BGP Community String for Savvis Communications AS3561

Tweet

Attention

This BGP Community string information might be outdated. Please contact Savvis Communications AS3561 to get more recent one. This BGP communites is ONLY for the customer who has BGP with Savvis Communications AS3561. www.ipbalance.com is not maintaining this BGP Community string.

 

1. SAVVIS Received BGP Community Attribute Values (BGP community String)

SAVVIS Prepend/Suppression BGP Community Attribute Values (3561:30PPN)

SAVVIS allows customers to control certain traffic flows off-net with the implementation of BGP community attribute values that prepend route/prefix paths with additional AS hops. These BGP community attribute values, which the customer applies, affects the way SAVVIS peers choose the degree of preference of a given prefix/route, because the number of AS hops within the route-path has been lengthened.

The format for the second component of customer route BGP community number (after 3561:) is set at five digits. This fixed length allows regular expressions to be used in applying a defined number of prepends to a given route/prefix path. This format is 3561:30PPN, where the fields are coded in the following way. (Note: The first 2 digits of the second component are always "30" then followed by variables of the "PP" and "N" variables which are defined in the following tables.)

The "PP" variable cross references peers of SAVVIS, defined in the following table. (Note, this will always be a two digit value.)

 

PP Code	Peer Name	Peer AS Number
00	All Peers	–
01	SBC	AS7132
02	Sprint	AS1239
03	Tiscali	AS3257
04	Qwest	AS209
06	Verio/NTT	AS2914
07	Level3	AS3356
08	GlobalCrossing	AS3549
09	FranceTelecom	AS5511
10	WilliamsCommunicationsGroup	AS7911
11	DeutscheTelekomAG	AS3320
12	XOCommunications	AS2828
13	AboveNet/MFN	AS6461
14	UUNet	AS701
15	AT&T	AS7018
18	Cogent	AS174
21	ATDN	AS1668
41	Colt	AS8220
43	Infonet	AS3300
44	UUNet-EU	AS702
46	Telia	AS1299

 

 

 

N Values

"N" Value Meaning

0 Do not export
1 Prepend once
2 Prepend twice
3 Prepend three times
9 Announce-only

Examples:

3561:30030 Do not export this route to PSINet (AS174)
3561:30142 Prepend this route twice, to UUNet (AS701)
3561:30159 Announce this route only to AT&T (AS7018)
SAVVIS Blackhole BGP Community Attribute Values (3561:666)

For customers that have a host or block under a DDoS, the affected host/block can be advertised to AS3561 with BGP community string 3561:666. This will cause all traffic to that host to be black-holed at the core of the AS3561 network. This action will trigger emails sent to the appropriate security and operations groups for notification purposes.

After advertising the prefix with 3561:666, the customer should open a priority one incident report with Client Services:

SAVVIS Support Center (SSC)

Phone: 888-638-6771

email: [email protected]

Once the attack has been mitigated, the customer will be responsible for removing the prefix from being advertised.

SAVVIS will not be held responsible for customers who errantly advertise prefixes with the blackhole BGP community string.

SAVVIS Received BGP Community Attribute Values

 

Value: 3561:70
Definition:Sets local preference value within AS3561 to "70".

Value: 3561:80
Definition:Sets local preference value within AS3561 to "80".

Value: 3561:90
Definition:Sets local preference value within AS3561 to "90".

Value: 3561:no-export or 3561:no-advertise
Definition: Will prevent the network/prefix tagged with this (either) BGP community attribute from being announced outside AS3561. Note, this will prevent the route from being propagated to SAVVIS eBGP customers receiving a routing table.

2. SAVVIS Announced BGP Community Attribute Values

Formerly, only two SAVVIS BGP community attribute values were announced to users upon request: 3561:900 (customer routes) and 3561:999 (peer routes). These have been replaced by a new BGP community string implementation.

The new implementation allows for a 5 digit string, following the "3561:" notation. Each bit/digit has a pertinent value and meaning represented in the following tables (3561:xxxxx)

This was facilitated to provide the following routing information to customers receiving a routing table from SAVVIS via eBGP routing.

Identification of route source by a. Customer or peer b. Region – Predefined by SAVVIS – Based upon physical connection point c. Country – Predefined by SAVVIS – Based upon physical connection point

The format for the second component of customer route BGP community number (after 3561:) is set at five digits. This fixed length allows regular expressions to be used in routing policy statements to select subsets of customer routes. This format is 3561:SRCCC where the fields are coded in the following way.

"S" refers to ‘source’ of the route: Source Codes Code Source 1 Customer 2 Peer Example: 3561:1xxxx customer route 3561:2xxxx peer route

"R" defines the region, as specified in Table 3-1. Codes 7 through 0 that are not defined yet and thus available for future region definitions. Since there are only four available region codes left, the definition of each code shall await a need for the function it would provide.

Regional Codes Code Region 1 North America (U.S.A and Canada) 2 Europe 3 Asia (including Japan) 4 Australia 5 South America 6 Middle East 7 Available for future region definitions 8 Available for future region definitions 9 Available for future region definitions 0 Available for future region definitions Example: 3561:11xxx customer, North America 3561:24xxx peer, Australia

"CCC" signifies country code defined by ISO 3166 codes for countries. Note: Peers use a country code of "000".

 

 

 

 

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.