Home BGP Tools BGP Community List nLayer Communications AS4436

nLayer Communications AS4436


This BGP Community string information might be outdated. Please contact nLayer Communications to get more recent one. This BGP communites is ONLY for the customer who has BGP with nLayer Communications AS4436. Showipbgp.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:


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
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
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

**Information source below to see recent update


Applying BGP Community string with sample configuration

1. Get the latest BGP community string from your ISP/upstream provider or check new.CiscoNET.com web site.

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 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
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


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

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#copy running-config startup-config

4. And then, go to www.CiscoNET.com 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.


* We do NOT support or maintain any BGP community string
** Contact ISP to get more detail information

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