Questions tagged [routing]

For questions about routing, the process of selecting to which network path traffic is sent. Consider using a more specific tag if your question is about a routing protocol like BGP or OSPF.

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Cisco administrative distance 255

On Cisco gear the maximum administrative distance for a route is 255. This makes the route unusable. If the administrative distance is 255, the router does not believe the source of that route and ...
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4 votes
1 answer
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Why BGP choose wrong Next-hop address?

In diagram above R1 has got a loopback with 1.1.1.1/24 ip address, both R1 and R2 advertise out this network 1.1.1.0/24 to other AS using this router bgp network config: network 1.1.1.0 mask 255.255....
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1 vote
1 answer
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Uverse Can't Access One Site [closed]

I'm eight hours into this and no better off than before. My customer is a small office in a remote location, about 20 workstations and a Windows '03 server. They have been served by AT&T DSL for ...
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2 votes
1 answer
4k views

SonicWall DMZ and LAN inbound mapping

I have a question, to which I think I know the answer. I have a SonicWall TZ 215 configured and working fine with a DMZ and ports mapped through to that DMZ, but the need has come up to map traffic ...
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4 votes
1 answer
1k views

What can I use on a branch SRX cluster instead of an lt-0/0/0 interface?

Background I have the following config which uses lt interfaces to route traffic between 2 routing instances (default and a custom one called vpn). The reason I do this is so that I can have ...
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6 votes
2 answers
3k views

Maintain prefixes even when bgp peer goes down

Is there a way to maintain the BGP prefixes a router has learned from another device even when reachability to the peer drops so that bgp doesn't need to withdraw all the routes and then relearn them? ...
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6 votes
2 answers
3k views

What is an acceptable spell of total packet loss for public Internet traffic?

The context: an Internet facing web site, streaming near real-time market prices. Paying customers can be anywhere on the Internet. The issue: Customers can experience total packet loss for 10s, 30s ...
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3 votes
1 answer
6k views

Problem with VPN tunel from local network to the local VPN server

I have network situation like this: ISP Router (modem) - device given to us by our ISP - modem & router in one but it is set into transparent mode - ISP say so ;D we have to find it that it is ...
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4 votes
1 answer
270 views

Hub-Spoke topology -- L3 Links use multiple /30s vs single /24 shared?

I wanted to ask the community their thoguhts on the pros and cons of this scenario. I have a few L3 switches with their own independent VLANS connecting to a a set of stacked switches over a port-...
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14 votes
3 answers
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How broadcasting works on different networks?

I was reading DHCP ( RFC 2131 ), I have basic knowledge about Relay Agent and Broadcasting. But for Understanding DHCP in depth, I felt like I have to know Broadcasting and Relay Agent ( RFC 1542 ) in ...
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1 vote
1 answer
341 views

How can I tell which routing protocol a wifi mesh network is using? [closed]

Is there a way to determine it, maybe with some heuristic (sniffing)?
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3 votes
4 answers
3k views

Dual Stack Network Configuration

I am trying to implement Dual Stack configuration of a network in Packet Tracer. I have two routers connected to each other both of these routers have one IPv4 client and one IPv6 client. The routers ...
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7 votes
1 answer
3k views

Problem with VPN tunel from remote location through ISP (PPTP)

I have network situation like this: ISP Router (modem) - device given to us by our ISP - modem & router in one but it is set into transparent mode - ISP say so ;D we have to find it that it is ...
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5 votes
2 answers
1k views

Routing protocol for Large scale hub and spoke VPN

I'm looking at implementing a linux-based VPN setup with approx 1200 remote sites connecting into two redundant data centers/DCs. Each remote site has 4 networks, and each DC has ~10. The VPN itself ...
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2 votes
3 answers
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IPs overlaps on L3 cisco 3550 switch?

I want to configure my L3 switch to connect multiple devices: squid proxy (192.168.1.4) web server (192.168.1.6) client (192.168.1.11) something like that: the problem is when I configure one ...
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  • 341
4 votes
3 answers
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Difference between router leg and static routes

I am looking a L2/L3 switch spec. which says it supports 256 Router Legs and maximum of 32 Static routes. Can somebody explain with an example, what is the difference between router leg and static ...
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  • 419
5 votes
1 answer
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Cisco 877 ADSL Configuration

I'm a unix systems engineer and my network background is not so strong; I need a help to do the last touch-up to a cisco 877. I've substituted our adsl router (a simple home router provided by the ...
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  • 359
10 votes
2 answers
2k views

Why can't I ping from one computer to another using L3 cisco 3550 switch?

