| Global Routing Operations | T. Evens |
| Internet-Draft | S. Bayraktar |
| Updates: 7854 (if approved) | Cisco Systems |
| Intended status: Standards Track | P. Lucente |
| Expires: September 3, 2018 | NTT Communications |
| P. Mi | |
| Tencent | |
| S. Zhuang | |
| Huawei | |
| March 2, 2018 |
Support for Adj-RIB-Out in BGP Monitoring Protocol (BMP)
draft-ietf-grow-bmp-adj-rib-out-01
The BGP Monitoring Protocol (BMP) defines access to only the Adj-RIB- In Routing Information Bases (RIBs). This document updates the BGP Monitoring Protocol (BMP) RFC 7854 by adding access to the Adj-RIB- Out RIBs. It adds a new flag to the peer header to distinguish Adj- RIB-In and Adj-RIB-Out.
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on September 3, 2018.
Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved.
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BGP Monitoring Protocol (BMP) defines monitoring of the received (e.g. Adj-RIB-In) Routing Information Bases (RIBs) per peer. The Adj-RIB-In pre-policy conveys to a BMP receiver all RIB data before any policy has been applied. The Adj-RIB-In post-policy conveys to a BMP receiver all RIB data after policy filters and/or modifications have been applied. An example of pre-policy verses post-policy is when an inbound policy applies attribute modification or filters. Pre-policy would contain information prior to the inbound policy changes or filters of data. Post policy would convey the changed data or would not contain the filtered data.
Monitoring the received updates that the router received before any policy has been applied is the primary level of monitoring for most use-cases. Inbound policy validation and auditing is the primary use-case for enabling post-policy monitoring.
In order for a BMP receiver to receive any BGP data, the BMP sender (e.g. router) needs to have an established BGP peering session and actively be receiving updates for an Adj-RIB-In.
Being able to only monitor the Adj-RIB-In puts a restriction on what data is available to BMP receivers via BMP senders (e.g. routers). This is an issue when the receiving end of the BGP peer is not enabled for BMP or when it is not accessible for administrative reasons. For example, a service provider advertises prefixes to a customer, but the service provider cannot see what it advertises via BMP. Asking the customer to enable BMP and monitoring of the Adj-RIB- In is not feasible.
This document updates BGP Monitoring Protocol (BMP) RFC 7854 peer header by adding a new flag to distinguish Adj-RIB-In verses Adj-RIB-Out.
Adding Adj-RIB-Out enables the ability for a BMP sender to send to a BMP receiver what it advertises to BGP peers, which can be used for outbound policy validation and to monitor RIBs that were advertised.
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 RFC 2119.
The per-peer header has the same structure and flags as defined in section 4.2 with the following O flag addition:
0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |V|L|A|O| Resv | +-+-+-+-+-+-+-+-+
The existing flags are defined in section 4.2 and the remaining bits are reserved for future use. They SHOULD be transmitted as 0 and their values MUST be ignored on receipt.
The primary use-case in monitoring Adj-RIB-Out is to monitor the updates transmitted to the BGP peer after outbound policy has been applied. These updates reflect the result after modifications and filters have been applied (e.g. Adj-RIB-Out Post-Policy). Some attributes are set when the BGP message is transmitted, such as next-hop. Adj-RIB-Out Post-Policy MUST convey what is actually transmitted to the peer, next-hop and any attribute set during transmission should also be set and transmitted to the BMP receiver.
The L flag MUST be set to 1 to indicate post-policy.
As with Adj-RIB-In policy validation, there are use-cases that pre- policy Adj-RIB-Out is used to validate and audit outbound policies. For example, a comparison between pre-policy and post-policy can be used to validate the outbound policy.
Depending on BGP peering session type (IBGP, IBGP route reflector client, EBGP) the candidate routes that make up the Pre-Policy Adj-RIB-Out do not contain all local-rib routes. Pre-Policy Adj-RIB-Out conveys only routes that are available based on the peering type. Post-Policy represents the filtered/changed routes from the available routes.
