New Year - New Posts!

How long is it since I've posted!

A lot has happened since my CCDP Arch posts. I passed my CCDP - Yey! I've re-certified all my Cisco certs with a last gasp effort last autumn whilst the counter to the 4th November (expiry day) was counting down.

It took me 3 attempts to clear the CCNP - ROUTE , with a week to go, which brings my routing up to date given my last routing exam was the BSCI.

2020 marks my first time at Cisco Live as well. Really looking forward to Barcelona on the 27th and I'll be adding a few posts around my experiences as a first timer.

Finally I'm intending on picking up the ENCOR study material and get my self prepared for the CCIE lab - eek! - Not sure if I'll clear it but what the hell, I'll pick up a load of skills on the way.

Good luck in your NetworkStudies folks!

CCNP - ENTERPRISE - DESIGN - Command Reference

This article looks to collect together the most frequent commands associated with the CCDP ARCH exam.

The point being that these are easy marks to pick up on the exam when you get a question such as 'Name the command that allows you to [insert task here]'

This list is by no means complete and I'll add further commands as I find them.

OSPF - Originate a default route in to OSPF
    #router ospf 10
        #default-information originate [always]

OSPF - On the ABR filter out all advertised routes accept those listed in the range command
Limits the size of the DB and reduces the flooding internally
    #router ospf 1
         #area 20 range 192.168.200.0 255.255.255.0

OSPF - On the ASBR filter routes sent out externally to those explicitly listed.
    #router ospf 20
         #summary address [prefix] [mask]

OSPF - Tune the OSPF hello timer interval for faster convergence
    #interface f0/0
        #ip ospf hello-interval [seconds]

OSPF - tune SPF timers to increase efficiency
    #conf t
          #timers throttle spf [spf-start] [spf-hold] [spf-max-wait]

OSPF - Increase the reference bandwidth to factor in high speed link such as 10GB ethernet, do this across all links for consistency
    #router ospf 20
          #auto-cost reference-bandwidth 10000 (for 10Gb ethernet links)

EIGRP - Originate a default route in to EIGRP
    #conf t
         #ip default-network [network ip]

EIGRP - configure unequal-cost load balancing
    #router eigrp 1
       #variance 2

BGP -configure neighbor as a Client of the route reflector
    #router bgp 65123
        #neighboor 1.1.1.1 route-reflector-client

IPv6 - enable IPv6 routing for use with RIPng, EIGRP for Ipv, OSPFv3 etc
    #conf t
         #ip v6 unicast-routing

IPv6 - Define a base prefix to use for addressing:
  #conf t
       #ipv6 general-prefix [prefix]

CEF - Eliminate CEF Polarisation where one redundant link ends up being preferred to the other
    #conf t
         #mls ip cef load-sharing

EtherChannel - Use this to ensure all links within an Etherchannel bundle are utilised effectiviely
    #conf t
        #port-channel load-balance src-dst-port

FlexLinks  - Configure a port to act as a resilient backup for FlexLinks. Configure this on the primary link.
    #interface f0/10
       #switchport backup-interface [interface id]

CCNP - ENTERPRISE - DESIGN - Well Known Multicast Addresses

In the CCDP ARCH exam there are numerous refereences to Multicast addresses.

This post is to simply catalogue those that are specifically refered to in the various reading materials I've covered.

Address Scope:

• 224.0.0.0 /4 - Class D reservation

Address type:

• 224.0.0.0 to 224.0.0.255 - assigned by IANA for services (detailed below)
• 224.0.1.0 to 224.0.1.255 - Control Block - assigned by IANA for traffic crossing public networks e.g.- NTP 224.0.1.1
•  224.0.2.0 to 224.0.255.255 - AD-HOC block assigned by IANA for addresses that don't fit the above ranges
• 224.3.0.0 to 224.4.255.255 - AD-HOC block assigned by IANA for addresses that don't fit the above ranges
• 233.252.0.0 to 233.255.255.255-  AD-HOC block assigned by IANA for addresses that don't fit the above ranges
• 232.0.0.0 255.0.0.0 - Source-Specfic Multicast Addresses
• 233.0.0.0 255.0.0.0 - GLOP addresses - Originally experimental now publically assigned addresses for use by ISPs and any organisation want to ublich content over Multicast
• 234.0.0.0 255.0.0.0 - Uni-cast Prefix addresses
• 239.0.0.0 255.0.0.0 - Administratively scoped IPv4 addresses, locally assigned, not globally unique

Well Known Addresses:

224.0.0.1 The All Hosts multicast group addresses all hosts on the same network segment.

224.0.0.2 The All Routers multicast group addresses all routers on the same network segment.

224.0.0.5 The Open Shortest Path First (OSPF) All OSPF Routers address is used to send Hello packets to all OSPF routers on a network segment.

224.0.0.6 The OSPF All Designated Routers ""(DR)"" address is used to send OSPF routing information to designated routers on a network segment.

224.0.0.9 The Routing Information Protocol (RIP) version 2 group address is used to send routing information to all RIP2-aware routers on a network segment.

