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BGP LS support
BGP Link State, as defined in RFC 7752, defines a way in which an IGP node can export and transport its link state database using BGP. In the context of MPLS TE this database contains not only topology information but also the extensions required to perform traffic engineering. Making these bits available to a northbound entity (hence the "North-Bound Distribution" in the RFC title) can be useful in areas like LSP optimization, custom path computation, monitoring, etc.
ExaBGP can be used as such northbound entity, receiving and decoding BGP-LS information from a device and then probably feeding this data to a separate process. With the information received you could then perform offline CSPF computations, link monitoring and many more.
If your device supports segment routing, ExaBGP is also able to parse IS-IS segment routing extensions through BGP-LS. This means that you can effectively receive segment identifiers, both node and adjacency ids, through the same BGP-LS session. With label information available your ExaBGP instance is ready to program those infrastructure LSPs for you via BGP-LU session with the PEs!
The exact name of the family and JSON fields may change slightly before the next release during the 4.0 development process.
A working ExaBGP configuration could look like the following:
process parsed-route-backend {
run /home/ruissalo/exabgp/etc/exabgp/processes/file.py;
encoder json;
}
neighbor 10.30.4.3 {
local-address 10.30.4.2;
local-as 65050;
peer-as 65000;
family bgpls {
bgp-ls;
}
api {
processes [ parsed-route-backend ];
receive {
parsed;
update;
}
}
}
There are basically three types of JSON structures in the current implementation, one for each NRLI type: NODE, LINK and PREFIX. They are uniquely identified by the value in "ls-nlri-type" according to the following table:
__________________
| ID | NLRI Type |
| ---|-------------|
| 1 | Node NLRI |
| 2 | Link NLRI |
| 3 | Prefix NLRI |
--------------------
Examples of each of these data types follow below, please note that they do not represent the full set of possible TLVs.
Node JSON:
{
"exabgp":"4.0.1",
"time":1498264977.29,
"host":"ruissalo",
"pid":83836,
"ppid":60690,
"counter":1,
"type":"update",
"neighbor":{
"address":{
"local":"192.0.2.5",
"peer":"192.0.2.79"
},
"asn":{
"local":"65000",
"peer":"65000"
},
"direction":"in",
"message":{
"update":{
"attribute":{
"origin":"igp",
"as-path":[
65000
],
"confederation-path":[
],
"bgp-ls":{
"node-flags":{
"B":0,
"E":0,
"T":0,
"O":0
},
"area-id":"490002",
"local-te-router-id":"192.0.2.88",
"sr-capability-flags":{
"I":1,
"RSV":0,
"V":0
},
"sids":[
[
501,
1000000
]
]
}
},
"announce":{
"bgpls bgp-ls":{
"192.0.2.52":[
{
"ls-nlri-type":1,
"l3-routing-topology":0,
"protocol-id":2,
"node-descriptors":{
"autonomous-system":65000,
"router-id":"172000160088"
},
"nexthop":"192.0.2.52"
}
]
}
}
}
}
}
}
Link JSON
{
"exabgp":"4.0.1",
"time":1498265291.09,
"host":"ruissalo",
"pid":84580,
"ppid":60690,
"counter":1,
"type":"update",
"neighbor":{
"address":{
"local":"192.0.2.5",
"peer":"192.0.2.79"
},
"asn":{
"local":"65000",
"peer":"65000"
},
"direction":"in",
"message":{
"update":{
"attribute":{
"origin":"igp",
"as-path":[
65000
],
"confederation-path":[
],
"bgp-ls":{
"admin-group-mask":[
0
],
"maximum-link-bandwidth":125000000.0,
"maximum-reservable-link-bandwidth":125000000.0,
"unreserved-bandwidth":[
125000000.0,
125000000.0,
125000000.0,
125000000.0,
125000000.0,
125000000.0,
125000000.0,
125000000.0
],
"te-metric":10,
"igp-metric":10,
"sr-adj-flags":{
"B":0,
"F":0,
"L":1,
"P":0,
"S":0,
"V":1,
"RSV":0
},
"sids":[
299808
],
"sr-adj-weight":0
}
},
"announce":{
"bgpls bgp-ls":{
"192.0.2.52":[
{
"ls-nlri-type":2,
"l3-routing-topology":0,
"protocol-id":2,
"local-node-descriptors":{
"autonomous-system":65000,
