| BESS Workgroup | P. Jain, Ed. |
| Internet-Draft | S. Salam |
| Intended status: Standards Track | A. Sajassi |
| Expires: November 23, 2019 | Cisco Systems, Inc. |
| S. Boutros | |
| VmWare, Inc. | |
| G. Mirsky | |
| ZTE Corporation. | |
| May 22, 2019 |
LSP-Ping Mechanisms for EVPN and PBB-EVPN
draft-ietf-bess-evpn-lsp-ping-00
LSP-Ping is a widely deployed Operation, Administration, and Maintenance (OAM) mechanism in MPLS networks. This document describes mechanisms for detecting data-plane failures using LSP Ping in MPLS based EVPN and PBB-EVPN networks.
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This Internet-Draft will expire on November 23, 2019.
Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved.
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[RFC7432] describes MPLS based Ethernet VPN (EVPN) technology. An EVPN comprises CE(s) connected to PE(s). The PEs provide layer 2 EVPN among the CE(s) over the MPLS core infrastructure. In EVPN networks, PEs advertise the MAC addresses learned from the locally connected CE(s), along with MPLS Label, to remote PE(s) in the control plane using multi-protocol BGP. EVPN enables multi-homing of CE(s) connected to multiple PEs and load balancing of traffic to and from multi-homed CE(s).
[RFC7623] describes the use of Provider Backbone Bridging [802.1ah] with EVPN. PBB-EVPN maintains the C-MAC learning in data plane and only advertises Provider Backbone MAC (B-MAC) addresses in control plane using BGP.
Procedures for simple and efficient mechanisms to detect data-plane failures using LSP Ping in MPLS network are well defined in [RFC8029][RFC6425]. This document defines procedures to detect data- plane failures using LSP Ping in MPLS networks deploying EVPN and PBB-EVPN. This draft defines 4 new Sub-TLVs for Target FEC Stack TLV with the purpose of identifying the FEC on the Peer PE.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].
AD: Auto Discovery
B-MAC: Backbone MAC Address
CE: Customer Edge Device
C-MAC: Customer MAC Address
DF: Designated Forwarder
ESI: Ethernet Segment Identifier
EVI: EVPN Instance Identifier that globally identifies the EVPN Instance
EVPN: Ethernet Virtual Private Network
MPLS-OAM: MPLS Operations, Administration, and Maintenance
P2MP: Point-to-Multipoint
PBB: Provider Backbone Bridge
PE: Provider Edge Device
This document introduces four new Target FEC Stack sub-TLVs that are included in the LSP-Ping Echo Request packet sent for detecting faults in data-plane connectivity in EVPN and PBB-EVPN networks. These Target FEC Stack sub-TLVs are described next.
The EVPN MAC sub-TLV is used to identify the MAC for an EVI under test at a peer PE.
The EVPN MAC sub-TLV fields are derived from the MAC/IP advertisement route defined in [RFC7432] Section 7.2 and have the format as shown in Figure 1. This TLV is included in the Echo Request sent to the Peer PE by the PE that is the originator of the request.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Distinguisher |
| (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Tag ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Segment Identifier |
| (10 octets) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | must be zero | MAC Addr Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address |
+ (6 Octets) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Must be zero | IP Addr Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Address (0, 4 or 16 Octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: EVPN MAC sub-TLV format
The LSP Ping echo request is sent using the EVPN MPLS label(s) associated with the MAC route announced by a remote PE and the MPLS transport label(s) to reach the remote PE.
The EVPN Inclusive Multicast sub-TLV fields are based on the EVPN Inclusive Multicast route defined in [RFC7432] Section 7.3.
The EVPN Inclusive Multicast sub-TLV has the format as shown in Figure 2. This TLV is included in the echo request sent to the EVPN peer PE by the originator of request to verify the multicast connectivity state on the peer PE(s) in EVPN and PBB-EVPN.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Distinguisher |
| (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Tag ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Addr Len | |
+-+-+-+-+-+-+-+ |
~ Originating Router's IP Addr ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: EVPN Inclusive Multicast sub-TLV format
Broadcast, multicast, and unknown unicast traffic can be sent using ingress replication or P2MP P-tree in EVPN and PBB-EVPN network. In case of ingress replication, the Echo Request is sent using a label stack of [Transport label, Inclusive Multicast label] to each remote PE participating in EVPN or PBB-EVPN. The inclusive multicast label is the downstream assigned label announced by the remote PE to which the Echo Request is being sent. The Inclusive Multicast label is the inner label in the MPLS label stack.
