Network Working Group Sudhin Jacob Internet Draft Juniper Networks Intended Status: Experimental March 24, 2014 Ethernet LDP( Label Distribution with out IP and routing protocols) draft-jacob-mpls-ethldp-00.txt Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." 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Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Abstract MPLS is the heart and soul of the service provider network. MPLS can carry anydata payload which gives the flexibility to the service provider to provision new service with any expense. The benefit of this technology is core router need not understand the full customer route. If the service a layer 2 then thereis no need of vrf, for customer the service provider cloud is like a virtual switch.The protocol used for label distribution is LDP, BGP,RSVP. The most popular protocol for outer label distribution is LDP. LDP has the benefit of adding more TLV to its payload. In this the possibility of using ldp for generating labels for mac address rather for ip address which gives the benefit to service provider not to run complex routing protocol on core, this does not require ip address. This gives service provider the flexibility to deploy any services, there is no need for changes in network layer when the customer goes for ipv4 to ipv6. This can reduce the CAPEX and OPEX of the customer and reduces the hardware cost too. Table of Contents 1.Introduction.....................................................3 2.Eth-ldp Problem Statement........................................4 3.How Eth-ldp will work............................................4 3.4 ETH-LDP for Customer Networks.................................7 3.5 ETH-LDP handling BUM from multihomed CE-----------------8 3.5 ETH-LDP Split Horizon label,Load balancing label---------10 4.1. Normative References-----------------------------------11 1.Introduction The current technologies require ip address to establish a label advertising protocol. This paper explains to have label adevertisement with out the ip address and routing protocol. This saves the configuration ,provisioning and trobleshooting time. In this there is no requirment of routing protocol to advertise the loopback address of the routers infact this have the cpablity to generate label per interface so this is very helpful in load balancing the traffic.Once this is configured on interface it will pick up the interface mac address and it will start communicating automatically with the help of interface mac address. Once the hello is exchanged between the two routers the adjacencies are formed. Once the adjacency is established then it can start exchange labels. The label mapping message will be exchanged to the neighbor router, it will generate labels for its entire connected interfaces. These labels will be generated for mac addresses instead of IP addresses. The labels are generated for mac address instead of IP address there will be changes in the normal ldp TLV. This can reduce the overall cost of operation and maintenance. The benefit is we can extend the label switching to metro ring and remove the complex configurations and vlan tagging. 2. Problem Statement There are different transport mechansim to carry customer data which requires IP address, Eth-LDP addresses the fact that the data from a layer 2 network from one geographical location to another can be transported to another using mac ldp which is simpler reduces the overhead to the Service provider and gives the customer more flexiblity to control the network. 3.How ETH-LDP will work Router A----------------------Router B------------------Router C Example: 1 Consider three routers A, B and C the interfaces are connected. There are no other protocols configured in these routers. Once we enable Ethernet LDP over the interface, it sends hello message, once hello message is received from the neighbor router both the routers receives from the neighbor router the adjacency is established. Once the adjacency is established, it sends label mapping message with labels for the connected interface and labels received from the other routers. Once the router gets the label after processing it updates the LIB so the router A knows the label to reach router C and vice versa. For example Router C advertise label 20 for its connected mac address it sends to Router B and router B sends label 21 for its connected mac address as well for the mac address of other routers reachable via router B to router A. Router A sends label 23 for its connected interface to router B and the router B sends label 24 to router C for its connected interface and mac address of other routers reachable through B to router C.When the data packet arrives at router A destined to router B, the label 21 is pushed by router A and send to router B. In router B the label swap operation is performed, router B knows once it gets a packet with label 20 it has to swap operation with label 21 and forwards the packet to to router C. The same operation is performed when the return packet goes from router C to router A. Router C pushes label 24 sends to router B and it swaps label with 23 and sends it to A. 3.1 ETH-LDP Hellos and Adjacency formations ETH-LDP Hello TLV 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Version | PDU Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LDP Identifier | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U|F| Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Value | ~ ~ | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Here the header will version will be 1; ldp identifier will be the mac address of the router or configured ID for identifying the router.The hello TLV consist of hold timer,flags, etc the transport address is removed from this because the communication is based on the mac address. The router will send hello at the configured hold interval divided by 3. The router is not receiving hello it will mark the neighbor down once the hold time is expired. The adjacency is lost all the labels learned from the peer will be flushed. The format of the hello message is same like ipv4 ldp but certain fields are modified to carry out the operation. The hello message id is same 0x100. 