I have configured my 3550 L3 switch to redirect HTTP traffic to a significant Machine: This is my scenario ( PCs instead of Routers): This is the switch configuration: CAT3550# show running-config ...
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  • 341
7 votes
1 answer
294 views

# of bgp routes sent to neighbor drops after session reset

I have iBGP configured between two devices. After the bgp session comes up, the # of routes sent to RouterA from RouterB initially increases to roughly 100k, but then for some reason, it drops down ...
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0 votes
2 answers
250 views

A possibly weird problem

I'm not a network guy, but a system administrator by background. I find myself, now, the sole IT guy at a growing business. (This turned into a long explanation to setup the question, which is at the ...
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1 vote
1 answer
5k views

Configure DNS Table on Sonic Wall TZ205

I just installed a TZ-205 on our company network and I can not seem to find where I would add to a DNS table. On our Linksys LRT224 there is a option to add a domain name and an associated IP. Does ...
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1 vote
1 answer
2k views

Routing through a Firewall to FTP server

I currently have a small network which contains an FTP server that I'd like to be able to access from the Internet at home. This network has a firewall with 2 interfaces - 192.168.0.75 - Facing the ...
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3 votes
1 answer
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Cisco SG500X InterVLAN Routing Issue

We recently got 2 new Cisco SG500 Series Switches (1x 24p & 1x 48p in a Stack) for a location. The plan was to have the SG500X do the routing between VLANs. So we went through and got these ...
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11 votes
2 answers
3k views

Trying to fit centralised firewall into network topology

I'm in the process of over-hauling our network, the issue I keep coming back to is: trying to bring layer 3 to the core, while still having a centralised firewall. The main issue I have here is that ...
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  • 1,458
3 votes
1 answer
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L3 Switch Static Route for 2 gateway

In my network I use L3-3650x as core switch to route internal network. I have 2 internet gateways, one for local internet [192.168.2.1] and the other for Japan connection [172.17.138.1]. Both routers ...
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  • 45
2 votes
4 answers
200 views

Setting Default GW to Local IP

So I got to thinking today, as I was working on a task, that systems need to know a gateway to which to forward packets which are destined for non-local networks. Then I recalled that, in a former ...
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  • 133
10 votes
1 answer
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How does NAT share one public IPv4 address across multiple private IPv4 addresses [closed]

I think it's a very classical question, but, thought I've have some background, I don't have enough vocabulary anymore to search and understand correctly in the Web. Let's say I have a home network ...
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5 votes
1 answer
11k views

HP V1910, VLAN routing - what did I miss?

First time posting in this part of stack exchange and I'm a novice regarding advanced network configuration - plug & play switch installation I can handle ;o) I got myself a HP V1910-48G (former ...
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  • 215
2 votes
1 answer
852 views

How to virtual-link between two different OSPF areas

Is there a way to connect routers via virtual-link between two different OSPF area?
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4 votes
3 answers
6k views

Link-state routing Vs Distance-vector routing algorithm used confusion

In Link-state routing protocol Dijkstra's algorithm is used. In Distance-vector routing protocol Bellman-Ford algorithm is used. My question is why we use two different algorithm. Why not only one ...
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3 votes
3 answers
808 views

Does OSPF use a packet checksum using MD5?

When we configure OSPF routers with MD5 authentication, a message digest is created, which is the combination of a pre-defined message-digest-key which has been run through the MD5 algorithm; that ...
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  • 475
2 votes
2 answers
3k views

Does Netscaler authenticate the back-end server's certificate?

Disclaimer: I am not a network engineer but a software engineer so I may muddle my terminology, feel free to correct me where I go wrong! My understanding of our set-up is: We have a Netscaler (lets ...
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  • 123
3 votes
1 answer
1k views

How to Summarize LSA Type 7/NSSA ASBR External routes?

I have Area 0 and Area 1, Area 1 is configured as NSSA and there is this router R3 in this area that works as ASBR and redistributing/injecting some external routes from some other routing domain into ...
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  • 475
2 votes
1 answer
65 views

What could cause a previously working point to point to be accessible from only one side? [closed]

I have two sites that are connected using a pair of Motorola Canopy 5.7 Ghz backhaul units. They have been working for years without a problem but this morning we had a power outage for a few hours ...
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46 votes
8 answers
4k views

Network Neutrality, how does it actually work, technically speaking?

