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Posts tagged HowTo
BGP Backdoor Lab
Nov 12th
In this article we’ll be going over the BGP Backdoor feature. This is used in cases where two systems are connected via an IGP, but also receiving routes to the same system through BGP. I stumbled across this feature while checking out one of the labs on Darren’s Blog. The only way I could think of to complete one of his criteria was changing the Administrative Distance of either BGP or the IGP. That is essentially what this feature does, but on a route-by-route basis instead of changing the AD of an entire protocol. I asked Darren if that was the only solution and he pointed me to “BGP Backdoor”. As usual, I will be including my Dynagen/GNS3 .net file at the end of this post. Here is our topology:
Let’s go through the config:
R1
hostname R1 ! interface Serial0/0 ip address 10.1.1.1 255.255.255.0 ! interface Serial0/1 ip address 10.1.3.1 255.255.255.0 ! router bgp 65000 no synchronization bgp log-neighbor-changes neighbor 10.1.1.2 remote-as 65525 neighbor 10.1.3.2 remote-as 65535 no auto-summary |
NetFlow Top-Talkers
Nov 2nd
This is a short article on the NetFlow “top-talkers” CLI feature, which I didn’t know about before today. NetFlow is a tool for monitoring traffic flows, it’s particulalry handy when you’re trying to find out what host or protocol is saturating a network. Obviously the pretty GUI NetFlow collectors are better for many things, but the CLI method can be really helpful if you’re looking for something quickly. Here’s the config:
Here’s the config from my outside interface.
interface FastEthernet0/0 description OUTSIDE ip address xx.xx.29.218 255.255.255.248 ip flow ingress ip flow egress |
I’ve enabled NetFlow with the “ip flow” commands.
Here are the commands to enable the “top-talkers” feature at the CLI.
EDGE(config)#ip flow-top-talkers EDGE(config-flow-top-talkers)# top 25 EDGE(config-flow-top-talkers)# sort-by bytes EDGE(config-flow-top-talkers)# cache-timeout 5000 EDGE(config-flow-top-talkers)#^Z |
Pretty simple, we’ve set how many conversations to show, then we can sort by bytes or packets, finally we set our timeout (in milliseconds).
Now we’ll look at the show command:
EDGE#sh ip flow top-talkers SrcIf SrcIPaddress DstIf DstIPaddress Pr SrcP DstP Bytes Fa0/1 xx.xx.29.221 Fa0/0* 212.84.105.94 06 F6B9 9C40 77K Fa0/1 xx.xx.29.218 Fa0/0* 66.194.235.133 06 01BB EF24 12K Fa0/1 xx.xx.29.221 Fa0/0* 85.24.163.125 06 7F23 EC43 10K Fa0/1 xx.xx.29.221 Fa0/0* 114.89.235.172 06 7F23 0CB7 9216 Fa0/0 72.211.212.180 Fa0/1 xx.xx.29.221 06 EC74 7F23 5088 Fa0/0 66.194.235.133 Fa0/1 xx.xx.29.218 06 EF24 01BB 2680 Fa0/0 121.127.209.73 Fa0/1 xx.xx.29.221 06 0E20 7F23 2297 Fa0/1 xx.xx.29.221 Fa0/0* 121.127.209.73 06 7F23 0E20 2162 Fa0/0 87.194.215.124 Fa0/1 xx.xx.29.221 06 C220 7F23 2100 Fa0/1 xx.xx.29.221 Fa0/0* 87.194.215.124 06 7F23 C220 2072 Local xx.xx.29.218 Fa0/0* 70.71.239.87 32 033B B7EC 2000 Fa0/0 88.193.80.142 Fa0/1 xx.xx.29.221 06 D788 7F23 1838 Fa0/1 xx.xx.29.221 Fa0/0* 88.193.80.142 06 7F23 D788 1832 Fa0/1 xx.xx.29.221 Fa0/0* 70.64.13.242 06 7F23 F5BC 1717 Fa0/0 212.84.105.94 Fa0/1 xx.xx.29.221 06 9C40 F6B9 1276 Fa0/0 70.64.13.242 Fa0/1 xx.xx.29.221 06 F5BC 7F23 1067 Fa0/1 xx.xx.29.218 Fa0/0* 74.125.67.149 06 1853 0050 872 Fa0/1 xx.xx.29.221 Fa0/0* 217.145.245.245 06 7F23 8736 868 Fa0/0 70.177.163.148 Local xx.xx.29.218 2F 0000 0000 816 Fa0/0 24.11.68.215 Fa0/1 xx.xx.29.221 06 DABF 7F23 767 Fa0/0 81.234.172.49 Fa0/1 xx.xx.29.221 06 08A8 7F23 617 Tu103 xx.xx.29.218 Fa0/0* 65.120.117.126 32 0CED D9C9 616 Fa0/0 74.125.67.149 Fa0/1 xx.xx.29.218 06 0050 1853 594 Fa0/1 xx.xx.29.221 Fa0/0* 81.234.172.49 06 7F23 08A8 499 Fa0/0 85.68.237.69 Fa0/1 xx.xx.29.221 06 1F37 C0E5 372 |
ODR Lab
Oct 31st
In this article we’ll do a short ODR (On Demand Routing) lab. ODR is a simple routing protocol targeted at hub and spoke topologies, it uses CDP to propagate routing updates. This is one of the technologies that might be on the CCIE exams. I will be including my Dynagen/GNS3 .net file at the end of this post. Here is our topology:
Let’s go through the config:
R1
hostname R1 ! interface Loopback0 ip address 1.1.1.1 255.255.255.255 ! interface Serial0/0 ip address 10.1.0.1 255.255.255.252 ! interface Serial0/1 ip address 10.1.1.1 255.255.255.252 ! interface Serial0/2 ip address 10.1.2.1 255.255.255.252 ! router odr |
We configure the hostname and our Loppback and Serial interfaces. The important command here is “router odr”, this turns ODR on. This command is ONLY run on the hub.
