BGP Community String for nLayer Communications AS4436

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Attention

This BGP Community string information might be outdated. Please contact nLayer Communications AS4436 to get more recent one. This BGP communites is ONLY for the customer who has BGP with nLayer Communications AS4436. www.ipbalance.com is not maintaining this BGP Community string.

Peer BGP Policies

This section describes the policies for routing announcements received from and announced to external eBGP peers and transits.

Multi Exit Discriminator (MED) Policy

MEDs received from peers will be ignored by default, unless prior arrangements have been made to confirm the quality of the values.

MEDs are announced by default, using good aggregates and meaningful values based on IGP costs. Peers may decide to honor these MEDs at their discretion.

Damping Policy

Routing flaps from eBGP peers may be progressively dampened, based on prefix lengths as describe in the table below. This is done to protect our network from the instabilities of other announcements on the Internet.

Prefix Length Filtering

Announcements received from peers are filtered against a list of bogon blocks, as well as by prefix length. The shortest prefix length which will be accepted from any network is a /5, the longest prefix length which will be accepted is a /24.

Outbound announcements from nLayer will never exceed /24 in length. All routes announced will be registered in the Internet Routing Registry (IRR) databases under the as-set AS-NLAYER.

 

Damping Policy
Prefix Length	Half-life	Reuse Limit	Suppress Limit	Max Suppress
/24 or longer	10	7000	10000	15
/20 – /23	5	7000	10000	10
/17 – /19	3	7000	10000	5
/16 or shorter	1	10000	15000	2

 

 

 

Customer BGP Policies

This section describes the policies for routing announcements received from and announced to customers speaking BGP, including information on how customers may use BGP community tags to influence nLayer routing policy for their announcements.

Receivable BGP Communities

 

 

Customers may influence nLayer routing policies by a number of BGP community tags which may be set on routes which they announce. These tags can control the propagation of routes, adjust the localpref assigned to them, and even null route traffic.

 

Announced BGP Communities

 

All routes announced to customers are tagged with the following information:

 

4436:TCRI

 

T: The type of relationship that the route was learned through.
C: The continent where the route was learned.
R: The region where the route was learned, if in the US.
I: Internal usage only.

 

IRR Filtering

 

All customers announcements are filtered against Internet Routing Registry (IRR) databases. BGP speaking customers will be expected to maintain current and correct IRR entries.

 

All nLayer announcements will be recorded under the as-set AS-NLAYER.

 

 

 

 

Receivable BGP Communities

Receivable BGP Communities
BGP Community String	Action
4436:1	Prepend 4436 to route
4436:2	Prepend 4436 4436 to route
4436:3	Prepend 4436 4436 4436 to route
4436:50	Set local preference to 50
4436:100	Set local preference to 100
4436:150	Set local preference to 150
4436:200	Set local preference to 200
4436:250	Set local preference to 250
4436:300	Set local preference to 300
4436:555	Null route (discard) traffic
4436:666	Do not export to anyone
4436:777	Do not export to transits
4436:888	Do not export to peers
4436:999	Do not export to customers

 

Special BGP Communities
BGP Community String	Action
ASN:1	Prepend 4436 to ASN
ASN:2	Prepend 4436 4436 to ASN
ASN:3	Prepend 4436 4436 4436 to ASN
ASN:666	Do not announce to ASN

 

Announced BGP Communities
Value	Type	Continent	US Region
1	Public Peer	North America	NYC
2	Private Peer	Europe	IAD
3	Transit	Asia	ATL
4	Customer	Australia	ORD
5	Internal	South America	KCY
6		Middle East	DFW
7			SEA
8			SJC
9			LAX

 

Local Preferences
Localpref	Description
50	Depreferenced transit route
100	Default transit route
150	Depreferenced peering route
200	Default peering route
250	Depreferenced customer route
300	Default customer route
400	Default internal route

 

 

 

Applying BGP Community string with sample configuration

2. Pick the best BGP community string for your traffic shaping plan (mainly incoming traffic). Most of ISPs are providing BGP community string with local preference and AS prepending option. Cannot tell which one is better than the other. It will depend on your global traffic shaping plan.

3. Follow the below commands ( Cisco only )

The below Sample configuration will tag the 10.0.0.0/24 route with [ISP AS]:120 or [ISP AS]:3 and will not tag any other routes.

router#config t
router(config)#ip bgp-community new-format
router(config)#access-list 10 permit 10.0.0.0 0.0.0.255
router(config)#access-list 10 deny any

router(config)#route-map [to-ISP] permit 10
router(config-route-map)#match ip address 10
router(config-route-map)#set community [ISP AS]:120 <—- using Local Preference

or

router(config-route-map)#set community [ISP AS]:3 <——- using AS prepending
router(config-route-map)#route-map [to-ISP] permit 20
router(config-route-map)#exit

router(config)#router bgp [xxxx] <——————————- xxxx = customer’s ASN
router(config-router)#neighbor x.x.x.x send-community
router(config-router)#neighbor x.x.x.x route-map [to-ISP] out
router(config-router)#exit
router(config)#exit
router#copy running-config startup-config

4. And then, go to www.RouteServer.org and pick one of route server on the map to see your announcement. If you are using AS prepending option, you will see your AS prepends on route servers. Sometime you might not see your route with particular ISP path.
In most of case it might not be any routing problem, just the route path was dropped at somewhere by BGP best path selection scheme. Try Oregon route server, if you can see your route. The Oregon route server is providing many possible and available paths between BGP speakers and neighbors.
If you don’t see your route on there? check other route servers and also check your
BGP configuration. You might need to contact your upstream provider to check what they are learning BGP route from you.