7-3 - Refresh on Traditional E-LAN, E-Line, and E-Tree Solutions Flashcards
Describe E-LINE.
- Also referred to as a Virtual Private Wire Service (VPWS, according to IETF naming conventions)
- a point-to-point service that connects two customer Ethernet ports over a WAN
- Further subdivides into:
*Ethernet Private Line (EPL) - uses a point-to-point EVC between two UNIs
*Ethernet Virtual Private Line (EVPL) - similar to EPL, but allows service multiplexing at the UNI to support more than one EVC
*Ethernet Internet Access (EIA) - dedicated Internet-access solution
Describe E-LAN.
- Also referred to as a Virtual Private LAN Service (VPLS, according to IETF naming conventions)
- multipoint service that connects a set of customer endpoints, which appears to the customer as a bridged Ethernet network that connects the sites.
Describe E-Tree.
- A point-to-multipoint service that connects one or more roots and a set of leaves yet prevents interleaf communication.
- This service is also known as rooted multipoint.
T/F: You can implement E-Line, also referred to as VPWS, by using Layer 2 Transport Protocol version 3 (L2TPv3) in an IP environment or AToM when you deploy it in an MPLS core.
True
T/F: VPWS is a point-to-point technology and involves MAC-learning capabilities.
False. VPWS is a point-to-point technology and involves no MAC-learning capabilities.
T/F: L2TPv3 provides several enhancements to L2TP to tunnel any Layer 2 payload over L2TP. Specifically, L2TPv3 defines the L2TP protocol for tunneling Layer 2 payloads over an IP core network by using Layer 2 VPNs.
True
T/F: IP core transport uses L2TPv3 and supports only point-to-point connections.
True
Describe Cisco Any Transport over MPLS (Cisco AToM).
- a solution for encapsulating and transporting Layer 2 frames over an MPLS backbone.
The two AToM interworking modes are the following:
- Bridged interworking mode:
*Ethernet frames extract from the attachment circuit and transmit over the PW. Non-Ethernet attachment circuit frames drop.
*Command: interworking ethernet
Under PW class subconfig mode - Routed interworking mode:
*IP packets extract from the attachment circuit and transmit over the PW. Attachment circuit frames drop if they do not contain the IPv4 packets.
*Command: interworking ip
Under PW class subconfig mode
Describe Ethernet over MPLS (EoMPLS).
- Ethernet over MPLS (EoMPLS) is the most common AToM type. Ethernet-over-MPLS allows you to send Layer 2 Ethernet frames transparently over MPLS.
- It encapsulates Ethernet protocol data units (PDUs) inside MPLS packets and forwards the packets, using label stacking, across the MPLS network.
- You can connect two Layer 2 networks that are in different locations, without requiring routers or any other Layer 3 device for interconnection.
T/F: In Cisco IOS XR Software, you must enable the attachment circuit for Layer 2 transport by using the l2transport keyword.
True
When the VLAN tags rewrite in an EoMPLS service, the customer switches will report these Syslog messages:
%SPANTREE-2-RECV_PVID_ERR: Received BPDU with inconsistent peer vlan id 12 onGigabitEthernet0/0 VLAN21.
%SPANTREE-2-BLOCK_PVID_LOCAL: Blocking GigabitEthernet0/0 on VLAN21. Inconsistent local vlan.
You can block the BPDU in two ways:
- BPDU filter on switches
*Command (IOS-XE): spanning-tree bpdufilter enable interface - Block PVST+ BPDUs on the PE router
*you can filter the PVST+ BPDUs with the Layer 2 ethernet-services access-list
*Ex:
ethernet-services access-list filter-stp
10 deny any host 0100.0ccc.cccd
20 permit any any
Which of the following statements is true?
A. You can implement E-Line, or VPWS, with L2TPv3 in an IP environment or with AToM in an MPLS core.
B. E-LAN, or VPLS, offers point-to-multipoint and multipoint-to-multipoint connectivity in an IP environment.
C. AToM is the most common type of Ethernet over MPLS.
D. The EoMPLS configuration on Cisco IOS XR platforms is the same as for Cisco IOS XE platforms.
A
