1)
 when qpidd started with "--cluster-url=amqp::22". qpid-cluster shows following:
 # qpid-cluster
       Members: ID=10.43.54.1:24749 URL=amqp:tcp:127.0.0.1:22


From AMQP 0-10 documentation:
Domain: connection.amqp-host-url
amqp_url = "amqp:" prot_addr_list
prot_addr_list = [prot_addr ","]* prot_addr
prot_addr = tcp_prot_addr | tls_prot_addr
tcp_prot_addr = tcp_id tcp_addr
tcp_id = "tcp:" | ""
tcp_addr = [host [":" port] ]
host = <as per http://www.ietf.org/rfc/rfc3986.txt>
port = number


to see it working that way, AMQP should read something similar to tcp_addr = [host [":" port] ] | [":port"] | ""
am i right?


2)
having in mind chapter 6.2.3 of http://www.ietf.org/rfc/rfc3986.txt, i'm not able to find in AMQP specification what should happend if host is unspecified, especially that host part of URI should be filled with localhost address.

I believe the fix to require the hostname is simple:

Index: src/qpid/Url.cpp
===================================================================
--- src/qpid/Url.cpp	(revision 933532)
+++ src/qpid/Url.cpp	(working copy)
@@ -116,7 +116,7 @@
         const char* start=i;
         while (unreserved() || pctEncoded())
             ;
-        if (start == i) h = LOCALHOST; // Default
+        if (start == i) return false;//host is required
         else h.assign(start, i);
         return true;
     }

So unless the above is intended, I suggest we commit that and close the issue.

Fixed in r933970. The host is now required.

when cluster-url will be set to "amqp:" or "amqp:tcp:" without host and/or port will it proceed?

If the cluster-url is not valid qpidd won't start, so host must be included (port neede not be).

ok i've generated over 131072 URL's, and checked with 
echo "${cluster_urls}" | grep -Poe '^((amqp:)*(tcp:)*)*([\d|\w|\-\.]+)(:([1-5]*[0-9]{0,4}|((6553[0-6])|(655[0-2][0-9])|(65[0-4][0-9][0-9])|(6[0-4][0-9]{3}))))*$' | grep -v -Poe '(^:+)|((:+$)|(:0+$))'

current rule for cluster-url seems to be: [[amqp:]tcp:]hostname[:port]

if only hostname is set or any other subset, cluster url is supplemented with defaults so for cluster-url=my-host-name its transformed into form of amqp:tcp:my-host-name:5672

so i guess we need to change documentation for MRG or AMQP.

--> VERIFIED

    Technical note added. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    New Contents:
Cause:
    The current AMQP spec says, for connection.amqp-host-url
        tcp_addr = [host [":" port] ]

  Consequence:
    This allows nonsense cluster URLs such as:
        amqp:/amqp:tcp:
    which are confusing to customers.

  
  Fix:
    require a hostname


  Result:
    current cluster URL rule is now:
      [[amqp:]tcp:]hostname[:port]
    which generates more reasonable URLs.

    Technical note updated. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    Diffed Contents:
@@ -1,18 +1,9 @@
-Cause:
-    The current AMQP spec says, for connection.amqp-host-url
-        tcp_addr = [host [":" port] ]
+The current Advanced Message Queuing Protocol (AMQP) specification allows a cluster URL in the following form:
 
-  Consequence:
-    This allows nonsense cluster URLs such as:
-        amqp:/amqp:tcp:
-    which are confusing to customers.
+  [host [":" port] ]
 
-  
-  Fix:
-    require a hostname
+However, this also allows URLs such as "amqp:/amqp:tcp:", which can be confusing. With this update, a hostname is required, so that the valid cluster URL now looks as follows:
 
-
+  [[amqp:]tcp:]hostname[:port]
-  Result:
+  
-    current cluster URL rule is now:
+This change ensures that all URLs now take the reasonable form.-      [[amqp:]tcp:]hostname[:port]
-    which generates more reasonable URLs.

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2010-0773.html