"router-id":"172000160002"
},
"remote-node-descriptors":{
"autonomous-system":65000,
"router-id":"172000160001"
},
"interface-address":{
"interface-address":"192.0.2.25"
},
"neighbor-address":{
"neighbor-address":"192.0.2.24"
}
},
{
"ls-nlri-type":2,
"l3-routing-topology":0,
"protocol-id":2,
"local-node-descriptors":{
"autonomous-system":65000,
"router-id":"172000160001"
},
"remote-node-descriptors":{
"autonomous-system":65000,
"router-id":"172000160002"
},
"interface-address":{
"interface-address":"192.0.2.24"
},
"neighbor-address":{
"neighbor-address":"192.0.2.25"
}
},
{
"ls-nlri-type":2,
"l3-routing-topology":0,
"protocol-id":2,
"local-node-descriptors":{
"autonomous-system":65000,
"router-id":"172000160033"
},
"remote-node-descriptors":{
"autonomous-system":65000,
"router-id":"172000160001"
},
"interface-address":{
"interface-address":"192.0.2.9"
},
"neighbor-address":{
"neighbor-address":"192.0.2.8"
}
}
]
}
}
}
}
}
}
Prefix JSON
{
"exabgp":"4.0.1",
"time":1498265704.66,
"host":"ruissalo",
"pid":84678,
"ppid":60690,
"counter":1,
"type":"update",
"neighbor":{
"address":{
"local":"192.0.2.5",
"peer":"192.0.2.5"
},
"asn":{
"local":"65000",
"peer":"65000"
},
"direction":"in",
"message":{
"update":{
"attribute":{
"origin":"igp",
"local-preference":100,
"bgp-ls":{
"sr-prefix-flags":{
"E":0,
"L":0,
"N":1,
"P":0,
"R":0,
"V":0,
"RSV":0
},
"sids":[
200
],
"sr-algorithm":0
}
},
"announce":{
"bgpls bgp-ls":{
"192.0.2.1":[
{
"ls-nlri-type":3,
"l3-routing-topology":0,
"protocol-id":2,
"node-descriptors":{
"autonomous-system":65000,
"router-id":"100000000004"
},
"ip-reachability-tlv":"192.0.2.100",
"nexthop":"192.0.2.1"
}
]
}
}
}
}
}
}
(Data above doesn't represent any real topology, it was taken from real routers but was anonymized)
- Juniper
You can check here for details on how to set up a Juniper device to enable the distribution of link state information.
- Cisco
Config guide for PCEP and BGP-LS can be found here
Before submitting any bug report make sure link state data is actually being exported from the TED (Junos) or IS-IS database (Cisco):
- Junos:
show route table lsdist.0
lsdist.0: 37 destinations, 37 routes (37 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
NODE { AS:65000 ISO:1720.0000.0202.00 ISIS-L2:0 }/1152
*[IS-IS/18] 00:27:31
Fictitious
LINK { Local { AS:65000 ISO:1720.0016.0088.00 }.{ IPv4:172.24.248.79 } Remote { AS:65000 ISO:1720.0016.0011.00 }.{ IPv4:172.24.248.52 } ISIS-L2:0 }/1152
*[IS-IS/18] 00:28:29
Fictitious
PREFIX { Node { AS:65000 ISO:1720.0016.0001.00 } { IPv4:172.16.0.1/32 } ISIS-L2:0 }/1152
*[IS-IS/18] 00:27:26
Fictitious
PREFIX { Node { AS:65000 ISO:1720.0016.0002.00 } { IPv4:172.16.0.2/32 } ISIS-L2:0 }/1152
And that it is also being advertised to the ExaBGP neighbor:
show route advertising-protocol bgp 10.30.4.3 | match "NODE|LINK|PREFIX"
- Cisco
RP/0/RP0/CPU0:ios#show bgp link-state link-state
Status codes: s suppressed, d damped, h history, * valid, > best
i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
Prefix codes: E link, V node, T IP reacheable route, u/U unknown
I Identifier, N local node, R remote node, L link, P prefix
L1/L2 ISIS level-1/level-2, O OSPF, D direct, S static/peer-node
a area-ID, l link-ID, t topology-ID, s ISO-ID,
c confed-ID/ASN, b bgp-identifier, r router-ID,
i if-address, n nbr-address, o OSPF Route-type, p IP-prefix
d designated router address
Network Next Hop Metric LocPrf Weight Path
*> [V][L2][I0x0][N[c1.119][b172.24.248.230][s1720.0000.0202.00]]/328
0.0.0.0 0 i
*> [V][L2][I0x0][N[c1.119][b172.24.248.230][s1720.0016.0001.00]]/328
0.0.0.0 0 i
*> [V][L2][I0x0][N[c1.119][b172.24.248.230][s1720.0016.0002.00]]/328
0.0.0.0 0 i
*> [V][L2][I0x0][N[c1.119][b172.24.248.230][s1720.0016.0011.00]]/328
0.0.0.0 0 i
*> [V][L2][I0x0][N[c1.119][b172.24.248.230][s1720.0016.0013.00]]/328
0.0.0.0 0 i
(...)