When using P2MP P-tree in EVPN or PBB-EVPN, the Echo Request is sent using P2MP P-tree transport label for inclusive P-tree arrangement or using a label stack of [P2MP P-tree transport label, upstream assigned EVPN Inclusive Multicast label] for the aggregate inclusive P2MP P-tree arrangement as described in Section 6.
In case of EVPN, an additional, EVPN Auto-Discovery sub-TLV and ESI MPLS label as the bottom label, may also be included in the Echo Request as is described in Section 6.
The EVPN Auto-Discovery (AD) sub-TLV fields are based on the Ethernet AD route advertisement defined in [RFC7432] Section 7.1. EVPN AD sub-TLV applies to only EVPN.
The EVPN AD sub-TLV has the format shown in Figure 3.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Distinguisher |
| (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Tag ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Segment Identifier |
| (10 octets) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | must be zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: EVPN Auto-Discovery sub-TLV format
The EVPN IP Prefix sub-TLV is used to identify the IP Prefix for an EVI under test at a peer PE.
The EVPN IP Prefix sub-TLV fields are derived from the IP Prefix Route (RT-5) advertisement defined in [I-D.ietf-bess-evpn-prefix-advertisement] and has the format as shown in Figure 4. This TLV is included in the Echo Request sent to the Peer PE by the PE that is the originator of the request.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Distinguisher |
| (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Tag ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Segment Identifier |
| (10 octets) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | must be zero | IP Prefix Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ IP Prefix (4 or 16 Octets) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ GW IP Address (4 or 16 Octets) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: EVPN IP Prefix sub-TLV format
The LSP Ping echo request is sent using the EVPN MPLS label(s) associated with the IP Prefix route announced by a remote PE and the MPLS transport label(s) to reach the remote PE.
The LSP Ping Echo request IPv4/UDP packets are encapsulated with the Transport and EVPN Label(s) followed by the Generic Associated Channel Label (GAL) [RFC6426] which is the bottom most label. The GAL label is followed by IPv4(0x0021) or IPv6(0x0057) Associated Channel Header (ACH) [RFC4385].
Figure 5 is an example of a PBB-EVPN network. CE1 is dual-homed to PE1 and PE2. Assume, PE1 announced a MAC route with RD 1.1.1.1:00 and B-MAC 00aa.00bb.00cc and with MPLS label 16001 for EVI 10. Similarly, PE2 announced a MAC route with RD 2.2.2.2:00 and B-MAC 00aa.00bb.00cc and with MPLS label 16002.
On PE3, when an operator performs a connectivity check for the B-MAC address 00aa.00bb.00cc on PE1, the operator initiates an LSP Ping request with the target FEC stack TLV containing EVPN MAC sub-TLV in the Echo Request packet. The Echo Request packet is sent with the {Transport Label(s) to reach PE1 + EVPN Label = 16001 + GAL} MPLS label stack and IP ACH Channel header. Once the echo request packet reaches PE1, PE1 will use the GAL label and the IP ACH Channel header to determine that the packet is IPv4 OAM Packet. The PE1 will process the packet and perform checks for the EVPN MAC sub-TLV present in the Target FEC Stack TLV as described in Section 4.4 in [RFC8029] and respond according to [RFC8029] processing rules.
BEB +-----------------+ BEB
|| | | ||
\/ | | \/
+----+ AC1 +-----+ +-----+ +----+
| CE1|------| | | PE 3|-----| CE2|
+----+\ | PE1 | IP/MPLS | | +----+
\ +-----+ Network +-----+
\ | |
AC2\ +-----+ |
\ | | |
\| PE2 | |
+-----+ |
/\ | |
|| +-----------------+
BEB
<-802.1Q-> <------PBB over MPLS------> <-802.1Q->
Figure 5: PBB EVPN network
Similarly, on PE3, when an operator performs a connectivity check for the B-MAC address 00aa.00bb.00cc on PE2, the operator initiates an LSP Ping request with the target FEC stack TLV containing EVPN MAC sub-TLV in the echo request packet. The echo request packet is sent with the {MPLS transport Label(s) to reach PE2 + EVPN Label = 16002 + GAL} MPLS label stack and IP ACH Channel header.
LSP Ping operation for unicast data-plane connectivity checks in E- VPN, are similar to those described above for PBB-EVPN except that the checks are for C-MAC addresses instead of B-MAC addresses.