Some attributes are set only during transmission of the BGP message, e.g. Post-Policy. It is common that next-hop may be null, loopback, or similar during this phase. All mandatory attributes, such as next-hop, MUST be either ZERO or have an empty length if they are unknown at the Pre-Policy phase. The BMP receiver will treat zero or empty mandatory attributes as self originated.
The L flag MUST be set to 0 to indicate pre-policy.
Many BMP messages have a per-peer header but some are not applicable to Adj-RIB-In or Adj-RIB-Out monitoring. Unless otherwise defined, the O flag should be set to 0 in the per-peer header in BMP messages.
The O flag MUST be set accordingly to indicate if the route monitor or route mirroring message conveys Adj-RIB-In or Adj-RIB-Out.
Statistics report message has Stat Type field to indicate the statistic carried in the Stat Data field. Statistics report messages are not specific to Adj-RIB-In or Adj-RIB-Out and MUST have the O flag set to zero. The O flag SHOULD be ignored by the BMP receiver.
The following new statistic types are added:
PEER UP and DOWN notifications convey BGP peering session state to BMP receivers. The state is independent of whether or not route monitoring or route mirroring messages will be sent for Adj-RIB-In, Adj-RIB-Out, or both. BMP receiver implementations SHOULD ignore the O flag in PEER UP and DOWN notifications. BMP receiver implementations MUST use the per-peer header O flag in route monitoring and mirroring messages in order to identify if the message is for Adj-RIB-In or Adj-RIB-Out.
The following peer UP information TLV types are added:
Peer and update groups are used to group updates shared by many peers. This is a level of efficiency in the implementation, not a true representation of what is conveyed to a peer in either Pre-Policy or Post-Policy.
One of the use-cases to monitor Adj-RIB-Out Post-Policy is to validate and continually ensure the egress updates match what is expected. For example, wholesale peers should never have routes with community X:Y sent to them. In this use-case, there maybe hundreds of wholesale peers but a single peer could have represented the group.
A single peer could be used to represent a group. From a BMP perspective, this should be simple to include a group name in the PEER UP, but it is more complex than that. BGP implementations have evolved to provide comprehensive and structured policy grouping, such as session, afi/safi, and template based group policy inheritances.
This level of structure and inheritance of polices does not provide a simple peer group name or ID, such as wholesale peer.
Instead of requiring a group name to be used, a new administrative label informational TLV (Section 6.3.1) is added to the Peer UP message. These labels have administrative scope relevance. For example, labels "type=wholesale" and "region=west" could be used to monitor expected policies.
Configuration and assignment of labels to peers is BGP implementation specific.
It is not believed that this document adds any additional security considerations.
This document requests that IANA assign the following new parameters to the BMP parameters name space.
This document defines the following new per-peer header flags (Section 4):
This document defines four new statistic types for statistics reporting (Section 6.2):
This document defines the following new BMP PEER UP informational message TLV types (Section 6.3.1):
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC4271] | Rekhter, Y., Li, T. and S. Hares, "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI 10.17487/RFC4271, January 2006. |
| [RFC7854] | Scudder, J., Fernando, R. and S. Stuart, "BGP Monitoring Protocol (BMP)", RFC 7854, DOI 10.17487/RFC7854, June 2016. |
The authors would like to thank John Scudder for his valuable input.
Manish Bhardwaj
Cisco Systems
3700 Cisco Way
San Jose, CA 95134
USA
Email: manbhard@cisco.com
Xianyuzheng
Tencent
Tencent Building, Kejizhongyi Avenue,
Hi-techPark, Nanshan District,Shenzhen 518057, P.R.China
Weiguo
Tencent
Tencent Building, Kejizhongyi Avenue,
Hi-techPark, Nanshan District,Shenzhen 518057, P.R.China
Shugang cheng
H3C