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BGP is Border Gateway Protocol, used on the internet both inside of and in between networks.

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design - Cisco ACI and Nexus 7ks - best choice OSPF or EBGP

We have two data centers as shown in the picture. Data center 1 and data center 2. At each data center 1) Nexus 7ks have 3 VDC's configured . WAN_VDC is connected to Cisco ACI using L3 Port ...
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40 views

GNS3 - BGP and OSPF redistribution

Hello Guys, referring to the picture, I have configured ebgp between R1 and ISP 1, and R2 and ISP2. iBGP has been configured in a full mesh internally on top of OSPF. All neighbors are up and peered ...
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1answer
56 views

Why use iBGP over eBGP?

Why would you use iBGP over eBGP. i.e why use a single AS with an RR over multiple AS's using eBGP. Is it simply for peering design simplification i.e large amount of devices all peering to a set of ...
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1answer
126 views

Config BGP policy for limit ISP path in Juniper MX 480 Router

Now we have a source IP14.135.4.0/24, we are involved in 5 different ISP, such as A, B, C, D, E. Now we want to access 14.135.4.0/24 not through the path of ISP B and ISP D, but through the other ...
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1answer
23 views

Routing an owned /24 IPv4 block to a single server

How would one go about routing a recently-purchased /24 block of IPv4's to a single server? The server is colocated in Zare.com, and the BGP session is already set up and announced.
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1answer
62 views

How to find a AS-SET of an asn?

How can we find the as-set of asn? For Example I have the asn:32934. I want the as-set?
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2answers
52 views

BGP with x2 sessions and x2 L3 VLANs - Please Explain

I am learning about Cisco BGP networking now and came across an interesting situation. In my examples, there was one which suggested that two VLANs were configured on Layer 3 in order to run two BGP ...
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1answer
60 views

Unable to route Public IPs over private network

I have the following setup; Router A Interface 1: 23.128.1.1/24 Route added on Router A to access 10.10.0.1/24 via 23.128.1.2 Router B Interface 1: 23.128.1.2/24 VPN Interface: 10.10.0.1/24 VPN ...
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1answer
42 views

How can I reduce latency to Australia from another country? [closed]

I often do a lot of work from the UK to destination networks in Australia be it voice calls or something more benign like gaming. Both of which work best with the lowest RTT possible. On average the ...
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1answer
35 views

Can i implement BGP flowspec

This question is for general information about BGP flowspec, Can i implement BGP flowspec to stop DDoS? RTBH isn't what we want because it blackholing all traffic, we want RTBH at Layer 4 level where ...
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1answer
30 views

Strange BGP routing issue between two public routers. Not able to see subnets

Having a strange issue can't seem to figure out what's happening. I got 2 routers running BGP. Router A is advertising 23.128.128.0/24 subnet and Router B is advertising 23.128.129.0/24. Routing is ...
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1answer
30 views

JunOS iBGP session not establishing

I have a test environment set up with two Juniper vSRX instances and a L2 network trunked between them and can reach each other on the IP addresses I'm trying to peer them on. vSRX 1 has an external ...
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32 views

How to configure Check Point Firewall BGP and OSPF?

I Need assistance with configuring BGP on a Check Point firewall. It receives only the default route, and I want to redistribute that into OSPF. If the circuit goes down, then default route is ...
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2answers
108 views

Can we have multiple AS number in the same router?

Is it possible to have multiple AS number in the same router? Example: Routing-Instance A for AS100 and Routing-Instance B for AS200 ? Please share me some example or configuration.
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2answers
49 views

Leak default route to multiple VRFs while keeping VRFs isolated from each other

I'm working on a configuring stuff on a Cisco Nexus 3k based platform and trying to isolate different things into different VRFs which should not be able to talk to each other. Some of these VRFs ...
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2answers
41 views

Using a Public AS Number Internally

We have BGP between our network and our customers networks and so far each connection uses private AS numbers (on our end we use a different AS number for each connection) We recently got a public AS ...
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1answer
42 views

how to select the most optimized BGP Anycast combination with BGP as-path prepending

The question as following: Suppose I have 3 POP (Points of Presence) points, they have the same IP address and located at different countries, such as: USA, Japan, England. The three countries serve ...
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2answers
57 views

BGP new subnet announcement

I have above scenario where I got public IP subnet got from ISP 74.100.100.0/23 and i have configured eBGP and iBGP as you can see in diagram, I have configured those Public IP in HSRP my LAN side. ...
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39 views

mp_reach_nlri bgp Update with 4-byte Community ASN?