Assume PE1 announced an Inclusive Multicast route for EVI 10, with RD 1.1.1.1:00, Ethernet Tag (ISID 10), PMSI tunnel attribute Tunnel type set to ingress replication and downstream assigned inclusive multicast MPLS label 17001. Similarly, PE2 announced an Inclusive Multicast route for EVI 10, with RD 2.2.2.2:00, Ethernet Tag (ISID 10), PMSI tunnel attribute Tunnel type set to ingress replication and downstream assigned inclusive multicast MPLS label 17002.
Given CE1 is dual-homed to PE1 and PE2, assume that PE1 is the DF for ISID 10 for the port corresponding to the ESI 11aa.22bb.33cc. 44dd.5500.
When an operator at PE3 initiates a connectivity check for the inclusive multicast on PE1, the operator initiates an LSP Ping request with the target FEC stack TLV containing EVPN Inclusive Multicast sub-TLV in the Echo Request packet. The Echo Request packet is sent with the {Transport Label(s) to reach PE1 + EVPN Incl. Multicast Label = 17001 + GAL} MPLS label stack and IP ACH Channel header. Once the echo request packet reaches PE1, PE1 will use the GAL label and the IP ACH Channel header to determine that the packet is IPv4 OAM Packet. The packet will have EVPN Inclusive multicast label. PE1 will process the packet and perform checks for the EVPN Inclusive Multicast sub-TLV present in the Target FEC Stack TLV as described in Section 4.4 in [RFC8029] and respond according to [RFC8029] processing rules.
An operator at PE3, may similarly also initiate an LSP Ping to PE2 with the target FEC stack TLV containing EVPN Inclusive Multicast sub- TLV in the echo request packet. The echo request packet is sent with the {transport Label(s) to reach PE2 + EVPN Incl. Multicast Label = 17002 + GAL} MPLS label stack and IP ACH Channel header. Once the echo request packet reaches PE2, PE2 will use the GAL label and the IP ACH Channel header to determine that the packet is IPv4 OAM Packet. Since PE2 is not the DF for ISID 10 for the port corresponding to the ESI value in the Inclusive Multicast sub- TLV in the Echo Request, PE2 will reply with the special code indicating that FEC exists on the router and the behavior is to drop the packet because of not DF as described in Section 8.
In case of EVPN, in the Echo Request packet, an Ethernet AD sub-TLV and the associated MPLS Split Horizon Label above the GAL label in the MPLS label stack, may be added to emulate traffic coming from a MH site, this label is used by leaf PE(s) attached to the same MH site not to forward packets back to the MH site. If the behavior on a leaf PE is to drop the packet because of Split Horizon filtering, the PE2 will reply with the special code indicating that FEC exists on the router and the behavior is to drop the packet because of Split Horizon Filtering as described in Section 8.
Both inclusive P-Tree and aggregate inclusive P-tree can be used in EVPN or PBB-EVPN networks.
When using an inclusive P-tree arrangement, p2mp p-tree transport label itself is used to identify the L2 service associated with the Inclusive Multicast Route, this L2 service could be a customer Bridge, or a Provider Backbone Bridge.
For an Inclusive P-tree arrangement, when an operator performs a connectivity check for the multicast L2 service, the operator initiates an LSP Ping request with the target FEC stack TLV containing EVPN Inclusive Multicast sub-TLV in the echo request packet. The echo request packet is sent over P2MP LSP with the {P2MP P-tree label, GAL} MPLS label stack and IP ACH Channel header.
When using Aggregate Inclusive P-tree, a PE announces an upstream assigned MPLS label along with the P-tree ID, in that case both the p2mp p-tree MPLS transport label and the upstream MPLS label can be used to identify the L2 service.
For an Aggregate Inclusive P-tree arrangement, when an operator performs a connectivity check for the multicast L2 service, the operator initiates an LSP Ping request with the target FEC stack TLV containing EVPN Inclusive Multicast sub-TLV in the echo request packet. The echo request packet is sent over P2MP LSP using the IP-ACH Control channel with the {P2MP P-tree label, EVPN Upstream assigned Multicast Label, GAL} MPLS label stack and IP ACH Channel header.
