called "per-session": source and destination addresses are considered to choose the path and the outgoing interface avoiding reordering the packets on the target site. Overwise it is possible to use "per-packet" load-balancing.
Then a 2nd load-sharing level can occur.
For instance:
         __P1__PE1__CE1
PE3           \/                   Subnet A
        \ __P2__PE2__CE2
There is still 2 MP-BGP paths :
PE3->P1->PE1->CE1->subnet A
PE3->P1->PE2->CE2->subnet A
But this time for 2 MP-BGP paths 4 IGP path are available:
PE3->P1->PE1->CE1->subnet A
PE3->P1->PE2->CE2->subnet A
PE3->P2->PE1->CE1->subnet A
PE3->P2->PE2->CE2->subnet A
For a load-balancing to be active between those 4 paths, they must exist in the routing table thanks to the "maximum-path 4 "command in the IGP (ex OSPF) process.
Therefore if those 4 paths are equal-cost IGP paths then a 2nd level load-balancing is achieved. the default behabior is the same source destination mechanism to selected the "per-session" path as mentionned before.
On an LSP each LSR could use this feature.
BR

Load Balance with MPLS on a network with several links paralels

I have a question,...
Can you load balance on a network with mpls throght of several links with the same cost/metric?
Thanks!
Saul Barragan

O.k.
I dont know very well MPLS, neither VPN, but I know very well other type of protocols of IGP (like RIP,IGRP, EIGRP, OSPF) or EGP (like BGP), and I know how to balance the load by packets or by session, but I have this doubt and I want to know if its dificult or is the same but with something near/close-looks like it.
Can you tell me what does CE/TE Mean please.
Note: I know, I have to read a good book of MPLS.
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Saul Barragan

Load balancing over multiple E3s

Hi all,
For the same VP , can I make load balancing over multiple E3s connected bet the BPX 8600 and MGX 8850.
Asking the question in another way:
Is there a possibility for load balancing over multiple LSPs (multiple E3 interfaces) in Cell-Mode MPLS...and if possible,plz provide me with any good links for configuration.

Following link might be useful to you
http://www.cisco.com/univercd/cc/td/doc/product/wanbu/bpx8600/9_2/ref92/bpxrtag.htm

Load balancing with use of router 881.

Hello,
I have two MPLS line and i want load balancing with the help of CISCO router 881. is it necessary that i require two router on both location.? if one location have firewall and one location have cisco router 881 then can i do a load balancing or i require two router each on both location ? What are the basic requirement that i need.
Thanks,
Kuntal

Disclaimer
The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
Liability Disclaimer
In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
Posting
An 881 should be able to load share across multiple ports. Many routing protocol support ECMP, including BGP, but you need "special" hidden/secret commands to enable. EIGRP also supports unequal cost load sharing.
If an 881 supports OER or PfR, those too will do unequal load sharing, dynamically.

Load Balancing and Failover in Dual Ethernet

I have a cisco 2911/K9 router with two 4Mbps Leased line connection from two different ISPs to my remote office. Remote office has cisco 2811 router
Main office has MPLS connection with static Ip routing apart from the two leased lines
All handoffs are ethernet
Is it possible to do load sharing as well as fail over between the two ISPs, if so how am i to achieve that
Kindly help me

Disclaimer
The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
Liability Disclaimer
In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
Posting
If your MPLS vendor supports no dynamic routing, they why do you ask about BGP? Or, do they only support dynamic routing with BGP?
You can do equal cost multi-path with BGP (may require a hidden command to fully utilize).
You could do GRE tunnels across the MPLS cloud and dynamically route between them using your choice of a dynamic routing protocol.
Both your devices should support OER/PfR (may require a feature upgrade). OER/PfR will actually dynamically load balance.
SLA features should also be available on both your routers, those too might require a IOS feature upgrade.
Configuration examples might be found on Cisco's main web site.

Load-balancing in eompls

hy guys,
i read a previous post regarding how the
load-balancing is done for eompls.
someone says that the inner label (vc label) is responsable for this.
sincerely, if someone wants to explain me much deep how this works, it will be
very appreciate.
also, what is the meaning of the control word in the vc setup procedure ?

Load-balancing in the core is indeed based on the inner label (vc label) for EoMPLS.
So if the P router has many outbound interfaces for a given LSP, it will use that innner label to compute the hash value to select the outbound interface for that specific packet.
For an explanation on the control word please refer to the Martini encapsulation draft:
http://www.ietf.org/internet-drafts/draft-martini-l2circuit-encap-mpls-10.txt
Hope this helps,

Load Balance & redundancy for internet from 2 different sites?

Hi,
we have 2 core sites where our servers are situated. Both sites are connected via a ptp link.
All of our clients/sites reach these two sites via our MPLS network and they never route via the ptp link which is solely used between the two core sites.
One of the sites has an ASA which goes out to our internet. We are thinking of replicating this on our other site.
How would we go about load balancing the internet connection ie 50% go out on site A & 50% go out on site B?
And if site A goes down, everything goes out via site B and vice versa?
Diagram attached....
Thank you,
Louis

Hi Louis, you could set default routes on the ASA's with tracking, and use ospf downstream to inject the default route in to the network with default information originate - this will only advertise out a default route if it has it in the routing table. With SLA you can track internet reachability by IP SLA echo to something like 8.8.8.8. Both sides can advertise this in to the network, if one goes then there is one left. Just be mindful of the policies and NAT required, you will have to duplicate the rules on the ASA's. With the NAT you have to ensure, that outgoing traffic comes back in the same path it left so it doesn't break connections.

LOAD BALANCE BEHAVIOR FOR 7600 ON ETHERCHANNELS

Hi Everyone,
Currently I'm planning to implement ether-channels on 7600 routers, but there's something that's still not clear to me, regarding the load balancing behavior, for L2VPN and L3VPN.
I've read that 7600 in MPLS default load balance behavior is to take the SIP and DIP if present and the bottom of the stack label or the 5th label depending upon the number of labels on the stack. In l2VPN scenarios when ether-channel is used, if no IP traffic is present what is the default behavior of the etherchannel to calculate the load balancing hash function to select a given link on the bundle.
I'll appreciate any feedback regarding this.

Hi Louis, you could set default routes on the ASA's with tracking, and use ospf downstream to inject the default route in to the network with default information originate - this will only advertise out a default route if it has it in the routing table. With SLA you can track internet reachability by IP SLA echo to something like 8.8.8.8. Both sides can advertise this in to the network, if one goes then there is one left. Just be mindful of the policies and NAT required, you will have to duplicate the rules on the ASA's. With the NAT you have to ensure, that outgoing traffic comes back in the same path it left so it doesn't break connections.

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Dear Friends.......
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ISP 1 IP_172.16.10.1/24
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Plz explain with config,....
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Hi Alex
Sorry, I have 2 PRIs, PRI one is for main line & PRI two is for backup line, both should work as a load balancing... they are for placing voice calls to the PSTN ..
My concept is I have 3 routers... Router 1 is for PRI one, Router 2 is for PRI two & Router three is for load balancing...
Plz explain me how to config three router...
I hope In router one need to config with pri voice channels, In router two need to config with pri voice channels & In router three need to config load balancing...
Thanks & Regards,
Srinivas. N.

MPLS load balancing

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