Bryan: Added info about looping

2017-09-21T23:12:13Z

Added info about looping

Bryan: P25 Network Exchange packet format

2016-10-13T02:09:14Z

P25 Network Exchange packet format

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There are three formats for the p25 network packet. All ride inside of a [https://en.wikipedia.org/wiki/User_Datagram_Protocol UDP] packet

== Version 1==

== Version 2==

== Version 3==

This is the development version of the packet and is not to be used as it's pre-standard.
This should support IPv4 unicast and Multicast transports. multicast will be the primary transport focused on.

{| class="wikitable" style="margin: 0 auto; text-align: center;"
|+IPv4 Pseudo Header Format
|-
! style="border-bottom:none; border-right:none;"| ''Offsets''
! style="border-left:none;"| [[Octet (computing)|Octet]]
! colspan="8" | 0
! colspan="8" | 1
! colspan="8" | 2
! colspan="8" | 3
|-
! style="border-top: none" | [[Octet (computing)|Octet]]
! [[Bit]]
! style="width:2.6%;"| 0
! style="width:2.6%;"| 1
! style="width:2.6%;"| 2
! style="width:2.6%;"| 3
! style="width:2.6%;"| 4
! style="width:2.6%;"| 5
! style="width:2.6%;"| 6
! style="width:2.6%;"| 7
! style="width:2.6%;"| 8
! style="width:2.6%;"| 9
! style="width:2.6%;"| 10
! style="width:2.6%;"| 11
! style="width:2.6%;"| 12
! style="width:2.6%;"| 13
! style="width:2.6%;"| 14
! style="width:2.6%;"| 15
! style="width:2.6%;"| 16
! style="width:2.6%;"| 17
! style="width:2.6%;"| 18
! style="width:2.6%;"| 19
! style="width:2.6%;"| 20
! style="width:2.6%;"| 21
! style="width:2.6%;"| 22
! style="width:2.6%;"| 23
! style="width:2.6%;"| 24
! style="width:2.6%;"| 25
! style="width:2.6%;"| 26
! style="width:2.6%;"| 27
! style="width:2.6%;"| 28
! style="width:2.6%;"| 29
! style="width:2.6%;"| 30
! style="width:2.6%;"| 31
|-
! 0
! 0
| colspan="32" style="background:#ffd0d0;"|Source IPv4 Address
|-
! 4
! 32
| colspan="32" style="background:#ffd0d0;"|Destination IPv4 Address
|-
! 8
! 64
| colspan="8" style="background:#ffd0d0;"|Zeroes
| colspan="8" style="background:#ffd0d0;"|Protocol
| colspan="16" style="background:#ffd0d0;"|UDP Length
|-
! 12
! 96
| colspan="16"|Source Port
| colspan="16"|Destination Port
|-
! 16
! 128
| colspan="16"|Length
| colspan="16"|Checksum
|-
! 20
! 160+
| colspan="32"|Data
|}

← Older revision		Revision as of 23:12, 21 September 2017
Line 1:		Line 1:
		+	= troubleshooting =
		+
		+	The P25nx network sends to multicast and there can only be one multicast talker at a time.
		+
		+	From time to time it will loop, generally due to misconfiguration on a given client. This will present double the packets on the receiving multicast interface and generally cause the ducks screwing noise.
		+
		+	To deal with this, you must find the user doing the looping and null route them.
		+
		+	To find if this is an issue use the following command:
		+
		+	'''sh ip mfib active 2'''
		+	Active Multicast Sources - sending >= 2 kbps
		+	Default
		+	Group: '''239.1.0.1''' '''<< This is the World Wide Group 10100 multicast IP'''
		+	Source: '''172.31.4.102''', '''<< the known node'''
		+	SW Rate: 48 pps/20 kbps(1sec), 2 kbps(last 581 sec)
		+	Source: ''172.31.4.110''', '''<< the looper'''
		+	SW Rate: 45 pps/19 kbps(1sec), 4 kbps(last 1219 sec)
		+
		+	Normally if things are working you may see senders cached, if there is a fast back and forth. However in a quiet network, you should only see one sender on a given multicast destination IP. Wait until there is no activity and then key your known node. In the above case, the known node is 172.31.4.110.
		+
		+	Verify this a few times, and then ensure that is truly one node.
		+
		+	As we have DMVPN running, this route will be to a private IP on Tunnel0, use the Show IP route command
		+
		+	sh ip route 172.31.4.110
		+	Routing entry for 172.31.4.108/30
		+	Known via "ospf 1", distance 110, metric 101, type intra area
		+	Last update from '''172.21.4.76''' on Tunnel0, 19:25:20 ago
		+	Routing Descriptor Blocks:
		+	* 172.21.4.76, from '''10.2.4.76''', 19:25:20 ago, via Tunnel0
		+	Route metric is 101, traffic share count is 1
		+
		+	172.21.4.76 is the senders interface on Tunnel0
		+	10.2.4.76 is the sender's router loopback
		+
		+	To map this to the public IP use "sh ip nhrp
		+
		+	sh ip nhrp 172.21.4.76
		+	172.21.4.76/32 via 172.21.4.76
		+	Tunnel0 created 19:50:05, expire 00:09:49
		+	Type: dynamic, Flags: unique registered used
		+	NBMA address: '''104.187.150.145'''
		+	(Claimed NBMA address: 192.168.2.4)
		+
		+	104.187.150.145 is the users public IP, and you can see they are behind NAT as the users router is claiming it's public IP is 192.168.2.4
		+
		+	Null routing that public IP will block them from the network
		+	ip route 104.187.150.145 255.255.255.255 Null0
		+
		+	However this will not allow access into that router, and you can keep the router access open by just null routing the IP of the sender
		+
		+	ip route 172.31.4.110 255.255.255.255 null0
		+
		+
		+
		+
		+
		+
		+
	There are three formats for the p25 network packet. All ride inside of a [https://en.wikipedia.org/wiki/User_Datagram_Protocol UDP] packet		There are three formats for the p25 network packet. All ride inside of a [https://en.wikipedia.org/wiki/User_Datagram_Protocol UDP] packet
		+

P25nx - Revision history

Bryan: Added info about looping

Bryan: P25 Network Exchange packet format