Organization of a hybrid port on the Alcatel-Lucent 7210 SAS-M

Recently, a business operating in our Homeland in the conditions of the toughest competition finally remembered a client with all the ensuing consequences for the latter. The word "customer-oriented" and our organization did not bypass the new-fashioned word in the language of the Russian capitalists. We were tasked to provide the client with the best possible and reliable service. Along with network optimization, projects have been opened to work out backup channels for important areas.

Most of the main channels have long been implemented on the basis of fiber optic lines and the backup channel for these sections should be of appropriate capacity so that in the event of an accident at the main section, the favorite customers do not feel anything. It is simply unrealistic to build fiber-optic lines at some sites because of the impossibility of obtaining technical specifications from state monopolies (RZD, Gazprom and others), or would cost a space sum, so a solution based on an E-band radar from the well-known company NEC was chosen to reserve the site. RRL provides a channel with a capacity of 1Gbps at a distance of 5 km.

The IP / MPLS core network is implemented on Alcatel-Lucent equipment (7750SR and 7210 SAS-M) and this equipment has the ability to switch traffic routes based on FRR technology and BFD protocol. The switching time is less than 50 ms, which is quite enough to maintain the continuous operation of the packet data services. As a result, the reservation scheme took the following form:


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REC NEC iPasolink E-BAND is a fully outdoor construction and management can be organized in two ways:

1. out-band. At the same time, it is required to release a separate UTP cable from the active unit on the antenna support and plug it into some equipment in the equipment room (this can be done on the same alcatel 7210).
2. in-band. The control channel can be started up in the same physical medium with traffic channels, i.e. using existing fiber going upstairs.

Method 2 is cheaper, more reliable, easier to operate, so the choice was made on it. And here we are faced with the following problem. To implement the idea of ​​automatic backup and use all the advantages of FRR and BFD ports on MBH1 and MBH2 in the direction of the RRL should be configured in the "network" mode, and this does not allow to handle the control traffic of the RRL, which for the Alcatel-Lucent MPLS network is user and for it (traffic) the port must be configured in the “access” mode.
The version of the TiMOS-B-5.0.R9 OS used does not allow implementing a hybrid port, so I had to think. The following scheme came to mind:



A few explanations to the scheme on the example of the MBH1 switch. Interfaces of the butt network organized through RRL “hang” tag 299 on ethernet frames. All MPLS chips are encapsulated inside an ethernet frame, so a packet RRL operating at the L2 level with VLAN support (IEEE 802.1Q) switches these frames and transmits to remote terminal, which in turn switches, transferring frames from the radio link to the optical link. At the same time, the IN-BAND control channel of the RRL with another tag, VLAN 22, is switched to the optical link. As a result, two virtual networks are terminated on one physical port MBH1 p1. The port is configured in access mode:

port 1/1/1 description "1GE-1/1/1-to-NEC_E_BAND" ethernet mode access access exit encap-type dot1q mtu 9212 ssm no shutdown exit exit no shutdown exit 

On the 7210, two VPLS for MPLS and VPLS for management NEC services are configured. Each service has a service access point (literally an access point to the service) and based on the VLAN 299 tag and VLAN 22 each “get” into their own VPLS (VPLS is essentially a virtual switchboard organized onboard 7210). VPLS for MPLS via sap 1/1/2: ​​299 “passes” frames with MPLS fields to the port of the p23 switch, which is associated with the butt-interface interface “if-MBH2”. Port port 1/1/2 is configured in access mode, and port 1/1/23 is already configured in network mode:

 port 1/1/2 description "1GE-1/1/2-to-1GE-1/1/23" ethernet mode access access exit encap-type dot1q mtu 9212 exit no shutdown exit port 1/1/23 description "1GE-1/1/23-to-1/1/2" ethernet encap-type dot1q network exit ssm no shutdown exit exit no shutdown exit 

The NEC RRL management service can be brought out via some sap on the same switch, or launched via the MPLS network via the spoke-sdp service tunnel to the management gateway.

Add configuration for MBH1.

1. Interface:

 router interface "if-MBH2" address 192.168.1.33/30 port 1/1/23:299 bfd 100 receive 100 multiplier 3 exit 

Setting up BFD in this case is necessary so that the interfaces of the network organized through the RRL ask each other over a certain time interval and, if there is no connection through the RRL, traffic was initiated to the backup route. The FRR technology in this case will not work correctly, because if the RRL link is broken (due to the weather, for example, although icebergs from pipes fall the size of an old tube TV, damaging everything in its path) the ports connected to the switch's network ports will be in the up status, and the link connectivity between the switches is broken . But more about this in the following articles.

2. VPLS services (in my case epipe is configured):

  epipe 9024 customer 7 svc-sap-type any create description "Gibrid_Port_7210_MPLS" service-mtu 9194 service-name "Gibrid_Port_7210" sap 1/1/1:299 create description "MPLS_over_E-BAND" exit sap 1/1/2:299 create description "MPLS_to_7210_MBH1" exit no shutdown exit epipe 9025 customer 7 svc-sap-type any create description "Gibrid_Port_7210_NEC_MGMT" service-mtu 9160 sap 1/1/1:22 create description "NEC_MGMT_IN" exit sap 1/1/3:22 create description "NEC_MGMT_OUT" exit no shutdown exit 

In principle, everything. Waiting for comments and criticism.

Thanks for attention.