In this NPR article there is mentioned 'network neutrality' with very little details on what it actually is or how it actually works. I tried researching it on my own but I get a lot of non-technical ...
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2 votes
0 answers
842 views

Enabling multipath in ns2 with no rtproto DV [closed]

So I am trying to run a simulation using the MPTCP protocol in a data center but rtProto DV is not working; produces an error, I am guessing the implementations doesn't have support for it and I can't ...
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1 vote
2 answers
208 views

BGP update message burst

I am analyzing certain BGP update messages and normally, an average BGP message(withdrawal) could contain 2-3 prefixes. During my analyses, i noticed that there are some few withdrawal updates that ...
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  • 141
1 vote
2 answers
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Routing Between Cisco 4507R+E Layer 3 Switch & UTM Firewall Fortigate

Please Help me. I have a Cisco Catalyst 4507R+E and UTM Firewall Fortigate and I Created VLANS on Catalyst and the main VLAN port Which Play IP Route between All VLANs can not connectet to the UTM ...
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1 vote
1 answer
2k views

Why can the STUN server reach the client behind NAT?

In these two figures, why the 173.239.151.99(clientB) and the STUN server both know the clientA(192.168.0.1)'s public IP, why clientB can't reach clientA but STUN server can? Or to put my question ...
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  • 235
1 vote
2 answers
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Load Balancing and failover on 2 Router 2951

Point 1- Currently we have 1 ISP which is terminated on Router 2951 and now we are planning to add 1 more Router 2951 and 2nd ISP link. Need to achieve Failover and load balancing between these TWO ...
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  • 101
3 votes
1 answer
298 views

OSPF p2p Network type

Imagine this scenario: R1-------R2 R1's serial 1 is connected to R2's serial 1, it's a simple p2p link. Quite simple, right? When I changed the network type on the both sides to non-broadcast, for ...
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  • 475
2 votes
1 answer
2k views

Twice NAT destination routing on pre-translated address for Cisco ASA 8.4

I have a Twice NAT routing question. How do I forward an IP packet based on the pre-translated destination? Right now I have conflicting subnets between two sites which is why I am doing the Twice NAT....
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  • 813
1 vote
2 answers
264 views

Is there any way to send out an IP directed packet?

Is there a way to send out a packet such that its path is predetermined? Basically, I want to attach an "IP map" of how I want it to travel. If so, what are the steps? Thanks!
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  • 113
1 vote
1 answer
126 views

Our vlans can contact each other, we wan't them to not be able to

We have 2 vlans vlan 20 & vlan 30 they are both currently able to contact each other but we don't want them to be able to. We have 2 switches too, with these vlans on them. They should not be ...
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6 votes
2 answers
687 views

VLAN-Subnets 1:1?

I often hear people saying that each VLAN is a subnet (or is associated with a subnet) but is that really true? Assume I have 10 big offices. I will have a subnet for each office but only 2 VLANs ...
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  • 121
6 votes
1 answer
915 views

Does EIGRP use AS number/process number as it's PORT NUMBER between routers in the same AS/group?

Does EIGRP use AS number/process number as it's PORT NUMBER between routers in the same AS/group? I know that EIGRP does NOT use TCP/UDP; I know that that EIGRP uses RTP as a mechanism to establish a ...
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  • 475
5 votes
1 answer
1k views

why RIP sending only maximum of 512 bytes of data

When RIP router sends update to routers, why it is limited to use only 512 bytes of UDP data. Why not more than that, even when it has a 1500 byte MTU. How is the maximum of 512 bytes determined?
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2 votes
0 answers
450 views

Is there any way to view the current queue size for a BGP neighbor in the Bird routing daemon?

Using a Cisco or Juniper routers you can see the size of the output queue value by showing the bgp summary. This information is also available when showing the detailed neighbor information. e.g. ...
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5 votes
1 answer
2k views

Controlling route-map distribution with 'match interface' in EIGRP

I have a "Tun0" interface over which I speak EIGRP. On this same router I have a "Vlan1" interface. What i'd like to do is speak only of the interfaces that pass a route-map, e.g. route-map foo ...
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  • 599
2 votes
0 answers
7k views

Setup the BGP + ospf network

I've the next Lab with GNS3 I have two autonomous systems(100,200), when the AS 100 run a OSPF with two areas, 0 and 1. The AS 200 has only a router and computer, so easy. But I don't know how to ...
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