If you still think the problem is a bug, please open an issue and include the console output using the -d flag:
exabgp -d config.ini
+--------+---------+--------+
| | IOS-XR* | JUNOS* |
+--------+---------+--------+
| Rcv.N1 | YES | YES |
| Org.N1 | NO | NO |
| Rcv.N2 | YES | YES |
| Org.N2 | NO | NO |
| Rcv.N3 | YES | YES |
| Org.N3 | NO | NO |
| Rcv.N4 | NO | NO |
| Org.N4 | NO | NO |
+--------+---------+--------+
- N1: Node NLRI
- N2: Link NLRI
- N3: IPv4 Topology Prefix NLRI
- N4: IPv6 Topology Prefix NLRI
- Rcv: Receive and decode capability
- Org: Encode and Originate Capability
ExaBGP should work with any other BGP-LS implementation, in particular the following systems:
- IOS-XR 6.1.1 (There is a bug in the TLV 1158 implementation on this version where V and L are not set correctly)
- Junos 15.1F6.9 (This version doesn't originate N3/N4 NLRIs)
- Junos 17.2R1.13 (First version that supports Prefix NLRI)
ExaBGP is able to receive and decode the following TLV types:
- LINK NLRI
TLV 256: Local Node Descriptor
TLV 257: Remote Node Descriptor
TLV 258: Link Local/Remote Identifier
TLV 259: IPv4 Interface address
TLV 260: IPv4 Neighbor address
TLV 263: Multi-Topology IDs
TLV 512: Autonomous System
TLV 513: BGP-LS Identifier
TLV 514: Area ID
TLV 515: IGP Router ID
TLV 1028: IPv4 router-ID of Local Node
TLV 1030: IPv4 router-ID of Remote Node
TLV 1088: Administrative group (color)
TLV 1089: Maximum link bandwidth
TLV 1090: Maximum reservable link bandwidth
TLV 1091: Unreserved link bandwidth
TLV 1092: TE default Metric
TLV 1093: Link Protection Type
TLV 1094: MPLS Protocol Mask
TLV 1095: IGP Metric
TLV 1096: Shared Risk Link Group
TLV 1098: Link name attribute
- NODE NLRI
TLV 256: Local Node Descriptor
TLV 263: Multi-Topology IDs
TLV 512: Autonomous System
TLV 513: BGP-LS Identifier
TLV 514: Area ID
TLV 515: IGP Router ID
TLV 1024: Node flag bits
TLV 1026: Node name
TLV 1027: IS-IS Area Identifier
TLV 1028: IPv4 router-ID of Local Node
- PREFIX NLRI:
TLV 263: Multi-Topology IDs
TLV 264: OSPF route type
TLV 265: IP Reachability information
TLV 1152: IGP Flags
TLV 1153: Route Tag
TLV 1154: Extended Tag
TLV 1155: Prefix Metric
TLV 1156: OSPF Forwarding Address
Segment routing IS-IS extensions https://datatracker.ietf.org/doc/draft-gredler-idr-bgp-ls-segment-routing-ext/03/
- NODE NLRI:
TLV 1034: SR Capabilities
TLV 1035: SR Algorithm
- LINK NLRI:
TLV 1099: Adjacency Segment Identifier (Adj-SID) TLV
TLV 1100: LAN Adjacency Segment Identifier (Adj-SID) TLV
- PREFIX NLRI:
TLV 1158: Prefix SID
TLV 1170: IGP Prefix Attributes
TLV 1171: Source Router-ID
TLV 1161: SID/Label TLV
-
Encoding and sending capabilities for all NLRIs.
-
Decoding for the following TLVs:
NODE NLRI:
TLV 1029: IPv6 router-ID of Local Node
TLV 1025: Opaque Node properties
LINK NLRI:
TLV 1029: IPv6 router-ID of Local Node
TLV 1031: IPv6 router-ID of Remote Node
TLV 261: IPv6 Interface address
TLV 262: IPv6 Neighbor address
PREFIX NLRI:
TLV 1157: Opaque Prefix Attribute
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