3.2 ETH-LDP Label Advertisements +-----------+ +------------+ | | | | | | | | | A |--------------------------- | | | | B | | | | | +--|--------+ | | | -- +-----|------+ | -- --- | | -- --- | | -- -- | | -- --- | | +---------------+ | | | | | | | | | | | C | | | | | | | | | | | +---------------+ | | -- -- | | --- -- | | -- --- | | --- -- | | -- -- | +---|--------------+ +-----------|----+ | | | | | | | | | D ---------------- | | | | E | | | | | | | | | +------------------+ +----------------+ Since we are not using routing protocol for label advertisements so routers dont have any idea for preventing loops because for the same mac address it receives labels from multiple sources. In order to avoid this scenario the label advertisement message must carry labels along with hop count (distance) so the router receives multiple labels from routers it will select only the lowest hop count (distance). It will not accept the labels for itself from others. The label must be generated for per platform basis. For example Router D generates label for its connected mac address to Router A and it advertises the same to router C and router B, router C and B advertises about router D labels to router A along with hop count when router A compares the labels received for router D mac address from Router B,D and C. Router A sees labels for reaching router D is lowest from router D so it takes labels for destination in router D from router D because of its lowest hop count. This prevents the loops. The other two details are cached in times of failure that can be used. The behavior is different when there is multiple links from same router there remote mac address will have multiple labels based on links and it will load balance based on different labels. 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0|0| Hop Count | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | HC Value | +-+-+-+-+-+-+-+-+ 3.3 ETH-LDP Label Withdrawal When the link is down the ETH-LDP sends a withdrawal message to withdraw the mac addess and the label ascociated to it for the remote PE router.Then the label will be flushed from the label database. 3.4 ETH-LDP for Customer Networks The PE routers which are connected to service provider can converged using above mentioned mechanism. When the customer wants to be connected the service provider msut know what all edge routers the customer traffic must be dropped. CE1--------PE1 --------------P---------------------PE2--------CE3 CE2---------PE1 Consider the above network customer A is multihomed and he wants to connect to remote site located at PE2, the service provider will make a connection to remote PE2 from PE1 and viceversa from PE2 to PE1. Once that is done the PE1 will generate a labels for BUM traffic,for unicast mac address,PE2 will generate the same for customer A. When the traffic comes CE1 the PE1 will put the BUM label then PE1 will put the outer label and forward the packet so once the packet reaches PE2 the label look up is done based on the inner label the packet is put in the correct instances. 3.5 ETH-LDP handling BUM from multihomed CE When the BUM traffic is orginated from one of the multihomed CE, it will not send the traffic back based on split horizon.When it is multihoming to different PE,one of PE will be elected as forwarder for this while configuring the PE's who all are in multihoming there must be a TLV which shows it is multihoming. So PE's sends targetted ETH-LDP with multihoming flag set.so based on the PE the PE with highest mac address is elected as DF, or there we can set priority to select the DF so that we can control the forwarder election, the default priority is 1.First it will check the highest priority, if there is a tie then it will select the highest mac address. The DF will forward the BUM traffic. Once DF is elected it will send split horizon label to other non DF router to send BUM traffic, if the BUM traffic is comming to non DF routers it will drop the traffic. Once the BUM traffic is coming to DF with split horizon label it will drop that traffic to avoid loops. the DF will send loadbalancing labels to all routers excpet the multihoming PE's this way it will load balance the traffic. 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0|0| Flags | priority | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | HC Value | +-+-+-+-+-+-+-+-+ 3.5 ETH-LDP Split Horizon label,Load balancing label The above labels will be generated for multihoming PE's once the DF is elected, DF will send split horizon label label to non DF's. This is used to prevent blocking BUM traffic sending back to the multihomed site. Once the BUM traffic recieved from attached CE's to non DF PE's it will use split horizon label to send it to DF PE's, it will add the BUM label,split horizon label and outer label to reach to remote PE. Once it reaches the DF PE it sees the split horizon label, it will drop the traffic.The load balancing label will be used to load balancing the traffic from remote PE's to multihoming PE's. This labels will be advertised by DF to remote PE's so it will use to load balance the traffic from remote PE to multihoming PE's References 4.1. Normative References [RFC5036] LDP Psecifications L. Andersson, Ed. Author Addresses Sudhin Jacob Bangalore, India Email: sudhinjacob@rediffmail.com