The Leaf PE(s) of the p2mp tree will process the packet and perform checks for the EVPN Inclusive Multicast sub-TLV present in the Target FEC Stack TLV as described in Section 4.4 in [RFC8029] and respond according to [RFC8029] processing rules. A PE that is not the DF for the EVI on the ESI in the Inclusive Multicast sub-TLV, will reply with a special code indicating that FEC exists on the router and the behavior is to drop the packet because of not DF as described in Section 8.
In case of EVPN, in the Echo Request packet, an Ethernet AD sub-TLV and the associated MPLS Split Horizon Label above the GAL Label in MPLS label stack, may be added to emulate traffic coming from a MH site, this label is used by leaf PE(s) attached to the same MH site not to forward packets back to the MH site. If the behavior on a leaf PE is to drop the packet because of Split Horizon filtering, the PE2 will reply with special code indicating that FEC exists on the router and the behavior is to drop the packet because of Split Horizon Filtering as described in Section 8.
The procedures described in [RFC6425] for preventing congestion of Echo Responses (Echo Jitter TLV) and limiting the echo reply to a single egress node (Node Address P2MP Responder Identifier TLV) can be applied to LSP Ping in PBB EVPN and EVPN when using P2MP P-trees for broadcast, multicast, and unknown unicast traffic.
Assume PE1 announced an Ethernet Auto discovery Route with the ESI set to CE1 system ID and MPLS label 19001, and PE2 an Ethernet Auto discovery Route with the ESI set to CE1 system ID and MPLS label 19002.
When an operator performs at PE3 a connectivity check for the aliasing aspect of the Ethernet AD route to PE1, the operator initiates an LSP Ping request with the target FEC stack TLV containing EVPN Ethernet AD sub-TLV in the echo request packet. The echo request packet is sent with the {Transport label(s) to reach PE1 + EVPN Ethernet AD Label 19001 + GAL} MPLS label stack and IP ACH Channel header.
When PE1 receives the packet it will process the packet and perform checks for the EVPN Ethernet AD sub-TLV present in the Target FEC Stack TLV as described in Section 4.4 in [RFC8029] and respond according to [RFC8029] processing rules.
Assume PE1 in Figure 5, announced an IP Prefix Route (RT-5) with an IP prefix reachable behind CE1 and MPLS label 20001. When an operator on PE3 performs a connectivity check for the IP prefix on PE1, the operator initiates an LSP Ping request with the target FEC stack TLV containing EVPN IP Prefix sub-TLV in the echo request packet. The echo request packet is sent with the {Transport label(s) to reach PE1 + EVPN IP Prefix Label 20001 } MPLS label stack.
When PE1 receives the packet it will process the packet and perform checks for the EVPN IP Prefix sub-TLV present in the Target FEC Stack TLV as described in Section 4.4 in [RFC8029] and respond according to [RFC8029] processing rules.
The proposal introduced in this document does not introduce any new security considerations beyond that already apply to [RFC7432], [RFC7623] and [RFC6425].
This document defines 4 new sub-TLV type to be included in Target FEC Stack TLV (TLV Type 1) [RFC8029] in LSP Ping.
IANA is requested to assign a sub-TLV type value to the following sub-TLV from the "Multiprotocol Label Switching (MPLS) Label Switched Paths (LSPs) Parameters - TLVs" registry, "TLVs and sub- TLVs" sub-registry:
[RFC8029] defines values for the Return Code field of Echo Reply. This document proposes two new Return Codes, which SHOULD be included in the Echo Reply message by a PE in response to LSP Ping Echo Request message:
1. The FEC exists on the PE and the behavior is to drop the packet because of not DF.
2. The FEC exists on the PE and the behavior is to drop the packet because of Split Horizon Filtering.
The authors would like to thank Patrice Brissette and Weiguo Hao for their comments.
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC4875] | Aggarwal, R., Papadimitriou, D. and S. Yasukawa, "Extensions to Resource Reservation Protocol - Traffic Engineering (RSVP-TE) for Point-to-Multipoint TE Label Switched Paths (LSPs)", RFC 4875, DOI 10.17487/RFC4875, May 2007. |
| [RFC5085] | Nadeau, T. and C. Pignataro, "Pseudowire Virtual Circuit Connectivity Verification (VCCV): A Control Channel for Pseudowires", RFC 5085, DOI 10.17487/RFC5085, December 2007. |
| [RFC6338] | Giralt, V. and R. McDuff, "Definition of a Uniform Resource Name (URN) Namespace for the Schema for Academia (SCHAC)", RFC 6338, DOI 10.17487/RFC6338, August 2011. |