224.0.0.10 The Enhanced Interior Gateway Routing Protocol (EIGRP) group address is used to send routing information to all EIGRP routers on a network segment.

224.0.0.13 Protocol Independent Multicast (PIM) Version 2

224.0.0.18 Virtual Router Redundancy Protocol (VRRP)

224.0.0.19 - 21 IS-IS over IP

224.0.0.22 Internet Group Management Protocol (IGMP) version 3

224.0.0.102 Hot Standby Router Protocol version 2 (HSRPv2) / Gateway Load Balancing Protocol (GLBP)

224.0.1.1 Network Time Protocol clients listen on this address for protocol messages when operating in multicast mode.

224.0.1.39 The Cisco multicast router AUTO-RP-ANNOUNCE address is used by RP mapping agents to listen for candidate announcements.

224.0.1.40 The Cisco multicast router AUTO-RP-DISCOVERY address is the destination address for messages from the RP mapping agent to discover candidates.

224.0.1.41 H.323 Gatekeeper discovery address

239.255.255.250 Simple Service Discovery Protocol address

CCNP - ENTERPRISE - DESIGN - Spark's rules for Design

During my studies I've noticed common themes in how to approach network design.

In general I've found that it comes down to making the best of what you've got (unless you're Google and simply commission your own hardware and build your very own private internet - coming to home near you soon...)

Based on that I've noted the following observations during my studies:

• Divide and Conquer! - Large flat networks are generally a bad idea, they propagate all the broadcast/multicast traffic to all hosts, make poor use of available network resourse (bandwidth, increase work on routers/firewalls etc),  are difficult to scale, increase the impact of a network event across the environment. Where possible segment it. For example:
• OSPF - Make use of backbone routers in Area 0 and then use different areas to limit the propagation of Link State Advertisiements. In doing this you reduce the amount bandwidth used up by the OSPF process, you reduce the about of processing load on the routers within each area and the LSA's are limited to each area (reducing the content of the Routing Table). Originate the Default Route from Area 0 and where possible make use of Stub, Totally Stubby and Not-So-Stubby-Areas to reduce LSA/Route propagation.
• Campus Design - Make good use of Hierarchical designs with a Core, Distribution/ Aggregation, Access Layers. These scale well, limits broadcast domains and make troubleshooting more logical
• IP Address Assignment - Use contiguous networks and avoid any discontiguous subnets. Contiguous subnets makes address assignment easier (more efficient allocation of address space), troubleshooting easier, you can trace through the network easier, allows for efficient route summarisation and redistribution.
• Summarise it! - Expanding on the previous point, when advertising routes, where possible advertise summary routes for destinations in a given area/zone. By advertising a summarised route you are reducing the size of routing tables on upstream routers and you then limit the impact of route flaps within the network. If a single link goes down then a route that is advertised as a /30 would need removing from all routers that have a route for this network. If the failed link falls under a /24 route then the upstream routers don't observe the link flap and do not have to re-calculate the shortest path which inturn means that resources on upstream routers are not utlised unneccesarily.
• Keep It Simple! - At the dead of night that on call network engineer will not thank you for building that convoluted network that makes use of lesser know commands just because it's fancy. Always consider how difficult troubleshooting the proposed solution will be and keep it simple. For example:
• Avoid OSPF virtual links - an network outage in the transit area could cut off the remote area to area 0
• Keep access lists consistent - Agree on a naming convention for access lists, object-groups, hosts. Agree on how an access list will be named and how it will be constructed and stick to it. Being consistent will make for a cleaner running-config and will make reading it easier which in turn should make troubleshooting easier

Now, the point of the rules above is to apply each rule as measure of how to approach exam questions. For any given question can the rules above be applied and the correct answer revealed? (Of course you should know your stuff when it comes to sitting an exam but sometimes you get blind sided by a badly worded question)

Remember to be methodical and ultimately consider What Would Cisco Do...?

Well Known Ports

The full range of available ports is 0 - 65536 and can be used dynamically by any application however in general ports 0 - 1024 are pre-defined and 'well known' which is to say 22 is always ssh, 80 is http and so on.

Port Number	Description
1	TCP Port Service Multiplexer (TCPMUX)
5	Remote Job Entry (RJE)
7	ECHO
18	Message Send Protocol (MSP)
20	FTP -- Data
21	FTP -- Control
22	SSH Remote Login Protocol
23	Telnet
25	Simple Mail Transfer Protocol (SMTP)
29	MSG ICP
37 39	Time RIP
42	Host Name Server (Nameserv)
43	WhoIs
49	Login Host Protocol (Login)
53 67 68	Domain Name System (DNS) bootps bootpc
69	Trivial File Transfer Protocol (TFTP)
70	Gopher Services
79	Finger
80 88 101 102	HTTP Kerberos Hostname iso-tsap
103 107	X.400 Standard rtelnet
108	SNA Gateway Access Server
109	POP2
110 111 113	POP3 sunrpc auth
115 117	Simple File Transfer Protocol (SFTP) uucp-path
118	SQL Services
119 123	Newsgroup (NNTP) NTP - Network Time Protocol
137	NetBIOS Name Service
139	NetBIOS Datagram Service
143	Interim Mail Access Protocol (IMAP)
150	NetBIOS Session Service
156	SQL Server
161	SNMP
179	Border Gateway Protocol (BGP)
190	Gateway Access Control Protocol (GACP)
194	Internet Relay Chat (IRC)
197	Directory Location Service (DLS)
389	Lightweight Directory Access Protocol (LDAP)
396	Novell Netware over IP
443	HTTPS
444	Simple Network Paging Protocol (SNPP)
445	Microsoft-DS
458	Apple QuickTime
546	DHCP Client
547	DHCP Server
563	SNEWS
569	MSN
1080	Socks