I am BGP peering with a Juniper OS router. When starting the connection, my system advertises 4-byte ASN capability, which is accepted by the Juniper router: Jul 28 00:33:00.664202 BGP RECV 4 Byte ...
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1answer
120 views

Max AS path to accept from peer?

I heard that once AS receives a BGP update that is longer than 50, it will be dropped. Is this true or just happens with some ISPs specifying that policy? I cannot find any evidence or official ...
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1answer
88 views

ISP lab GNS3 - BGP route exchange

I'm trying to develop an understanding of the WAN/ISPs. Eventually I'll build up to MPLS, but for now I'm trying to lab up a notional, basic ISP: R1, R2, and R4 are PE routers. They've successfully ...
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1answer
89 views

Thousands of open BGP ports at some organisations - Is there a reason for this?

I hope this is the right place to ask this, but I've been browsing Shodan in the hope of gaining some insight as to how many services my organisation has that are externally accessible so I can work ...
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2answers
90 views

BGP source base routing question

This question is little convoluted to explain but i will try my best, I have following scenario. I have one ISP and i am getting 2x40G drops which you can see in diagram Link-A and Link-B (Both ...
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1answer
137 views

How to announce network to specific neighbor peer in BGP

I have following scenario where i already have 10G (A - BLUE Link) connectivity from ISP on SW1 and SW2 for redendency and i have configured eBGP and iBGP, Everything is good at this point, Now my ...
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1answer
193 views

AWS direct connect BGP issue

This is out current setup and everything working great!!! here, now i want backup link for AWS so i have request for one more secondary link and terminated on Cisco ASA on Port-channel1.8 interface. ...
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1answer
73 views

Why Connected Routes are not shown as RIB failure in BGP Table?

I know that “RIB failure” in a “show ip bgp” output indicates that a route offered to the RIB by BGP has not been accepted. But why then the connected Routes that are being advertised by the BGP ...
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1answer
71 views

Redundant internet connection with multiple lte modems

Hy i wan't to build a Redundant Internet Gateway to use multiple usb LTE Modems with diffrent SIM Cards. The goal of this is to install it on a Boat in a medium sized lake. The boat route is along the ...
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1answer
28 views

Edit BGP on IOS XE3

i need to edit my BGP Running , and add more Neighbor but when try this FiberISP-Cisco(config)#router bgp 203725 BGP is already running; AS is 203735 FiberISP-Cisco(config)# how to edit and add ...
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1answer
62 views

Why does source RTBH need uRPF

I'm trying to understand why source-address RTBH needs to be coupled with configuring uRPF on the edge ports. I've read RFC5635 and other vendor papers on this topics but I can't figure out the ...
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1answer
36 views

Traffic Destined to X Should Bypass a Certain AS Y

Let's say you do not want the traffic destined to your /8 prefix to traverse AS Y. How would you modify your BGP configuration to do that? Thank you for your time
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1answer
74 views

In what conditions an AS is triggered to broadcast BGP withdrawal message?

I'm not very familiar with the mechanism of withdrawing BGP announcements so welcome any comment. Assuming AS1 broadcasted to AS2 an AS path to its prefix and AS2 forwarded that announcement to the ...
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1answer
110 views

Question about BGP peering with your ISP

In you case you want to get rid of the static default route and you want to peer with your single ISP, do you need to announce any routes for your side ? I have the below config, is it enough for ...
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1answer
67 views

What is the preferred way to prevent a particular subnet from being sent to one ASN

I have the following network. I want to prevent Subnet 2, S2, from being routed outbound of ISPA (preferring ISPC is also acceptable). None of my ISPs use BGP communities. Given that this is a live ...
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3answers
82 views

Can SDN controllers inject or delete routes in a router?