R2:
hostname R2 ! interface Loopback0 ip address 2.2.2.2 255.255.255.255 ! interface Serial0/0 ip address 10.1.0.2 255.255.255.252 |
R3:
hostname R3 ! interface Loopback0 ip address 3.3.3.3 255.255.255.255 ! interface Serial0/0 ip address 10.1.1.2 255.255.255.252 |
R4:
hostname R4 interface Loopback0 ip address 4.4.4.4 255.255.255.255 ! interface Serial0/0 ip address 10.1.2.2 255.255.255.252 |
We now have our hostnames and interfaces configured on R1, R2 and R3. Notice we DO NOT use the “router odr” command on the spokes.
Surprisingly, that is all there is to it! Let’s verify our config:
Basic AToM Lab
Oct 14th
In this article we’ll go over a simple AToM (Any Transport over MPLS) configuration. I’ve been studying MPLS a lot lately and this is my first time playing with AToM and it’s very cool stuff. This article could be useful for anyone studying MPLS and/or CCIP/CCIE topics, or just someone who is interested in learning new things. I will be including my Dynagen/GNS3 .net file with this. Here is our topology:
Let’s go through the config:
P Router:
hostname P ! mpls label protocol ldp mpls ldp router-id lo0 force ! interface Loopback0 ip address 1.1.1.1 255.255.255.255 ! interface FastEthernet1/0 ip address 10.1.1.1 255.255.255.252 duplex auto speed auto mpls ip ! interface FastEthernet1/1 ip address 10.1.2.1 255.255.255.252 duplex auto speed auto mpls ip ! router ospf 100 router-id 1.1.1.1 log-adjacency-changes network 1.1.1.1 0.0.0.0 area 0 network 10.1.1.0 0.0.0.3 area 0 network 10.1.2.0 0.0.0.3 area 0 |
Here we’ve set the hostname, configured the MPLS label protocol (note: LDP is the default on new IOSes), we set a loopback interface that will be our RID for MPLS and OSPF. We also configured our connections to the PE routers and brought up OSPF as our IGP.
PE1 Router:
hostname PE1 ! mpls label protocol ldp mpls ldp router-id lo0 force ! pseudowire-class one encapsulation mpls ! interface Loopback0 ip address 2.2.2.2 255.255.255.255 ! interface FastEthernet1/0 ip address 10.1.1.2 255.255.255.252 duplex auto speed auto mpls ip ! interface Serial2/0 no ip address xconnect 3.3.3.3 100 pw-class one ! router ospf 100 router-id 2.2.2.2 log-adjacency-changes network 2.2.2.2 0.0.0.0 area 0 network 10.1.1.0 0.0.0.3 area 0 |
PE2 Router:
hostname PE2 ! mpls label protocol ldp mpls ldp router-id lo0 force ! pseudowire-class one encapsulation mpls ! interface Loopback0 ip address 3.3.3.3 255.255.255.255 ! interface FastEthernet1/0 ip address 10.1.2.2 255.255.255.252 duplex auto speed auto mpls ip ! interface Serial2/0 no ip address xconnect 2.2.2.2 100 pw-class one ! router ospf 100 router-id 3.3.3.3 log-adjacency-changes network 2.2.2.2 0.0.0.0 area 0 network 10.1.2.0 0.0.0.3 area 0 |
SIP Trunk With CME
Sep 28th
In this article I’ll go over how to build a SIP Trunk to a provider with Call Manager Express, in this case we’ll use Flowroute. I will be using my 3725 with IOS “c3725-adventerprisek9-mz.124-15.T10.bin”.
First we will enable SIP, then we configure the router to register with our provider, then we’ll configure our codecs and dial peer, finally we’ll go over some show commands to verify that everything works.
Here’s how to enable SIP:
voice service voip sip |
Very simple, we just enable the SIP protocol.
Next we configure our router to register with Flowroute:
sip-ua authentication username xxxxx password 7 xxxxxxxxxx realm sip.flowroute.com calling-info pstn-to-sip from number set 1xxx7325736 no remote-party-id registrar dns:sip.flowroute.com expires 3600 |
This tells the router to register with “sip.flowroute.com” using the username and password we specified.
Next we configure our codecs:
voice class codec 1 codec preference 1 g729r8 codec preference 2 g711ulaw codec preference 3 g711alaw |
Here we specify which codecs we want to use and what order we prefer them, 1 being most preferred and 3 being least preferred. I have chosen to use g729 whenever possible as it needs much less bandwidth and sounds great.
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