Output Characters from PING

This table is taken from the following Cisco article:
Understanding PING and Traceroute Commands

The table below lists the possible output characters from the ping facility:

Character	Description
!	Each exclamation point indicates receipt of a reply.
.	Each period indicates the network server timed out while waiting for a reply.
U	A destination unreachable error PDU was received.
Q	Source quench (destination too busy).
M	Could not fragment.
?	Unknown packet type.
&	Packet lifetime exceeded.

And I just want to log this here for quick reference. Thanks

Download a Packet Capture from an ASA

Firstly run your capture:
1) create an access list that will match the packets you are interested in seeing e.g:
    #access-list TESTCAP extended permit tcp 10.10.10.0 255.255.255.0 host 10.10.10.254 eq ldap

2) Create the capture on your ASA:
   #capture TESTCAP access-list TESTCAP interface INSIDE

Let that run then once you have collected enough data (use sh capture TESTCAP to view the capture ) transfer the capture file (pcap) to your local machine to view in a packet analyser programme such as WireShark:
1) Download and install a TFTP server programe (I used Solarwinds TFTP server) and then start the server.
2) From the firewall concerned run change to the System Context then run the following :
    #changeto context system
    #copy /pcap capture:[ContextName]/TESTCAP tftp:
    You will be asked for the destination IP - this will be your laptop IP that is running TFTP
    Note - [ContextName] should be the name of the context that the capture is running on.
3) Check the TFTP-root folder on your local machine to verify the transfer was successful.
4) Open WireShark then open the pcap file from there.

View the Pre-Shared Key on an IPsec VPN tunnel-group

When troubleshooting VPN connectivity issues a common problem is a mis-matched pre-shared key.

When you add a pre-shared key to a tunnel-group if you issue a #sh run the output hides the key with a simple *. e.g:

tunnel-group 10.10.10.10 ipsec-attributes
 pre-shared-key *
 isakmp keepalive threshold 15 retry 2

To confirm precisely what has been applied (and therefore help confirm if both ends of your tunnel have the same key) use the following command:
 #more system:running-config

tunnel-group 10.10.10.10 ipsec-attributes
 pre-shared-key AbCdEfG192837645
 isakmp keepalive threshold 15 retry 2

Upgrade the IOS on a Cisco Catalyst 3750 switch

Steps to conduct an upgrade of the IOS are as follows:

1. Download the new image from www.cisco.com using a suitable account
2. Install a TFTP server such as SolarWinds TFTP Server (other TFTP programs are available)
3. Boot the switch and apply an IP address to the VLAN1 interface
4. Apply an IP in the same subnet to your PC/Laptop LAN port and cable up using a CAT5 straight through
5. Ping both sides to confirm connectivity
6. Copy the downloaded BIN image to the TFTP-Root folder you'll find on the C:drive
7. Start the TFTP Server on the PC/Laptop
8. On the switch back up the current image to your PC/Laptop #copy Flash:/[filename.bin] tftp
9. Enter the required remote host IP and confirm the destination file name when prompted
10. Allow the current file to copy over to the PC/Laptop
11. Once complete delete the original from the switch to create space for the new image #delete /recursive Flash:/[filename.bin]
12. Next copy the new image from the PC/Lpatop to the switch #copy tftp: flash:
13. Enter the remote host details and file name then confirm
14. Allow the file to copy
15. Set the new BIN as the system boot image #boot system flash:/[filename.bin]
16. write this #wr
17. Reload

Verify the image in use via - #sh ver

VPN - QM FSM error and PFS

We're busy attempting to bring up a site to site IPSec tunnel to Cisco router from our ASA.

Phase1 is completing but Phase2 fails with a 'QM FSM Error'.

This very unhelpful error message results from PFS not matching at either end. Either set it or don't set but if you have one end configured and the other not then you'll get an error like the one above.

Check the config on both ends of your VPN and either add PFS or remove by entering the following:
[no] crypto map VPNCONNECTION set pfs [group1 | group2 | group 5 ]

Notes:

• PFS must match at either end
• The default action on an ASA is to be off
• If you just enter 'set pfs' and don't define a group then group1 is offered by default and group1/group2 is accepted
• If you set the group then the same group must be returned by the remote peer.