I have seen that some SDN controllers implement a BGP plugin in their architecture (for instance, Opendaylight). But, since controllers do not sent or route packets, I wonder how and if they can ...
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1answer
74 views

Router BGP Next Hop

Why is the first Route preferred? IS there a logical reason?
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2answers
82 views

Hot Potato, algorithm of selecting route in router

I want to understand a "hot potato" principle. Given a router with 5 interfaces. The first interface gets a packet and has to decide to which interface this packet should be forwarded. I think the ...
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2answers
108 views

How does a route-map applied as outbound on a neighbor sees the redistributed ospf routes into bgp? Local or external?

Here's my scenario: Redistribute ospf routes into bgp Create a route-map that matches on route-type=local and modifies the nexthop (to 4.4.4.4 for example) Assign this route-map as outbound routemap (...
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1answer
61 views

range of AS numbers which are given out by RIRs

I need to have a range of AS numbers which are allocated by RIRs/NIRs. I guess it is every number from 0 to 2^32 except those below: 0 - reserved ASN 23456 - ...
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1answer
102 views

BGP route dampening

Does BGP dampening need to be configured on both ends of neighbor ships? Will it work if I only enable it on my end and not on the ISP end?
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2answers
71 views

VLans on small sites with no core switch

I have several small sites that are part of an MPLS network. Most of the sites have Cisco 1921 routers that are handing out DHCP for about 6 machines. Looking to add VOIP at these sites and thought ...
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2answers
93 views

can we do bgp route in cisco 2821 router?

I have a cisco2821 router and it has connected to one Internet service provider. Now i need to buy another one router so that i can have another Internet provider which can help me when one primary ...
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1answer
51 views

One AS, Multiple Site with different physical location and ISP, different prefix

I am looking to implement few servers at different location with own ASN having prefix of PI resources of /22 going to divide into 2 x /23. I am unaware of what challenges I can face. As the 2 sites ...
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1answer
160 views

BGP with OSPF configuration question

ISP - Sending default route to sw1/2 via eBGP sw1 - config router ospf 100 network 0.0.0.0 255.255.255.255 area 0 default-information originate always ! router bgp 100 bgp log-neighbor-...
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1answer
56 views

Regarding Infrastructure and Hardware

I am completely new to network engineering. So, I need some help to understand the things. I want to colocate my server with the datacenter with my own IP and ASN, do I have to have a router or a ...
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1answer
66 views

Routing the same prefix to different destinations on the same router

I have a Cisco Nexus 7000 and have configured static routes to reach my internal networks on the Nexus 7000. During a DDOS attack, the Nexus 7000 receives a more specific route via IBGP to re-route ...
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2answers
2k views

Difference between default route, partial and full routing table for a BGP session

What is the difference between default route, partial and full routing table for a BGP session? Does it affect the routes bird (or another BGP client connected to the session) sees?
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1answer
101 views

Regarding as-path-access-list

On the given router, my objective is to configure as-path-access-list so it doesn’t accept any prefixes originated by AS 1. Below are the command outputs: Coarse#sho ip bgp BGP table version is 7, ...
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1answer
42 views

Redistribution VLSM networks to BGP neighbour with summarized 24 bit mask network

I received public BGP AS with network with 24 bit mask. Is it possible, to advertise on BGP router VLSM networks summarized to 24-bit mask (not for class membership)? Example: I receive 112.112.112....
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2answers
362 views

Learned eBGP routes are advertised to iBGP neighbors but can't ping the loopback who's IP is configrued

I have a setup in my GNS3 where I am trying to understand some basic iBGP and eBGP concepts. Please refer to the diagram (I only took a screenshot of the part which is really required). I have ...
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1answer
210 views

Struggling inbound and outbound traffic engineering to/from iBGP peers at different POPs

We are a managed service provider running a small sized network in a single datacentre in Sydney. We've recently deployed a new POP inter-state in Melbourne (both are on the east coast of Australia), ...