As carriers improve IP networks, the BFD technology is being widely used. A Huawei device unavoidably sets up BFD sessions with other non-Huawei devices. When a Huawei device is connected to an R device from E supplier, the R device continuously generates the following alarms.
Feb 21 15:06:53.231: : %RSVP-7-PING: [rsvp_lsp_ping_handler] received a mpls ping for endpoint 10.0.1.15, tunnel_id 108 extended tunnel_id 10.0.1.4, sender 10.0.11.26 lsp_id 1
Feb 21 15:06:53.231: : %RSVP-7-PING: [rsvp_lsp_ping_handler] in interface 10.0.12.17 in nbr 10.0.1.15
Feb 21 15:06:53.232: : %RSVP-7-PING: [rsvp_lsp_ping_handler] RSVP returns code 3 in interface 10.0.12.17 in nbr 10.0.1.15 out interface 0.0.0.0 out nbr 0.0.0.0 out_mtu 0
Feb 21 15:06:53.232: %LM-3-ERR: Unsupported Echo request tlv 15 - reply with error code
1. The on-site Huawei technical support personnel consults E supplier's technical support personnel on the key information in the alarm "Unsupported Echo request tlv 15 - reply with error code". E supplier's technical support personnel explain that R devices support TLVs defined in RFC 4379. RFC 4379 defines TLVs with the Type field ranging from 1 to 10 only. When the R device receives LSP ping messages carrying a BFD discriminator TLV with the type field 15 from the Huawei device, the R device fails to identify the TLV in the LSP ping messages and generates an alarm as a result.
RFC 4379 defines TLVs as follows:
TLVs and sub-TLVs defined in this document are the following:
Type Sub-Type Value Field
---- -------- -----------
1 Target FEC Stack
1 LDP IPv4 prefix
2 LDP IPv6 prefix
3 RSVP IPv4 LSP
4 RSVP IPv6 LSP
5 Not Assigned
6 VPN IPv4 prefix
7 VPN IPv6 prefix
8 L2 VPN endpoint
9 "FEC 128" Pseudowire (Deprecated)
10 "FEC 128" Pseudowire
11 "FEC 129" Pseudowire
12 BGP labeled IPv4 prefix
13 BGP labeled IPv6 prefix
14 Generic IPv4 prefix
15 Generic IPv6 prefix
16 Nil FEC
2 Downstream Mapping
4 Not Assigned
5 Vendor Enterprise Number
6 Not Assigned
7 Interface and Label Stack
8 Not Assigned
9 Errored TLVs
Any value The TLV not understood
10 Reply TOS Byte
Then the on-site Huawei technical support personnel collect information about the Huawei device from a Huawei BFD professional. The Huawei device supports RFC 5884 in which the IANA defines that the Type field value in a BFD discriminator TLV carried in LSP ping messages is 15. The alarm is generated because the R device from E supplier does not support RFC 5884.
RFC 5884 defines BFD discriminator TLV in LSP ping messages as follows.
6.1. BFD Discriminator TLV in LSP Ping
LSP Ping Echo request and Echo reply messages carry a BFD
discriminator TLV for the purpose of session establishment as
described above. IANA has assigned a type value of 15 to this TLV.
This TLV has a length of 4. The value contains the 4-byte local
discriminator that the LSR, sending the LSP Ping message, associates
with the BFD session.
If the BFD session is not in UP state, the periodic LSP Ping Echo
request messages MUST include the BFD Discriminator TLV.
The cause for the problem lies in that the R device from E supplier does not support RFC 5884 that is the latest release. To resolve the problem, the software version running on the R device must be upgraded.
upgrade the E device.