Router on Aaron's Worthless Words

Junos - Logical Tunnel Interfaces with Virtual Routers

Sat, 02 Mar 2013 00:00:00 +0000

There are a few ways to leak routes in and out of virtual routers in Junos. On the list is a cool feature called the logical tunnel interface.

So, what am I talking about? One way to separate traffic on a router is to use virtual routers (VRs) so that you wind up with multiple routing tables on the same router. This separate traffic, but you will usually (read: always) have a demand to get traffic from one VR to another. There are a few different way to do that (see rib-group, instance-import, next-table, et al.), but one really cool way to do it is through logical tunnel interfaces.

CME Exercise #1

Thu, 07 Oct 2010 00:00:00 +0000

I tried something like this earlier this year with STP. It got rave reviews (from my mother), so I figured I try it again.

Below is a list of requirements for configuring a router as a call processor. In a lab or in your head, configure the router to support the features as listed. This isn’t a contest or anything like that. If you get it right, a virtual thumbs up is all I can afford to give you. There are some licensing issues for running this stuff in GNS3/dynamips, so I can’t help you out on that. I’ll just hint that GNS3 and dynamips will bind to real networks and that copies of a compatible IP softphone are available.

IIUC Notes - Voice Ports and Dial Peers

Mon, 04 Oct 2010 00:00:00 +0000

More of my IIUC study notes. As always, feel free to correct. I really need to have a real post, don’t I?

show voice port summary

Shows the voice ports available for use

R1#show voice port summary
                                          IN       OUT
PORT           CH   SIG-TYPE   ADMIN OPER STATUS   STATUS   EC
============== == ============ ===== ==== ======== ======== ==
50/0/1         1      efxs     up    up   on-hook  idle     y
50/0/1         2      efxs     up    up   on-hook  idle     y
50/0/2         1      efxs     up    up   on-hook  idle     y
50/0/2         2      efxs     up    up   on-hook  idle     y
50/0/3         1      efxs     up    up   on-hook  idle     y
50/0/4         1      efxs     up    up   on-hook  idle     y
50/0/5         1      efxs     up    up   on-hook  idle     y

An ephone-dn shows up as efxs, so all these are ephone-dns.
Channels are numbered 0-23; timeslots are numbered 1-24

FXS Ports

IIUC Notes - More Phone Features

Sat, 02 Oct 2010 00:00:00 +0000

Here are some more notes from my IIUC studies. As always, corrections requested.

Paging

Broadcasts messages to a group for a one-way communication
Paging groups are used to limit which phones get the broadcast
Paging can be unicast or multicast
- Unicast groups limited to 10 members
- Multicast requires mcast support on the network
Paging configurations can be unicast, multicast, or multiple-group

! Unicast Paging
! When 1044 is dialed, ephone 1 is paged
R1(config)#ephone-dn 44
R1(config-ephone-dn)#number 1044
R1(config-ephone-dn)#paging
R1(config-ephone-dn)#exit
R1(config)#ephone 1
R1(config-ephone)#paging-dn 44

IIUC Notes - Phone Features

Fri, 01 Oct 2010 00:00:00 +0000

Here are some more notes from my IIUC studies. As always, corrections requested.

Local Directory

Allows users to look up names
Allows names to show up when dialing or receiving a call
Most phones have a directory button; some have a menu options for the directory

R1(config)#ephone-dn 1
R1(config-ephone-dn)#name Roger Smith

Directory entries can be added manually

R1(config-telephony)#directory entry 1 1700 Corporate Fax
R1(config-telephony)#directory entry 2 1701 HR Fax

By default, sorting is done alphabetically by first name.
Sorting can be changed

R1(config-telephony)#directory last-name-first

IIUC Notes - Getting Phones on the LAN

Thu, 30 Sep 2010 00:00:00 +0000

More study notes. Correct if wrong, though I hope I get some of it right since I already since I’m an R&S guy. :$

**Switchport Configuration
**

switchport mode access: This config makes the port an access port that carries the primary and voice VLAN traffic
switchport mode trunk: This config akes the port a trunk unconditionally, but it will still send DTP messages
switchport nonegotiate: This config keeps the port from sending DTP messages.
switchport mode dynamic auto: If the port receives DTP messages, it will become a trunk. If not, it will be an access port.
switchport mode dynamic desirable: The port actively sends DTP messages trying to become a trunk. This is the default configuration on a Cisco switch.

Cisco IP Phone Boot Process

Stubby Post - What's an IDB?

Fri, 03 Sep 2010 00:00:00 +0000

I posed the philosophical question on Twitter the other day asking if single trunk links should be in an EtherChannel bundle just in case you need to expand later. I didn’t really expect an answer, but the ever-verbose @WannabeCCIE pointed out (in not so many words) that you should watch your IDBs. What is that?

That’s an interface descriptor block. I admit that I’m not intimately familiar with them, bu they’re data structs in IOS used to keep track of the interfaces on that device. They come in two flavors - hardware and software. HWIDBs usually represent a physical interface but they also represent tunnels, SVIs, PortChannels, subinterfaces, and any other virtual interface that you can configure. The SWIDBs represent the layer-2 encapsulation of each HWIDB, so you’ll see entries talking about Ethernet, HDLC, PPP, etc. That means that every interface you have on a router consumes two IDBs (there are always exceptions). That’s important because each platform and IOS version combination has a limit to the number IDBs that device supports.

Using SSH to Run Commands on a Router or Switch

Thu, 30 Apr 2009 00:00:00 +0000

SSH is more than just a shell. You can copy files from and to a server or piece of network gear with it. You can use it to tunnel traffic. Possibly my favorite, though, is to use SSH to run a command on a remote box without interacting with a shell.

One of my biggest pet peeves with IOS (or pretty much any Cisco OS) is the lack of complex filtering. Let’s say I want to look at all the downed ports and interfaces on modules 3 and 6 of my 6509. I can’t easily do that with command from the IOS, but, on my Linux box, I can use multiple grep commands to get exactly what I want really easily. Let’s work through the example, shall we?